geotechnical laboratory manual-ii - copy

Geotechnical and Foundation engineering Lab Manual

Geotechnical laboratory manual Page i

Geotechnical and Foundation

Engineering

Lab Manual

Produced by;

Engr.Saeedullah Jan Civil Engineering Department

BUITEMS, Quetta


Balochistan University of of Information Technology Engineering & Management Sciences i (BUITEMS), Quetta

Practical Workbook

Geotechnical and Foundation Engineering

This is to certify that this practical workbook

contains 124 pages.

Chairman September 2012

Department of Civil Engineering Balochistan University of Information Technology

Engineering & Management Sciences, Quetta


Balochistan University of of Information Technology Engineering & Management Sciences ii (BUITEMS), Quetta

THE IMPORTANCE OF GEOTECHNICAL LABORATORY TESTING Soil can exist as a naturally occurring material in its undisturbed state, or as a compacted material. Geotechnical engineering involves the understanding and prediction of the behavior of soil. Like other construction materials, soil possesses mechanical properties related to strength, compressibility, and permeability. It is important to quantify these properties to predict how soil will behave under field loading for the safe design of soil structures (e.g. embankments, dams, waste containment liners, highway base courses, etc.), as well as other structures that will overly the soil. Quantification of the mechanical properties of soil is performed in the laboratory using standardized laboratory tests.

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EE NN GG II NN EE EE RR II NN GG && MM AA NN AA GG EE MM EE NN TT SS CC II EE NN CC EE SS ,, QQ UU EE TT TT AA


Balochistan University of of Information Technology Engineering & Management Sciences iii (BUITEMS), Quetta

CC OO NN TT EE NN TT SS

1 IN PLACE SOIL DENSITY USING SAND CONE METHOD 1

2 COEFFICIENT OF PERMEABILITY (CONSTANT HEAD METHOD) 11

3 COEFFICIENT OF PERMEABILITY (FALLING HEAD METHOD) 21

4 DIRECT SHEAR TEST 30

5 ONE DIMENSIONAL CONSOLIDATION TEST 42

6 STANDARD PENETRATION TEST 63

7 UNCONFINED COMPRESSION TEST 73

8 TRIAXIAL TEST 82

9 PLATE LOAD TEST 96

10 CALIFORNIA BEARING RATIO TEST 106

BIBLIOGRAPHY 118

In situ Density By sand Cone Method

Balochistan University of of Information Technology Engineering & Management Sciences 1 (BUITEMS), Quetta

1 IN PLACE SOIL

DENSITY USING

SAND CONE

METHOD



11 .. 11 II NN TT RR OO DD UU CC TT II OO NN

Basically, both the sand-cone and balloon-density methods use the same principle. That

is, one obtained a known weight of damp (or wet) soil from a small excavation of

somewhat irregular shape (a hole) in the ground. If one knows the volume of the hole, the

wet density is simply computed as

holeofvolume

soildampofweightwet

and if one obtained the water content w of the excavated material, the dry unit weight of

the material is

w1

wetdry

The sand cone method is an indirect means of obtaining the volume of the hole. The sand

used (often Ottawa sand) is generally material passing the No. 20 sieve but retained on

the No. 30 sieve. If one has a constant-density material of, say, 1.60 g/cm³ and pouring

4800 g of this material into an irregular-shaped hole, the volume of the hole can be found

by proportion as:

3

3

cm/g60.1

cm1

4800

V

material unit wt.of

hole fill toused material of wt.Vhole

11..11..11 DDEEFFIINNIITTIIOONNSS

BBUULLKK DDEENNSSIITTYY

Bulk density refers to the weight (mass) of soil per unit volume and the soils bulk density

is normally expressed in g cm-3

(weight divided by volume).

UUNNIITT WWEEIIGGHHTT

Unit weight is defined as weight per unit volume.

11 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT

The object of this test is to determine the dry density of natural or compacted soil, in-

place and its degree of compaction.

11 .. 33 SS CC OO PP EE OO FF TT EE SS TT

Once compaction criteria are established for the soil to be used at a particular site,

generally with both moisture and density limitations, some means of verification of the

results must be used. On all small projects and nearly all-large projects, this verification is



achieved by either the sand-cone method or the balloon density method. On a few large,

nuclear devices have been and are considered further.

11 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE SS

ASTM: D 1556-64

AASHTO: T 191-61

11 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT

The test equipment consists of:

1. Sand cone apparatus

2. Shovels (Digging tools)

3. Metal tray with a central circular hole of diameter equal to the diameter of the

pouring cone

4. Balance accurate to 1g

5. clean, uniformly graded sand ranging from #20 to #30 sieve such as Ottawa Sand

6. Paint brush to collect soil from template

7. Hammer and three nails to fix the metal tray on the spot

8. Spoon

9. plastic air tight bag for carrying wet excavated soil from field to laboratory

10. Oven with temperature kept at about 105-110oC

Figure 1.1 Sand-Cone Apparatus



Figure 1.2 Ottawa sand

11 .. 66 PP RR EE PP AA RR AA TT II OO NN OO FF SS AA MM PP LL EE AA NN DD TT EE SS TT

SS PP EE CC II MM EE NN

Carefully collect a sample from undisturbed core of soil adjacent to the points of soil

moisture determination using the tins provided. Trim off excess soil and wrap core in

labeled polythene bag for transport to laboratory.

11 .. 77 AA DD JJ UU SS TT MM EE NN TT AA NN DD CC AA LL II BB RR AA TT II OO NN OO FF

II NN SS TT RR UU MM EE NN TT

Prior to determining the bulk density of the sand and prior to conducting density tests, the

technician is required to determine the weight of sand needed to fill the large cone of the

density apparatus and the accompanying base plate. This weight is determined to the

nearest 0.01 kilogram and is referred to as the Cone Correction. The density apparatus

and the base plate are required to remain together and not be interchanged with other

devices without recalculating the Cone Correction.

The procedure for determination of the Cone Correction is detailed in AASHTO T 191

and is summarized as follows:

1. Fill the apparatus with the calibration sand and record the weight to the nearest

0.01 lb

2. Place the base plate on a clean, level surface

3. Invert the apparatus onto the base plate and open the valve to allow the cone and

the base plate to fill with sand

4. When the sand stops flowing into the cone, shut the valve and weigh the apparatus

to the nearest 0.01 lb

5. The difference between the full weight of the apparatus and the final weight after

filling the cone is referred to as the Cone Correction.



11 .. 88 TT EE SS TT PP RR OO CC EE DD UU RR EE

11..88..11 DDEETTEERRMMIINNAATTIIOONN OOFF MMAASSSS OOFF SSAANNDD FFIILLLLIINNGG TTHHEE CCOONNEE

1. Fill the clean closely graded sand in the sand-pouring cylinder up to a height of

1cm below the top. Determine the total mass/weight of Bottle + Cone +Sand (M1).

2. Open the valve and allow the sand to flow out. Close the valve when no further

movement of sand is observed. Lift the jar carefully. Weigh the sand collected on

the glass surface. Its mass (Mc) is the mass of sand filling the pouring cone. Or

remove the bottle and cone combination from the base plate, and determine its

mass (M2), thus the mass of sand to fill the cone can be determined as:

Mc = M1 –M2

Pour the sand back into the cylinder, to have the same constant mass.

11..88..22 DDEETTEERRMMIINNAATTIIOONN OOFF BBUULLKK DDEENNSSIITTYY OOFF SSAANNDD

1. Determine the volume of the calibrating container. It would be either mentioned

or can be by measuring the diameter or by filling it with water full to the top and

finding the mass of water, it is therefore

m V

For pure water normally the mass density can be taken as = 1g/cm3

2. Place the sand-pouring cylinder concentrically on the top of the calibrating

container. Open the shutter and permit the sand to run into the container. When

there is no further movement of sand, close the shutter. Remove the cylinder and

find its mass. Thus mass per unit volume will give the bulk density of the sand.

On other hand this can also be done by taking a proctor compaction mold and,

using a spoon, filling it with Ottawa sand. Avoid any vibration of other means of

compaction of the sand poured into the mould. When the mold is full, strike off

the top of the mould with the steel straight edge, determine the mass of the sand in

the mold. The bulk density of the Ottawa sand can be then be given as:

V

Md

Where

M = Mass of the sand filling the mould.

V = Volume of the mould (1/30 ft3)

d = Bulk density of the sand.

11..88..33 DDEETTEERRMMIINNAATTIIOONN OOFF DDRRYY DDEENNSSIITTYY OOFF SSOOIILL IINN--PPLLAACCEE

1. Expose about 45cm2 area of the soil to be tested and trim it down to level surface.

Keep the tray on the level surface and fix it by the help of nails in its position and

excavate a circular hole of approximately 10cm in diameter and 15 cm deep and

collect all the excavated soil in the tray. Find the mass of the excavated soil.

2. Remove the tray, and place the sand-pouring cylinder concentrically on the hole.

Open the shutter and permit the sand to run into the hole. Close the shutter when



no further movement of the sand is seen. Remove the cylinder and determine it’s

mass.

3. Keep a representative sample of the excavated soil for water content

determination.

11 .. 99 CC AA LL CC UU LL AA TT II OO NN SS

Unit weight of soil g

Dry density

1d

11 .. 11 00 RR EE SS UU LL TT SS

The dry unit weight of the soil = _________g/cm3

Dry unit weight/ specific weight

1d

11 .. 11 11 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS

This test is applied in the cases like embankment and pavement construction; and is

basically a quality control test where certain degree of compaction is required. This test

is also used in stability analysis of embankments and slopes, for the calculation of

pressure in underlying strata for settlement problems and also designs of underground

structures.

11 .. 11 22 PP RR EE CC AA UU TT II OO NN SS

1. The excavation during sand cone method should be as rapid as possible to

maintain the representative moisture content.

2. The field test holes may be quite small, thus the error multiple is largest is

absolutely essential that no soil be lost during excavation

3. The largest possible water content sample should be used to improve test

reliability.

4. When using the sand cone method avoid vibrating either the ground in the area or

the sand jug as this will introduce too much sand into the hole thus causing an

apparent increase in the hole’s volume.



11 .. 11 33 SS AA MM PP LL EE PP RR OO BB LL EE MM

SOIL TESTING LABORATORY

FIELD UNIT WEIGHT-SAND CONE METHOD

Sample No. 15 Project No. SR 2828

Boring No. B-21 Location Newell, N.C

Depth of sample 3 ft

Description of Sample Reddish brown silty clay

Tested by John Doe Date 1/26/89

(A) Determination of mass of sand filling the cone

The total mass of Bottle + Cone +Sand before filling the cone (M1) 9098gm

The total mass of Bottle + Cone +Sand after filling the cone (M2) 7268gm

Mass of the sand filling the cone (Mc) = M1- M2 1830gm

(B) Determination of bulk density of sand

The volume of the calibrating container (V) 2305cm3

The mass of the sand in the mold/calibrating container (M3) 3400gm

The bulk density of the Ottawa sand V

M 3s 1.47 gm/cm

3

(C) Determination of dry density of soil in- place

The mass of the excavated wet soil M4 2658gm

The total mass of Bottle + Cone +Sand before filling the hole (M5) 9066gm

The total mass of Bottle + Cone +Sand after filling the hole (M6) 4980gm

Mass of the sand filling the hole (Mh) = M5- M6 – Mc 2256gm

Volume of hole

s

hh

MV

1535cm

3

Bulk density of soil sh

4

h

4

M

M or

V

M 1.73 gm/cm

3

Unit weight of soil g 16097 kg/cm3



(D) Water content determination

Mass of can + wet soil M7 106.41 gm

Mass of can + dry soil M8 103.38 gm

Mass water Mw = M7 – M8 3.03 gm

Mass of can M9 15.35 gm

Mass of dry soil Md = M8 – M9 88.03 gm

Water content

dM

Mw 3044%

Dry density

1d


1d 1.672 gm/cm

3

Result

The dry unit weight of the soil = ______1.672___ gm/cm3




FIELD UNIT WEIGHT-SAND CONE METHOD

Sample No. Project No.

Boring No. Location

Depth of sample

Description of Sample

Tested by Date

(A) Determination of mass of sand filling the cone

The total mass of Bottle + Cone +Sand before filling the cone (M1)

The total mass of Bottle + Cone +Sand after filling the cone (M2)

Mass of the sand filling the cone (Mc) = M1- M2

(B) Determination of bulk density of sand

The volume of the calibrating container (V)

The mass of the sand in the mold/calibrating container (M3)

The bulk density of the Ottawa sand V

M 3s

(C) Determination of dry density of soil in- place

The mass of the excavated wet soil M4

The total mass of Bottle + Cone +Sand before filling the hole (M5)

The total mass of Bottle + Cone +Sand after filling the hole (M6)

Mass of the sand filling the hole (Mh) = M5- M6 – Mc

Volume of hole

s

hh

MV

Bulk density of soil sh

4

h

4

M

M or

V

M

Unit weight of soil g



(D) Water content determination

Mass of can + wet soil M7

Mass of can + dry soil M8

Mass water Mw = M7 – M8

Mass of can M9

Mass of dry soil Md = M8 – M9

Water content

dM

Mw

Dry density

1d


1d

Result

The dry unit weight of the soil = gm/cm3

Coefficient Of Permeability by Constant Head Method


2

COEFFICIENT

OF

PERMEABILITY (Constant Head Method)




In geotechnical engineering problems measuring the flow of water through the soil is a

very important consideration. Soil has pores due to inter-particle spaces (voids). The

interconnectivity of voids determines the permeability characteristics of soil. Thus, rock,

concrete, and other porous material may also be permeable (pervious). Materials such as

clays and silts in natural deposits have considerable porosity but are practically

impervious or have permeability significantly low (in comparison to sand or gravel).

The coefficient of permeability of soil is important in various aspects such as:

Determining the seepage through or beneath dams and levees and into water wells; in

stability analyses of hydraulic structures through evaluation of uplift or seepage forces;

and in regulating seepage control and design of seepage velocities to check erosion in

earthen structures

The other important applications are in estimation of ground water flow, percolation,

surface recharge and yield from wells.


PPEERRMMEEAABBIILLIITTYY

Permeability is the ease with which the water flows through a soil medium.

CCOOEEFFFFIICCIIEENNTT OOFF PPEERRMMEEAABBIILLIITTYY

The rate of flow under laminar flow conditions through a unit cross sectional are of

porous medium under unit hydraulic gradient is defined as coefficient of permeability.

22 .. 22 OO BB JJ EE CC TT II VV EE SS

To introduce a method of determining coefficient of permeability of a coarse-grained soil

by constant head method.

22 .. 33 SS CC OO PP EE

The test method measures the flow rate of water through a soil specimen of a known

gross cross-sectional area, applying constant head and using Darcy’s expression for

determining its permeability constant.

22 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE

ASTM D234-68

AASHTO T215-66



22 .. 55 AA PP PP AA RR AA TT UU SS

1. Permeability device (Permeameter)

2. Constant head tank

3. Thermometer, range 0 to 50oC, accurate to 0.1

oC

4. Stop watch.

5. Graduated cylinder.

6. De-aired distilled water

7. Coarse-grained soils


1. Measure the initial mass of the pan along with the dry soil (M1).

2. Remove the cap and upper chamber of the Permeameter by unscrewing the

knurled cap nuts and lifting them off the tie rods.

3. Measure the inside diameter of upper and lower chambers. Calculate the average

inside diameter of the Permeameter (D).

4. Place one porous stone on the inner support ring in the base of the chamber then

place a filter paper on top of the porous stone.

5. Mix the soil with a sufficient quantity of distilled water to prevent the segregation

of particle sizes during placement into the Permeameter.

6. Enough water should be added so that the mixture may flow freely.

7. Using a scoop, pour the prepared soil into the lower chamber using a circular

motion to fill it to a depth of 1.5 cm. A uniform layer should be formed.

8. Use the tamping device to compact the layer of soil. Use approximately ten rams

of the tamper per layer and provide uniform coverage of the soil surface. Repeat

the compaction procedure until the soil is within 2 cm. of the top of the lower

chamber section.

9. Replace the upper chamber section, and don’t forget the rubber

Figure 2.1 constant head assembly



10. Gasket that goes between the chamber sections. Be careful not to disturb the soil

that has already been compacted. Continue the placement operation until the level

of the soil is about 2 cm. below the rim of the upper chamber.

11. Level the top surface of the soil and place a filter paper and then the porous stone

on it.

12. Place the compression spring on the porous stone and replace the chamber cap and

its sealing gasket. Secure the cap firmly with the cap nuts.

13. Measure the sample length at four locations around the circumference of the

Permeameter and compute the average length. Record it as the sample length.

14. Keep the pan with remaining soil in the drying oven.

15. Adjust the level of the funnel to allow the constant water level in it to remain a

few inches above the top of the soil.

16. Connect the flexible tube from the tail of the funnel to the bottom outlet of the

Permeameter and keep the valves on the top of the Permeameter open.

17. Place tubing from the top outlet to the sink to collect any water that may come

out. Open the bottom valve and allow the water to flow into the Permeameter.

18. As soon as the water begins to flow out of the top control (de-airing) valve, close

the control valve, letting water flow out of the outlet for some time.

19. Close the bottom outlet valve and disconnect the tubing at the bottom.

20. Connect the funnel tubing to the top side port. Open the bottom outlet valve and

raise the funnel to a convenient height to get a reasonable steady flow of water.

21. Allow adequate time for the flow pattern to stabilize.

22. Measure the time it takes to fill a volume of 750 - 1000 ml using the graduated

cylinder, and then measure the temperature of the water.

23. Repeat this process three times and compute the average time, average volume,

and average temperature. Record the values as t, Q, and T, respectively.

Figure 2.2 Half assembled permeameter.



24. Measure the vertical distance between the funnel head level and the chamber

outflow level, and record the distance as h.

25. Repeat step 17 and 18 with different vertical distances.

26. Remove the pan from the drying oven and measure the final mass of the pan along

with the dry soil (M2).


Using Bowles apparatus for determination permeability coefficient by measuring flow

through soil under a constant head is calculated from the following equation

ChtA

QLk

Where;

Q = quantity of flow, cm3 or ml

L = length of the sample, cm

h = applied head (constant) cm

t = time interval seconds

A = cross-sectional area of the sample cm2

C = Temperature correction for viscosity of water at 20C

Result

The coefficient of permeability of the given coarse-grained soil by Constant Head

Permeability test is found to be, k =___________________cm/s.

Soil Coefficient. of Perm., k,

cm/sec Degree of Permeability

Gravel >10-1 Very high

Sandy gravel, clean sand, fine

sand

10-1 > k > 10-3 High to Medium

Sand, dirty sand, silty sand 10-3 > k > 10-5 Low

Silt, silty clay 10-5 > k > 10-7 Very low

Clay <10-7 Virtually impermeable

Table 2.1 soil permeability properties

22 .. 88 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS

The important applications of permeability are in estimation of ground water flow,

percolation, surface recharge and yield from wells

In the design of geotechnical engineering projects, one of the most important soil

properties of interest to the soils engineer is permeability. To some degree, permeability

will play a role in the design of almost any structure. For example, the durability of

concrete is related to its permeability. In designs that make use of earthen materials (soils

and rock, etc.)The permeability of these materials will usually be of great importance.

To illustrate the importance of permeability in geotechnical design, consider the

following applications where knowledge of permeability is required.

Permeability influences the rate of settlement of a saturated soil under load.



The rate of flow to wells from an aquifer is dependent on permeability.

The design of earth dams is very much based upon the permeability of the soils used.

The performance of landfill liners is based upon their permeability.

The stability of slopes and retaining structures can be greatly affected by the permeability

of the soils involved.

Filters to prevent piping and erosion are designed based upon their permeability.

Soils are permeable (water may flow through them) because they consist not only of

solid, but a network of interconnected pores. The degree to which soils are permeable

depends upon a number of factors, such as soil type, grain size distribution and soil

history. This degree of permeability is characterized by the coefficient of permeability.

22 .. 99 PP RR EE CC AA UU TT II OO NN SS

1. The head may be varying.

2. The temperature should be constant

3. Be careful not to jar or bump the apparatus at all.





CONSTANT HEAD PERMEABILITY TEST

Description of soil Brown, medium coarse sand

Sample No. 2 Location soil laboratory

Unit Weight Determination

length between manometer outlets, L (cm) 11.43

Diameter of soil specimen, D (cm) 10.16

Cross sectional area of soil specimen A (cm2) (i.e. D

2/4) 81.0837088

Height H1 ,(cm) 20

Height H2 ,(cm) 4.5

Height of specimen (cm) (H1-H2) 15.5

Volume of specimen (cm3) 1256.797486

weight of air dried soil before compaction, W1 (g) 3200

Weight of unused remaining portion of soil after compaction, W2 (g) 1102.5

Weight of soil specimen (air dried) (g) 2097.5

Unit weight of soil specimen (air dried ) (lb/ft3) 104.140883

Water Content of Soil Specimen (air dried) (%) 1.100079428

can no. 2-A

weight of air dried soil + can 308.17

weight of oven dried soil + can 305.4

weight of can 53.6

water content of air dried soil (%) 1.100079428

Dry unit weight of soil specimen (lb/ft3) 103.0077163

specific gravity of soil 2.71

Volume of solids (ft3) 0.60913826

Volume of voids (ft3) 0.39086174

Void ratio e, of soil specimen 0.641663421

Permeability Test

length between manometer outlets, L (cm) 11.43

Cross sectional area of soil specimen A (cm2) 81.0837088



Result

The coefficient of permeability of the given coarse-grained soil by Constant Head Permeability test is found to be,

k =_0.0918__cm/s.

Test

No.

Average

flow,

Q

(cm3)

Time of

collection

t

(sec)

Temperatu

re of water,

T

(oC)

Manometer Readings Head

difference,

h

(cm)

ChtA

QLk

(cm/sec)

Ratio of viscosity at

ToC/Viscosity at

20oC

Permeability at

20oC,

k20

(cm/s)

h1

(cm)

h2

(cm)

1 250 65 23 10.9 5.4 5.5 0.0986 0.9311 0.091785

2 250 63 24 10.9 5.4 5.5 0.1017 0.9097 0.092523

3 250 64 24 10.9 5.4 5.5 0.1001 0.9097 0.091077

4




CONSTANT HEAD PERMEABILITY TEST

Description of soil

Sample No. Location


length between manometer outlets, L (cm)

Diameter of soil specimen, D (cm)

Cross sectional area of soil specimen A (cm2) (i.e. D

2/4)

Height H1 ,(cm)

Height H2 ,(cm)

Height of specimen (cm) (H1-H2)

Volume of specimen (cm3)

weight of air dried soil before compaction, W1 (g)

Weight of unused remaining portion of soil after compaction, W2 (g)

Weight of soil specimen (air dried) (g)

Unit weight of soil specimen (air dried ) (lb/ft3)

Water Content of Soil Specimen (air dried) (%)

can no.

weight of air dried soil + can

weight of oven dried soil + can

weight of can

Water content of air dried soil (%)

Dry unit weight of soil specimen (lb/ft3)

specific gravity of soil

Volume of solids (ft3)

Volume of voids (ft3)

Void ratio e, of soil specimen

Permeability Test

length between manometer outlets, L (cm)

Cross sectional area of soil specimen A (cm2)



Result

The coefficient of permeability of the given coarse-grained soil by Constant Head Permeability test is found to be, k

=___________________cm/s.

Test

No.

Average

flow,

Q

(cm3)

Time of

collection

t

(sec)

Temperatur

e of water,

T

(oC)

Manometer Readings Head

difference,

h

(cm)

ChtA

QLk

(cm/sec)

Ratio of viscosity at

ToC/Viscosity at 20

oC

Permeabili

ty at 20oC,

k20

(cm/s) h1

(cm)

h2

(cm)

1

2

3

4

Coefficient Of Permeability by Falling Head Method


3

COEFFICIENT

OF

PERMEABILITY (Falling Head Method)




Fine soils such as silt and clay have considerable low permeability, which makes

determination of their permeability constant practically impossible when using constant

head test. Hence alternate method is suggested which measures the flow of water through

soil sample by applying variable head that decreases with time as the level of water above

the soil samples decreases (falling head). The drop in the level is of water in a known

time is measured for calculating the coefficient of permeability.


PPEERRMMEEAABBIILLIITTYY

Permeability is the ease with which the water flows through a soil medium.

33 .. 22 OO BB JJ EE CC TT II VV EE SS

To determine the coefficient of permeability of a fine grained soil by falling head method

such as fine sand, silt, or clay. This test may also be used for coarse grained soils.

33 .. 33 SS CC OO PP EE

The test method is applicable to fine-grained soils through which rate of flow of water is

measured keeping known gross cross-sectional area constant while the applied head

(hydraulic potential) decreases gradually with time. This test determines the permeability

of sample that has permeability less than about 10-3

cm/s (less permeable soil).


ASTM D234-68

AASHTO T215-66

33 .. 55 AA PP PP AA RR AA TT UU SS

1. Falling Head Permeability device (Permeameter).

2. Thermometer.

3. Stop watch.

4. Graduated cylinder.

5. Fine grained material

6. Ring stand with test-tube clamp or other means to develop a differential head

across soil sample.

7. Burette with stand.

8. Electronic balance (LC = 0.1g)



33 .. 66 PP RR OO CC EE DD UU RR EE

1. Weigh the Permeameter mold with the base plate and porous stone attached. Also

measure the inside mold diameter and height in order to calculate the cross-

sectional area and sample length, as well as the cross-sectional area of the burette,

which can be determined from the distance between graduations.

2. Fill the mold with the soil sample by a method appropriate to the material and

purpose of testing.

3. For tests on loose cohesion less soils: Assemble the Permeameter base and mold,

then using a large funnel let the dry cohesion less soil rain into the mold at a

constant rate. The funnel should be kept about one inch above the soil surface and

continuously moved in a spiral motion allowing the sand to accumulate uniformly.

An oven-dry moisture determination (AASHTO T 265) shall be made in order to

compute the dry density of the soil.

4. For tests on compacted soils: Using the Permeameter molds, embankment type

materials are compacted in accordance with AASHTO T-99, Method C, while

base and stabilized sub grade type materials are compacted in accordance with

AASHTO T 180. After compaction, the mold is removed from the compaction

base and assembled in the Permeameter base.

5. Weigh the assembled mold and base plate with soil and determine the density of

dry soil. Measure the length of the soil sample L. If material is loose, the length of

the soil sample should be measured before and after the permeability tests to

determine any change in length due to consolidation of soil. The final value of L is

used for computations of K.

6. Place a piece of filter paper on top and bottom of the sample, then place the

perforated disc. Making sure the rim is clean, place the gasket and seat the cover.

7. Using a vacuum pump or suitable aspirator, (Fig. 1) evacuate the specimen a

minimum of 15 minutes to remove air adhering to soil particles and from the voids

(Note 1). Follow the evacuation by a slow saturation of the specimen from the

Figure 3.1 Assembled falling head apparatus



bottom upward, under vacuum, in order to free any remaining air in the specimen.

De-aired water is recommended for the saturation of the specimen. The water

supply should be slightly elevated in order to produce a small hydraulic head

during saturation.

8. Note 1: A maximum vacuum of 250 mm (10 in.) mercury is recommended. Some

sandy soils with permeability greater than 10-³ should not be subjected to a

vacuum greater than 125 mm (5 in.) mercury. In no case shall a combination of

vacuum and hydraulic head be great enough to produce turbulent flow in the

specimen during saturation.

9. After the specimen has been saturated and the Permeameter is full of water,

partially close the valve on the outlet tube to produce a minimum steady state flow

at the inlet, and then disconnect the vacuum.

10. Immediately attach the Permeameter to the rubber tube at the base of the burette.

The burette and the rubber tube should already be filled and flowing with water

from a supply, which has been temperature stabilized and de aired. The

Permeameter should now be free of air bubbles.

11. Close the outlet valve and fill the burette to a convenient height.

12. Remember that the inlet valve is partially open and should be completely opened

at this point. Measure the hydraulic head across the sample to obtain ho.

13. Disconnect the outlet tube from the saturation reservoir and place it in a filled

container.

14. Open the outlet valve and simultaneously start timing the test. Allow water to flow

through the sample until the burette is almost empty.

15. Simultaneously record the elapsed time and clamp only the outlet tube. Measure

the hydraulic head across the sample at this time to obtain h1. Take the

temperature of the test.

16. Refill the burette and repeat step Section 4.9 two additional times.

17. Take the temperature each time.

18. Compute the coefficients of permeability at the test temperature, kt, for each trial,

and k at 20°C using the correction values from table 1.

19. Average all three or the two closest values for k = 20.


The coefficient of permeability is calculated from the following equation,

Ch

h

At

aLk

2

1ln

Where,

a = cross-sectional area of burette cm2

L = length of the sample cm

h1 = Initial hydraulic head cm

h2 = Final hydraulic head cm

t = time interval seconds

A = cross-sectional area of the soil sample cm2

C = Temperature correction for viscosity of water at 20C.



33 .. 88 RR EE SS UU LL TT SS

The coefficient of permeability of the given fine-grained soil by Falling Head

Permeability test is found to be, k =___________________cm/s.


Practical uses of falling head permeability test are 1. Settlements in structures

2. Methods for lowering the ground water table during construction

3. Design grouting pressures and quantities for soil stabilization

4. Freeze Thaw movements in soils (Note that coefficient of permeability ( k) varies

with temperature

5. as the viscosity of the fluids changes with temperature)

6. Design of recharge pits





FALLING HEAD PERMEABILITY TEST

Description of soil Brown, medium coarse sand

Sample No. 2 Location Soil laboratory


Weight of Permeameter (mold) with the base plate and

gasket attached + soil (g) 3401.1

Weight of empty Permeameter (mold) with the base plate

and gasket attached (g) 1098.5

Weight of soil specimen (g) 2302.6

Diameter of soil specimen, D (i.e., inside dia of mold)(cm) 10.16

Cross sectional area of soil specimen(ie 3.142*D2/4) 81.0837088

Length of soil specimen in Permeameter, L (cm) 15.8

volume of soil specimen 1281.122599

Unit weight of soil specimen (air dried) 112.1533881

Water content of soil specimen (air dried) (%) 1.100079428

can no. 2-A

weight of air dried soil + can 308.17

weight of oven dried soil + can 305.4

weight of can 53.6

Water content of soil specimen (air dried) (%) 1.100079428

Dry unit weight of soil specimen (lb/ft3) 110.9330365

Specific gravity of soil 2.71

Volume of solids 0.656004805

Volume of voids 0.343995195

Void ratio, e, of soil specimen 0.524379078



Test

No.

h1

(cm)

h2

(cm)

Test

duration,

t

(sec)

Temperature

of water,

T

(oC)

permeability

at T (oC),

KT

(cm/s)

Ratio of

viscosity at

ToC/Viscosity

at 20oC

Permeability at

20oC,

k20

(cm/s)

1 150 20 32.3 22 0.022223465 0.9531 0.02118

2 150 20 32.6 22 0.022018955 0.9531 0.02099

3 150 20 31.7 22 0.022644099 0.9531 0.02158

Calculation


Ch

h

At

aLk

2

1ln

Result


Permeability test is found to be, k20 oC =________0.06375___________cm/s.




FALLING HEAD PERMEABILITY TEST

Description of soil

Sample No. Location


Weight of permeameter (mold) with the base plate and gasket attached + soil (g)

Weight of empty permeameter (mold) with the base plate and gasket attached (g)

Weight of soil specimen (g)

Diameter of soil specimen, D (ie inside dia. of mold)(cm)

Cross sectional area of soil specimen(ie 3.142*D2/4)

Length of soil specimen in permeameter, L (cm)

volume of soil specimen

Unit weight of soil specimen (air dried)

water content of soil specimen(air dried) (%)

can no.

weight of air dried soil + can

weight of oven dried soil + can

weight of can

water content of soil specimen(air dried) (%)

Dry unit weight of soil specimen (lb/ft3)

Specific gravity of soil

Volume of solids

Volume of voids

Void ratio, e, of soil specimen



Test

No.

h1

(cm)

h2

(cm)

Test

duration,

t

(sec)

Temperature

of water,

T

(oC)

permeability

at T (oC),

KT

(cm/s)

Ratio of

viscosity at

ToC/Viscosity

at 20oC

Permeability at

20oC,

k20

(cm/s)

1

2

3

4

Calculation


Ch

h

At

aLk

2

1ln

Result


Permeability test is found to be, k20 oC =________ __________cm/s.

Direct Shear Test


4 DIRECT SHEAR

TEST

Direct Shear Test



Shear strength may be estimated by measuring the resistance offered against sliding friction

at the interface of two surfaces or layers within granular materials. According to Mohr-

Coulomb theory a soil will fail at shear stress greater than or equal to

= c + tan

This can be represented graphically by developing failure envelope(s) named after Mohr and

Coulomb.

Where,

= shear stress

c = cohesion

= Angle of internal friction

= Normal or vertical stress

Chart 4.1 Normal Stresses vs. Shear Stress

Direct shear test used to be much popular in geotechnical investigations but now is not being

used extensively as more precise and reliable shear measurement techniques (Triaxial tests)

have been developed and introduced as standard methods. The other reasons for limited use

of direct shear test are:

1. The area of the sample changes as the test progresses, but may not be very significant

as most samples fail at low deformations.

Direct Shear Test


2. The actual failure surface is not plane, as is assumed or as was intended the way shear

box was designed, nor is the shearing stress uniformly distributed over the failure

surface, as is assumed when performing calculations.

3. The test uses a small sample that makes test susceptible to errors when preparing

specimen (i.e. difficult to obtain a representative sample).

4. The size of the sample precludes much investigation into pore water during the test

(drained and undrained conditions)

5. Values of the modulus of the elasticity and Poisson’s ratio cannot be determined.


RREELLAATTIIVVEE LLAATTEERRAALL DDIISSPPLLAACCEEMMEENNTT

Relative lateral displacement – the horizontal displacement of the top and bottom shear box

halves relative to each other.

FFAAIILLUURREE

The stress condition at failure for a test specimen. Failure corresponds to the maximum shear

stress attained or the shear stress at 15-20 percent relative lateral displacement. Depending on

soil behavior and field application, other suitable criteria may be defined.

SSHHEEAARR SSTTRREENNGGTTHH

Maximum shear stress that can be sustained by a material before rupture is called shear

strength. It is the ultimate strength of a material subjected to shear loading.

CCOOHHEESSIIOONN

It is the soils inter-particle attraction which ultimately provides resistance to sliding of

particles one over the other.


This experiment is used to determine the internal angle of friction for a fine, dry sand by

means of a shear box apparatus.


Direct shear test is used to predict the value of the angle of internal friction and cohesion of

the soil parameters quickly. The laboratory report covers the laboratory procedures for

determining these values for cohesion less soils.

Direct Shear Test



ASTM D3080-72


1. Direct shear box apparatus

2. Loading frame (motor attached).

3. Dial gauge.

4. Proving ring.

5. Tamper.

6. Straight edge.

7. Balance to weigh up to 200 mg.

8. Aluminum container.

9. Spatula.

Figure 4.1 Direct shear devices and shear box

Direct Shear Test


44 .. 66 PP RR EE PP AA RR AA TT II OO NN OO FF SS AA MM PP LL EE SS AA NN DD TT EE SS TT SS PP EE CC II MM EE NN

Test specimen can be prepared by mixing water in sand and carefully put it in mould in

layers with the help of wooden tamper.


1. Check the inner dimension of the soil container.

2. Put the parts of the soil container together.

3. Calculate the volume of the container. Weigh the container.

4. Place the soil in smooth layers (approximately 10 mm thick). If a dense sample is

desired tamp the soil.

5. Weigh the soil container, the difference of these two is the weight of the soil.

Calculate the density of the soil.

6. Make the surface of the soil plane.

7. Put the upper grating on stone and loading block on top of soil.

8. Measure the thickness of soil specimen.

9. Apply the desired normal load.

10. Remove the shear pin.

11. Attach the dial gauge which measures the change of volume.

12. Record the initial reading of the dial gauge and calibration values.

13. Before proceeding to test check all adjustments to see that there is no connection

between two parts except sand/soil.

14. Start the motor. Take the reading of the shear force and record the reading.

15. Take volume change readings till failure.

16. Add 5 kg normal stress 0.5 kg/cm2 and continue the experiment till failure

17. Record carefully all the readings. Set the dial gauges zero, before starting the

experiment

Direct Shear Test



1. Compute the shear stress as τ = Ph / A

2. Compute the normal stress as σn = Pv / A

3. Compute the horizontal displacement, δh, and the vertical displacement, δv, for each

observed value.

4. Plot shearing stress against horizontal displacement and obtain the maximum value of

shearing stress, τmax.

5. Plot a graph of normal displacement vs. shear displacement. This should be on the

same page (same horizontal scale) as the shearing stress vs. shear displacement plot.

6. Using data from all three groups plot shearing stress against normal stress and show

the angle of internal friction, φ, and the intercept, c.


The shear strength parameters of the given soil sample tested in the laboratory are

c = kg/cm2,

= degree

Figure 4.2 Cross-section of a direct shear box test

Direct Shear Test


Plot a graph of Shear Stress vs. Normal Stress. This graph will be approximately a straight

line. The y-intercept of this line gives the cohesion. And the angle of internal friction of the

soil can be determined from the slope of the straight-line. For purely cohesion less soil this

line passes through origin.

n

tan 1


Near any geotechnical construction (e.g. slopes, excavations, tunnels and foundations) there

will be both mean and normal stresses and shear stresses. The mean or normal stresses cause

volume change due to compression or consolidation. The shear stresses prevent collapse and

help to support the geotechnical structure. Failure will occur when the shear stress exceeds

the limiting shear stress (strength). The evaluation of shear parameters is quite important

before initiating any geotechnical construction.

In many engineering problems such as design of foundation, retaining walls, slab bridges,

pipes, sheet piling, the value of the angle of internal friction and cohesion of the soil involved

are required for the design. Direct shear test is used to predict these parameters quickly. The

laboratory report covers the laboratory procedures for determining these values for cohesion

less soils.


1. Preparation of sample should be carried out properly.

2. Sample must be placed in the mould carefully.

3. Each time mould should be properly cleaned with brush.

4. Care should be taken in handling the apparatus.

Direct Shear Test



GENERAL REPORT

DIRECT SHEAR TEST ON SAND

Client Name ________________________

Company Name _____________________

Project Name _______________________

Project No. _________________________

Location of site _____________________

Date of sampling ____________________

Date of testing ______________________

Reporting Name ____________________

Weight of specimen, W ___25 gm______

Normal load, N _____________________

Sample No.___15____________________

Boring No. ______________B-21_______

Depth of sample ___________3 ft_______

Description of Sample Reddish Brown Clay

Tested by __________________________

Comments _________________________

Location ___________________________

Date ______________________________

Normal stress, n ___________________

Proving ring calibration factor __0.15____

Horizontal

Displacement

(1)

Vertical

Displacement

(2)

No. of divisions

in proving ring

dial gauge

(3)

Shear

Force,

S

(4)

Shear stress,

(5)

20 200.152.2

= 6.6 0.264

60 19.8 0.792

135 44.55 1.782

CALCULATIONS

RESULTS

Graph

Plot a graph of shear stress vs. strain; determine the peak stress from the graph, If 20% strain

occurs before the peak stress, then the stress corresponding to 20% strain should be taken as

Shear strength and not the peak shear strength.





Direct Shear Test


n

tan 1

Result

C = (kg/cm2)

=

0

50

100

150

200

250

300

0 5 10 15

Shea

r st

ress

,

(kg/c

m2)

Normal stress n, (kg/cm2)

Direct Shear Test


GENERAL REPORT

DIRECT SHEAR TEST ON SAND

Client Name ________________________

Company Name _____________________

Project Name _______________________

Project No. _________________________

Location of site _____________________

Date of sampling ____________________

Date of testing ______________________

Reporting Name ____________________

Weight of specimen, W ______________

Normal load, N _____________________

Sample No._________________________

Boring No. _________________________

Depth of sample _____________________

Description of Sample ________________

Tested by __________________________

Comments _________________________

Location ___________________________

Date ______________________________

Normal stress, ‘ ___________________

Proving ring calibration factor __________

Horizontal

Displacement

(1)

Vertical

Displacement

(2)

No. of

divisions in

proving ring

dial gauge

(3)

Shear

Force,

S

(4)

Shear stress,

(5)

CALCULATIONS

RESULTS

Direct Shear Test


Displacement

D/R

Horizontal

displacement

D/R × L.C

Corrected area A0=A-B×∆H

Load

D/R

Load S.F=D/R×L.C

shear stress

τ =S.F/A0

Direct Shear Test


Graph





n

tan 1

Result

C = (kg/cm2)

=

One Dimensional Consolidation Test


5 ONE

DIMENSIONAL

CONSOLIDATION

TEST




This test method covers procedures for determining the magnitude and rate of consolidation

of soil when it is restrained laterally and drained axially while subjected to incrementally

applied controlled-stress loading.

This test method is most commonly performed on undisturbed samples of fine grained soils

naturally sedimented in water, however, the basic test procedure is applicable, as well, to

specimens of compacted soils and undisturbed samples of soils formed by other processes

such as weathering or chemical alteration. Evaluation techniques specified in this test method

are generally applicable to soils naturally sedimented in water. Tests performed on other soils

such as compacted and residual (weathered or chemically altered) soils may require special

evaluation techniques.

In case of consolidation settlement of a soil two issues are important i.e. (i) How much the

soil will settle under the application of a particular load and (ii) How long will it take in

settlement. For the latter one it is necessary to know the coefficient of consolidation Cv. To

determine Cv two approaches can be used, one the coefficient of permeability of a soil k, and

the coefficient of volume compressibility mv are known first, then by using

wv

vm

kC

,

where

w is unit weight of water at an ambient temperature.

Plot a graph between Deformations versus Time; the time at different degrees of

consolidation is obtained and by using

t

HTC drv

v

2

the value of Cv for a particular tested soil can be determined.

Where

Tv = Dimensionless time factor

60%U0for 1004

2

UTv

Tv = 1.78 - .933 log (100 – U) For U > 60

U = Degree of Consolidation

Charts are also available for different values of Tv against respective values of

U.

d = Length of the longest drainage path in the soil sample.

22

1 fi

dr

HHH

Hi = Initial sample thickness



Hf = Sample thickness at complete consolidation under a Particular load

t = Time of interest obtained from deformation v/s. time curves.

In square root method where the graph is plotted between dial gauge reading

and square root of t , t 90 is used.

In logarithm method where graph is plotted between dial gauge reading and

Log (t), t50 is used.

In equation (i) the value T is put according to the value of t. If t = tu, then

T = TU. Where, U shows degree of consolidation


PPRREE--CCOONNSSOOLLIIDDAATTIIOONN SSTTRREESSSS,, PP

This is the maximum stress that the soil has “felt” in the past.

CCOOMMPPRREESSSSIIOONN IINNDDEEXX,, CCCC

The compression index, CC, which indicates the compressibility of a normally-consolidated

soil.

RREECCOOMMPPRREESSSSIIOONN IINNDDEEXX,, CCRR

The recompression index, CR, which indicates the compressibility of an over consolidated

soil.

CCOOEEFFFFIICCIIEENNTT OOFF CCOONNSSOOLLIIDDAATTIIOONN,, CCVV

The coefficient of consolidation, CV, which indicates the rate of compression under a load

increment.

NNOORRMMAALLLLYY--CCOONNSSOOLLIIDDAATTEEDD SSOOIILL

A normally-consolidated soil is defined as a soil which, at the present time, is undergoing the

application of a stress that is larger than any stress it has undergone in its history.

That is, '

npresent

OOVVEERR--CCOONNSSOOLLIIDDAATTEEDD SSOOIILL

An over-consolidated soil is defined as a soil which has experienced higher stresses in the

past, '

ppresent



CCOONNSSOOLLIIDDAATTIIOONN

When soil is loaded undrained, the pore pressures increase. Then, under site conditions, the

excess pore pressures dissipate and water leaves the soil, resulting in consolidation

settlement. This process takes time, and the rate of settlement decreases over time.


The consolidation test is used to measure the settlement characteristics of a clay layer.


Consolidation is an important fundamental phenomenon which must be understood by

everyone who attempts to gain knowledge of soil behavior in engineering applications. The

main purpose of consolidation tests is to obtain soil data which is used in predicting the rate

and amount of settlement of structures founded on clay. Although some of the settlement of a

structure on clay may be caused by shear strain; most of it is normally due to volumetric

changes. This is particularly true if the clay stratum is thin compared to the width of the

loaded area or the stratum is located at a significant depth below the structure.


ASTM: D2435-70

AASHTO: T216-66


1. Consolidometer

2. Specimen trimming device

3. Balance sensitive to 0.01 g

4. Stop watch

5. Moisture can

6. Oven




1. Remove covering from sample.

2. Keep track of the sample orientation.

3. Place sample on wax paper disc and glass plate.

4. Rough cut the diameter with a wire saw to within 1/8" of final diameter.

5. Obtain water contents from trimmings

6. Assemble sample in trimmer with extension disc supporting soil.

7. Trim sample with cutting shoe and spatula, obtain second water content.

8. Once sample is completely fitted into specimen ring, trim top and bottom with a

wire saw. Make final cut on top surface with a sharp straight edge.

9. Obtain third and fourth water contents.

10. Use recess tool to create space at top of ring and trim excess soil from bottom with

wire saw. Make final cut with the sharp straight edge.

11. Determine the mass of the specimen and ring (Ms+r

).

12. Measure the recess from the top of ring to the soil surface (ΔHi)

Figure 5.1 One dimensional consolidation apparatus




II NN SS TT RR UU MM EE NN TT SS

55..77..11 AAPPPPAARRAATTUUSS CCAALLIIBBRRAATTIIOONN

1. Assemble the cell (stones, filter paper and top cap).

2. Align assembly in the loading frame.

3. Place a 1 lb seating load on the cell and obtain a zero reading on the displacement

transducer.

4. Apply the same loads to the apparatus as will be used in testing the specimen.

5. At each load increment, record the displacement reading at 15 sec, 30 sec, 1 min, 2

min and 5 min.

6. The change in dial reading gives the machine deflection curve.

55..77..22 AAPPPPAARRAATTUUSS PPRREEPPAARRAATTIIOONN

1. Assemble the Oedometer (stones, filter paper and top cap)

2. Measure the initial z3

(height between top of cap and specimen ring). You can place a

dummy specimen (block of known thickness) between the filter papers for added

height.

3. Disassemble the Oedometer.

4. Grease specimen ring and cutting shoe.

5. Determine the mass (Mr) of the empty specimen ring.

6. Measure the height (Hr) and diameter (D

r) of the ring.

7. Measure the thickness of one piece of filter paper (Hfp

).

8. Cut two pieces of filter paper.

9. Boil or ultrasound the stones for 10 minutes to clean and remove air

10. Cut 2 wax paper disks the diameter of the specimen.

55..77..33 AAPPPPAARRAATTUUSS AASSSSEEMMBBLLYY

1. Fill base with water.

2. Insert bottom stone into base and cover with filter paper.

3. Remove excess water with a paper towel.

4. Place specimen and ring on stone.

5. Cover rim with gasket.

6. Tighten with locking ring.

7. Cover specimen with filter paper and top stone, allow this stone to drain before

placing on soil.

8. Place top cap on stone.



9. Measure z3

with specimen

10. Locate assembly in loading frame with dial gauge and balance arms (this is the true

weight of the assembly which is the tare load).

11. Apply one pound seating load and zero displacement transducer.


1. Consolidate the specimen using a load increment ratio (ΔP/P) between 0.5 and 1.0 for

loading and -0.25 and -0.50 for unloading. Note: recommended schedule S, 0.125,

0.25, 0.5, 1.0, 2, 4, 8, 4, 1, S.

2. Fill the water bath at about 1/4 the overburden stress (0.25 ksi) or within 2 hours.

3. For each increment, record the displacement transducer reading versus time.

Remember that the initial portion of the curve is very important to define the start of

consolidation (εs).

4. During each increment plot both root time and log time curves.

5. Apply increments after the end of primary consolidation has been reached.

6. Allow one cycle of secondary compression to occur under the maximum load and

before the unload-reload cycle.

7. At the end of the test unload the specimen to the seating load and allow time for

swelling.

8. Remove the water from the bath and remove the specimen from the apparatus.

9. Remove any extruded soil and oven dry.

10. Dry the surface of the specimen and determine the mass of both soil and ring.

11. Extrude the soil and obtain water content.

12. Collect washings from filter paper and inside of ring and oven dry.


Initial Specimen Height = Hr – ΔH

i - H

fp

Water Content = (total mass - dry mass)/ dry mass

Note: compute the total mass during the test by subtracting (axial deformation X Area X unit

weight of water) from initial wet mass. This assumes that only water comes out of the

specimen during consolidation.

Void Ratio = (total volume - volume of solids)/ volume of solids

Volume of solids = mass of oven dried soil / specific gravity

Degree of saturation = specific gravity × water content / void ratio



Vertical effective stress (σ'v) (when the pore pressure is zero) = (Applied load - Tare load +

top cap and stone)/ Area

Vertical strain (εv) = (measured axial deformation - Apparatus compression)/ Initial specimen

height

Note: The Apparatus compression curve is attached to this assignment

Compressibility (av) = - change in void ratio / change in vertical stress

Note: change in void ratio is usually taken at the end of primary but for this laboratory

assignment you can use end of increment values.

Coefficient of consolidation (CV). (Root time) = 0.848 (drainage height) 2

/ time for 90%

consolidation

Coefficient of consolidation (CV). (Log time) = 0.197 (drainage height) 2

/ time for 50%

consolidation

Note: Drainage height is computed at 50% consolidation for both cases.

Hydraulic conductivity (kV) = (coefficient of consolidation compressibility unit weight

of water) / (1 + average void ratio)

Rate of secondary compression (cα) = change in strain per log cycle of time after primary is

complete

Square root or time vs. Dial gauge reading




The value of coefficient of consolidation is found to be _________

By square root method _________


In engineering practice, reasonably good predictions of a structure’s settlements can be made

from the results of carefully run laboratory tests. Predicted settlements are larger than actual

settlements more often than not. Time rate predictions are often rather poor in practice. Better

predictions, naturally, can be made for those cases which have conditions more closely in

agreement with the assumptions made in the theory derivation. This would be the case, for

example, when the soil involved experiences most of its settlement due to primary

consolidation, or when drainage conditions in the field are accurately known.


1. Handling of instrument must be with care.

2. Readings should be note down carefully.




GENERAL REPORT

CONSOLIDATION TEST

(Time vs. vertical dial reading)

Client Name ________________________

Company Name _____________________

Project Name _______________________

Project No. _________________________

Location of site _____________________

Date of sampling ____________________

Date of testing ______________________

Reporting Name ____________________

Pressure on specimen ________________

Sample No. _________B-24___________

Boring No. _________________________

Depth of sample ____2 ft______________

Description of Sample _____silty_______

Tested by __________________________

Comments. _________________________

Location ___________________________

Date ______________________________

Clock time of load application __________

Time after load

application

t

(min)

(t)1/2

(min 0.5

)

Vertical dial

reading

(in)

9:15 AM 0 0

09:15.1 0.1 0.316228

9:15:25 0.25 0.5

09:15.5 0.5 0.707107

9:16 1 1

9:17 2 1.414214

9:19 4 2

9:23 8 2.828427

9:30 15 3.872983

9:45 30 5.477226

10:15 60 7.745967

11:15 120 10.95445

1:15 PM 240 15.49193

5:15 480 21.9089

8:15 AM 1380 37.14835

CALCULATIONS

RESULT



GENERAL REPORT

CONSOLIDATION TEST

(Void ratio-pressure and coefficient of consolidation calculation)

Client Name ________________________

Company Name _____________________

Project Name _______________________

Project No. _________________________

Location of site _____________________

Date of sampling ____________________

Date of testing ______________________

Reporting Name ____________________

Specimen diameter __________________

Moisture content: beginning of test __ (%)

Weight of dry soil specimen ___________

Sample No._________________________

Boring No. _________________________

Depth of sample _____________________

Description of Sample ________________

Tested by __________________________

Comments _________________________

Location ___________________________

Date ______________________________

Initial specimen height, Ht(i)___________

Moisture content: End of test ________(%)

Gs ___ Height of solids, Hs_________ cm

Pressure

P

(T/ft2)

Final

Dial

Reading

(in)

Change

in

specimen

height

(in)

Final

specimen

Height

Ht(f)

(in)

Height

of void

Hv

(in)

Final

void

ratio

e

Average

height during

consolidation,

Ht(av)

(in)

Fitting time

(sec)

cv from

x

103(in2/sec)

t90

t50

t90

t50

CALCULATIONS

RESULTS



Dial Readings vs Time

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0.1 1 10 100 1000 10000

Time (min)D

efo

rma

tio

n d

ial re

ad

ing




CONSOLIDATION TEST

(Void ratio-pressure)

Void Ratio

Initial void ratio, eo 1.248781

Volume of solid in specimen, Vs 27.90809

Area of specimen, A (cm2) 31.67736

Height of solid in specimen, Hs (cm) 0.881011

Pressure,

P(tons/ft2)

Initial

deformation

dial reading at

beginning of

first loading(in.)

Deformation dial

reading

representing

100% primary

consolidation, (in.)

Change in thickness of

specimen, ΔH(cm)

Change in

void ratio, De

[Δe=ΔH/ Hs]

Void Ratio,

e (e=eo-Δe)

5 6 7 (8)=((7)-(6))*2.54 (9)=(8)/(4) (10)=(1)-(9)

0 0 0 0 0 1.25

0.4 0 0.0158 0.04013 0.04555 1.204447

0.8 0 0.0284 0.07214 0.08188 1.16812

1.6 0 0.049 0.12446 0.14127 1.108729

3.2 0 0.0761 0.19329 0.2194 1.030597

6.4 0 0.1145 0.29083 0.33011 0.919886

12.8 0 0.158 0.40132 0.45553 0.794472



(Coefficient of consolidation calculation)

Pressure,

P,

(tons/ft2)

Initial

height of

specimen

at

beginning

of test, Ho

(in)

Deformation

dial reading

at 50%

consolidation

(in)

Thickness of

specimen at

50%

consolidation,

(in)

Half

thickness of

specimen at

50%

consolidation

(in)

Time for 50%

consolidation

(min)

Coefficient of

consolidation

(in2/min)

(1) (2)

(3)

(from dial

reading vs

log of time

curves)

(4)=(2)-(3) (5)=(4)/2

(6)

(from dial

readings

versus log of

time curves)

(7)=0.196(5)2/(6)

0 0.78

0.4 0.78 0.0108 0.7692 0.3846 8.2 0.003536

0.8 0.78 0.0233 0.7567 0.37835 6.4 0.004384

1.6 0.78 0.0398 0.7402 0.3701 4 0.006712

3.2 0.78 0.0644 0.7156 0.3578 3.4 0.00738

6.4 0.78 0.0982 0.6818 0.3409 3.5 0.006508

12.8 0.78 0.1387 0.6413 0.32065 4 0.005038



Result

The value of coefficient of consolidation is found to be

By square root method =

By logarithm method =




CONSOLIDATION TEST

Specimen Data

At beginning of test

Type of specimen(checked one)

undisturbed

remolded

Diameter of specimen, D( in.)

Area of specimen , A in.2

Initial height of specimen, Ho ( in.)

Initial volume of specimen (in.3)

Weight of specimen ring +specimen (g)

Weight of specimen ring (g)

Initial wet weight of specimen (g)

Initial wet unit weight

Initial moisture content (%)

Can no.

Weight of wet soil + can (g)

Weight of dry soil + can (g)

Weight of can (g)

Weight of water (g)

Weight of dry soil (g)

Initial moisture content (g)

Initial dry weight of specimen (computed) (g)

Specific gravity of soil



Volume of solid in soil specimen cm3

Volume void in soil specimen cm3

volume of water in soil specimen cm3

(Note: Unit weight of water = 1 g/cm3)

Initial degree of saturation

At the End of test

Can no.

Weight of can + wet specimen removed from

Consolidometer (g)

Weight of can + oven dried specimen (g)

Weight of can (g)

Final weight of water in specimen

Final dry weight of specimen

Final moisture content

Final degree of saturation %

Initial void ratio

Volume of solid in specimen cm3

Initial volume of specimen cm3

Initial volume of void in specimen cm3

Initial void ratio, eo



(Time vs. vertical dial reading)

Pressure on specimen

Clock time of load application

Time after load application

t

(min)

(t)1/2

(min 0.5

)

Vertical dial

reading

(in)




CONSOLIDATION TEST

(Void ratio-pressure)

Void Ratio

Initial void ratio, eo

Volume of solid in specimen, Vs

Area of specimen, A (cm2)

Height of solid in specimen, Hs (cm)

Pressure,

P

(tons/ft2)

Initial

deformation dial

reading at

beginning of

first loading

(in)

Deformation dial

reading

representing

100% primary

consolidation,

(in)

Change in thickness

of specimen,

ΔH

(cm)

Change in void

ratio,

De [Δe=ΔH/ Hs]

Void Ratio,

e (e=eo-Δe)

(5) (6) (7) (8)=((7)-(6))2.54 (9)=(8)/(4) (10)=(1)-(9)



(Coefficient of consolidation calculation)

Pressure,

P,

(tons/ft2)

Initial height of

specimen at

beginning of

test, Ho

(in)

Deformation

dial reading at

50%

consolidation

(in)

Thickness of

specimen at

50%

consolidation,

(in)

Half thickness

of specimen at

50%

consolidation

(in)

Time for 50%

consolidation

(min)

Coefficient of

consolidation

(in2/min)

(1) (2)

(3)

(from dial

reading vs log of

time curves)

(4)=(2)-(3) (5)=(4)/2

(6)

(from dial

readings versus

log of time curves)

(7)=0.196(5)2/(6)

Result

The value of coefficient of consolidation is found to be

By square root method =

By logarithm method =

Standard Penetration Test


6 STANDARD

PENETRATION

TEST




If the test is to be carried out in gravelly soils the driving shoe is replaced by a solid 600 cone.

There is evidence that slightly higher results are obtained in the same material when the

normal driving shoe is replaced by the 600 cone.

The Standard Penetration Test was developed around 1927. It is estimated that 85% to 90%

of conventional foundation design in North and South America is made using the SPT. This

dynamic penetration test is used to assess the density index and to determine the bearing

capacity of a sand deposit. This dynamic penetration test is used to assess the density index

and to determine the bearing capacity of a sand deposit.

The test is performed using a split barrel sampler, 50 mm external diameter, 35 mm internal

diameter and about 450 mm (18in) in length, connected to the end of boring rods. The

sampler is driven into the sand at the bottom of a cased borehole by means of 65 kg hammer

falling freely through a height of 760 mm (30 in) onto the top of the boring rods.

Figure 6.1 Arrangement of SPT

Different methods of releasing the hammer are used in different countries. The borehole must

be cleaned out to the required depth, care must be taken to ensure that the material to be

tested is not distributed: jetting, as part of the boring operation is undesirable. The casing

must not be driven below the level at which the test is to begin.



Initially the sampler is driven 150mm (6in) into the sand to seat the device and to bypass any

disturbed sand at the bottom of the borehole. The number of blows required to drive the

sampler a further 300 mm (12in) is then recorded: this number is called the standard

penetration resistance (N). The number of blows required for each 150 mm (6in) of

penetration (including the initial drive) should be recorded separately. If 50 blows are

reached before a penetration of 300mm (12in), no further blows should be applied but the

actual penetration should be recorded. At the conclusion of a test the sampler is withdrawn

and the sand extracted. Tests are normally carried out at interval of b/w 0.75 and 1.5m to a

depth below foundation level at least equal to the width (B) of the foundation

66 .. 22 OO BB JJ EE CC TT OO FF TT EE SS TT

To determine the load bearing capacity of soils by standard penetration test. The object of the

test is to determine the relative density and bearing capacity of granular sandy soils.


This test method describes the procedure, generally known as the Standard Penetration Test

(SPT), for driving a split-barrel sampler to obtain a representative soil sample and a measure

of the resistance of the soil to penetration of the sampler.

This standard does not purport to address all of the safety problems, if any, associated with

its use. It is the responsibility of the user of this standard to establish appropriate safety and

health practices and determine the applicability of regulatory limitations prior to use.

Figure 6.2 Equipment as mentioned under heading




ASTM: D1586


The test equipment consists of:

1. Standard split-barrel Sampler (Split-spoon)

2. A casing or Drilling.

3. A thick wall Split tube Sampler, with 2” (5.08cm) OD and 1.5” (3.5cm) ID having the

tube length of 18” to 24” long.

4. Guide rod. (30” or 76cm length)

5. Hammer having weight of 140lb (623N)

6. Rope.

7. Tripods

8. Steel chain (3m approx)

9. Lever support and rod

10. Pipe wrench and chain wrench

11. Pulley



Figure 6.3 Solid tube sampler and driving sample




1. Attach the Standard split-barrel Sampler (Split-spoon) to the bottom of the drilling

rod. The top of the drilling rod is attached by anvil used to transfer the hammer load

to the drilling rod. The anvil connects a guide rod passing through the drop hammer.

2. Erect the tripod so that each leg must form an angle of 1200 with respect to the other

and at equidistant from the center mark. Hookup pulley to the tripod with a rope

passing over it, and connect one end of the rope with drop hammer to lift it up.

3. Excavate a circular or rectangular trench upto the required foundation depth (below

which the bearing capacity of the soil is required) at the center mark..

4. Gradually pull the other end of the rope (manually or by some mechanical

arrangements) to erect the sampler. Make sure that the sampler assembly is vertically

erected at the center mark of the testing spot in excavation.

5. Now pull the rope slowly to lift the drop hammer to the full height of the guide rod

(76cm approximately) and then suddenly release the rope to provide free fall to the

hammer repeatedly to drive the Standard split-barrel Sampler (Split-spoon) 18" into

the soil.

6. After driving the sampler 18" into the soil count the number of blows, which are

required to penetrate each of three 6" increments separately. The Standard Penetration

Resistance value (N-value) is the number of blows required to penetrate the last 12",

thus the N-value represents the number of blows per foot.

7. After blow counts have been obtained, remove and open the split–spoon Sampler to

obtain a disturbed sample for subsequent examination and testing.

8. Determine the specific weight of the soil on the spot of the boring log to obtain the

effective overburden pressure.


Relation between N and (peck, 1974)

Corrected N 5 10 15 20 25 30 35 40 45 50

28.5 30 32 33 35 36 37.5 39 40 43

Allowable bearing capacity using N-values

66..77..11 TTEERRZZAAGGHHII AANNDD PPEECCKK MMEETTHHOODD

Terzaghi and Peck (1948) recommended that N values should be determined between

foundation level and a depth of approximately B below the foundation. They proposed a

correlation between allowable bearing capacity and the corrected N-values in the form of a

chart. The breadth of footing and the corrected N-value are used as entry data and the



allowable bearing capacity (qTP) is read off the left vertical axis. For Correction there is also

a formula, which is given as follow:

`

2000 log77.0

NC

The effect of the water table may be taken into account by applying the following correction

BD

D1

2

1C w

w

Where

Dw = Depth of water table below the surface.

D = Foundation depth below the surface.

B = Footing breadth.

Thus,

TPwa qCq

The Terzaghi and Peck method yields quite conservative values of qa, since it attempts to

ensure that the settlement is nowhere greater than 25mm, for wide footings and rafts the

limiting values may be raised to 50 mm. The qTP value is the function of SPT resistance value

N, and the breadth of footing. The required graph can be found in any Soil Mechanics Text

Book.

66..77..22 MMEEYYEERRHHOOFF MMEETTHHOODD

Meyerhof (1965) suggested that the qTP value could be increased by 50 % and that no

correction should be made for the water table since the effect would be incorporated in the

measured N-values. Meyerhof also proposed a set of simple design relationships as follows:

1.25mBfor 9.1

Ns

q La

:raftsfor 84.2

1.25mBfor 33.0

84.2

2

Nsq

B

BNsq

La

La

Where

SL = permitted settlement limit (mm).

N = average N-values between z = D and z = D + B.

B = breadth of footing.

66..77..33 BBUURRLLAANNDD AANNDD BBUURRBBIIDDGGEE MMEETTHHOODD

Burland and Burbidge (1985) using a large number of settlement observations concluded that

the depth of the zone of influence must be considered in which 75% of the settlement will

occur and which may be taken approximately as: Bln77.0

i eZ



Thus the average measured N-value is therefore taken between Z = D and Z = D + Zi

The compressibility of soil is stated in terms of average N-value as a grade of compressibility

and compressibility index as follow

4.1cN

71.1I

The allowable bearing capacity of soil is thus will be given as follow

`3

2

IB

Sq

c7.0

La

` is the effective overburden pressure measured from top surface to the depth of foundation.


SL = ____________,

B = _____________,

Nav = ___________

No. Method Bearing Capacity Average

1 Terzaghi and Peck

2 Meyerhof

3 Burland and Burbidge



66 .. 99 SS AA MM PP LL EE PP RR OO BB LL EE MM


STANDARD PENETRATION TEST

Sample No. 15 Project No. SR 2828





Specimen diameter cm

Depth (z) 3.5’ (1.07m)

No. of

Blows

per 6”

1st 8

2nd 16

3rd 27

N 16 + 27=43

(KN/m2) 19

z (KN/m2) 20.27

wzu 0

u` (KN/m2) 20.27

`

2000log77.0

NC

1.536

N` =CN N 66.027

Average: N 66.027

SL = 25.1 mm

B = 1.06 m

Nav = 66

No. Method Bearing Capacity Average

1 Terzaghi and Peck 1320 KN/m2

2485.8KN/m2 2 Meyerhof 882.6 KN/m

2

3 Burland and Burbidge 5254.9 KN/m2)




STANDARD PENETRATION TEST


Boring No. Location

Depth of sample


Tested by Date

Specimen diameter cm

Depth (z)

No. of

Blows

per 6”

1st

2nd

3rd

N

z

wzu

u`

CN =

`

2000log77.0

N` =CN N

Aver: N

Result

SL =

B =

Nav =

Unconfined Compression Test


7 UNCONFINED

COMPRESSION

TEST




When the method of testing tube-recovered cohesive soil sample compression was first

introduced, it was widely accepted as a means of rapidly evaluating the shear strength of a

soil. From Mohr’s circle construction; it is evident that the shear strength or cohesion of a

soil sample can be approximate where qu is always used as the symbol for the unconfined

compressive strength of the soil. This computation is based on the fact that the minor

principal stresses 3 are zero (atmospheric), and the angle of internal friction of the soil is

assumed zero. With more knowledge concerning soil behavior available, it became evident

that the unconfined compression test does generally provide a very reliable value of soil

shear strength for at least three reasons:

1. The effect of lateral restraint provided by the surrounding soil mass on the sample is

lost when the sample is removed from the ground. There is, however, some opinion

that the soil moisture is provides a surface tension (or confining) effect so that the

sample is somewhat “confined”. This effect should be more pronounced if the sample

is saturated or nearly so. This effect will depend also on the relative humidity of the

testing area making a quantitative evaluation of it rather difficult.

2. The internal soil condition (the degree of saturation, the pore water pressure under

stress deformation, and the effects of altering the degree of saturation) cannot be

controlled.

3. The friction on the end of the sample from the loading platens provides a lateral

restraint on the ends, which alters the internal stresses, an unknown amount.

Table 7.1 Relative consistency as a function of unconfined compressive strength

Consistency qu (lb/ft2)

Very soft <250

Soft 250-500

Medium 5000-1000

Stiff 1000-2000

Very stiff 2000-4000

Hard >4000


UUNNCCOONNFFIINNEEDD CCOOMMPPRREESSSSIIVVEE SSTTRREENNGGTTHH

The compressive stress at which an unconfined cylindrical specimen of soil will fail in a

simple compression test. In this test method, unconfined compressive strength is taken as the

maximum load attained per unit area or the load per unit area at 15% axial strain, whichever

is secured first during the performance of a test.



SSHHEEAARR SSTTRREENNGGTTHH

The shear strength of soil is the resistance to deformation by continuous shear displacement

of soil particles or on masses upon the action of shear stress.

For unconfined compressive strength test specimens, the shear strength is calculated to be ½

of the compressive stress at failure.


This method determines the unconfined compressive strength (qu) of the soil sample.


This test method covers the determination of the unconfined compressive strength of

cohesive soil in the undisturbed, remolded, or compacted condition, using strain-controlled

application of axial load.

This test method provides an approximate value of the strength of cohesive soils in terms of

total stresses.

This test method is applicable only to cohesive materials which will not expel bleed water

(water expelled from the soil due to deformation or compaction) during the loading portion

of the test and which will retain intrinsic strength after removal of confining pressures, such

as clays or cemented soils. Dry and crumbly soils, fissured or varved materials, silts, peats,

and sands cannot be tested with this method to obtain valid unconfined compressive strength

values.

This test method is not a substitute for AASHTO T 234-85 which is ‘Strength Parameters of

Soils using Triaxial Compression’.

The values stated in SI units are to be regarded as the standard. The values stated in inch-

pound units are approximate.


ASTM: D2166-66

AASHTO: 208-70


1. Unconfined compression testing machine (Triaxial Machine)

2. Specimen preparation equipment

3. Sample extruder

4. Balance




77..66..11 PPRREEPPAARRAATTIIOONN OOFF UUNNDDIISSTTUURRBBEEDD SSAAMMPPLLEE

1. Obtain a sample and using the wire saw and miter box, trim the ends parallel to each

other.

2. Place the sample in the soil lathe and trim it to a circular cross-section.

3. Reposition the sample in the miter box and cut it to a length of approximately 7 cm

by trimming both ends.

4. Measure the average length and diameter of the sample using the veneer caliper.

Weigh the sample.

5. Use the sample trimmings to determine water content of the clay.

77..66..22 PPRREEPPAARRAATTIIOONN OOFF RREEMMOOUULLDDEEDD SSAAMMPPLLEE

1. Remold the clay thoroughly.

Figure 7.1 Unconfined Compression Testing Device



2. Reform a cylindrical specimen using the sample former, taking care not to entrap air

in to the clay.

3. Extrude the sample from the mould and square its ends using the miter box.

4. Measure the sample as before.


II NN SS TT RR UU MM EE NN TT SS

Standard Geotest unconfined compression machines are supplied with a double proving ring

or load cell and digital display which reads directly to 0.1 lbf or 1N and have a peak hold.

Proving ring models include a calibration chart in both pounds and SI units. Pounds will be

supplied unless SI units are specified. Strain is measured with a 1" travel (25mm on SI

versions) dial indicator. 2" (50mm) dial indicators or EDDIs can replace dial indicator as an

added option.


1. Remolded specimens are prepared in the laboratory depending on the proctors data at

the required molding water content.

2. If testing undisturbed specimens retrieved from the ground by various sampling

techniques, trim the samples into regular triaxial specimen dimensions (2.8” x 5.6”)

3. There will be a significant variation in strength of undisturbed and remolded samples.

4. Measure the diameter and length of the specimen to be tested

5. If curing the sample (treated soils), wrap the samples in a geotextile and then a zip

bag. Place the sample in a humidity room maintained at a relative humidity of 90%

6. Prior to testing, avoid any moisture loss in the sample, place on a triaxial base

(acrylic). The ends of the sample are assumed to be frictionless

7. The triaxial cell is placed above the sample and no confinement is applied

8. The rate of strain is maintained at 1.2700 mm/min as per ASTM specifications.

9. The data acquisition system collects real time data and the test is stopped when there

is a drop observed in the strain versus load plot


Calculate the water contents, Axial load (P = Load Ring Reading x [Calibration of

load ring]), strain ( = ΔL/L0 x 100%), instantaneous area (Ai = A0/(1- ), where is

in decimal format), and σ1 = P/A.




Plot a graph of σ 1 or the deviator stress as ordinate vs. ez or vertical strain in % as

abscissa on Cartesian graph paper. Define qu at failure; this is s1 (peak).


1. The test results provide an estimate of the relative consistency of the soil as can be

seen in Table 6.1.

2. Almost used in all geotechnical engineering designs (e.g. design and stability

analysis of foundations, retaining walls, slopes and embankments) to obtain a rough

estimate of the soil strength and viable construction techniques

3. To determine Undrained Shear Strength or Undrained Cohesion (Su or Cu) = qu/2

4. The unconfined compression test is usually made on undisturbed samples. It is

reasonably simple and rapid to perform. It gives a very good measure of the shearing

strength of cohesive soils. In somewhat granular soil its application is limited, but it

does provide a good supplementary test for more complex strength tests.

5. The unconfined compression test is limited in that test conditions can be varied very

little. Hence, the test may provide a good measure of the in-situ strength, but may

provide only limited strength data, as the stress conditions change due to loading or

construction.


1. Scale must be precise.

2. Width of groove must be accurate.

3. Depth of groove must be accurate.

4. Handle of turning pace should be done with care.

5. Length of closure should be of ½ inch

Figure 7.2 Failure patterns typical of brittle specimen





UNCONFINED COMPRESSION TEST Sample No. 15 Project No. SR 2828





Proving ring calibration factor 6000 (lb/in)

Specimen

deformatio

n = L

(in)

Vertical

strain

= L / L

Proving

ring dial

reading

[No. of

small

divisions]

Load =

(Col. 3)

calibration

factor

(lb)

Corrected

area =

1

AA 0

c

(in2)

Stress =

(col.4)/(col.5)

(lb/in2) or kPa

(1) (2) (3) (4) (5) (6)

0 0 0 0 4.91 0

0.025 0.004181 0.0024 14.4 4.930613 2.920529

0.05 0.008361 0.0058 34.8 4.9514 7.028316

0.075 0.012542 0.0086 51.6 4.972362 10.37736

0.1 0.016722 0.0116 69.6 4.993503 13.93811

0.125 0.020903 0.015 90 5.014825 17.94679

0.15 0.025084 0.0176 105.6 5.036329 20.96765

0.175 0.029264 0.0208 124.8 5.058019 24.67369

0.2 0.033445 0.0224 134.4 5.079896 26.45723

Result

Plot a graph of s1 or the deviator stress as ordinate vs. ez or vertical strain in % as abscissa on

Cartesian graph paper. Define qu at failure; this is s1 (peak).



Relationship between load per unit

area and unit strain

0

5

10

15

20

25

30

0 5 10 15

Unit Strain (in/in)

Lo

ad

Per

Un

it A

rea

(lb

/in

2)




UNCONFINED COMPRESSION TEST


Boring No. Location

Depth of sample


Tested by Date

Specimen

deformatio

n = L

(in)

Vertical

strain

= L / L

Proving

ring dial

reading

[No. of

small

divisions]

Load =

(Col. 3)

calibration

factor

(lb)

Corrected

area =

1

AA 0

c

(in2)

Stress =

(col.4)/(col.5)

(lb/in2) or kPa

Result

Plot a graph of s1 or the deviator stress as ordinate vs. or vertical strain in % as abcissa on

Cartesian graph paper. Define qu at failure; this is s1 (peak).

Triaxial Test


8 TRIAXIAL TEST

Triaxial Test



From an inspection of the triaxial apparatus, it is concluded that any soil pore-fluid state, from

a negative or vacuum state to a fully saturate state with an excess pore-fluid pressure, can be

obtained with this equipment. Drained or undrained conditions can be investigated. For a

drained test, as the load is applied to the soil specimen, one can allow the pore fluid to escape

by opening the appropriate valve. An undrained test can be performed by closing the soil

system to the atmosphere so that no pore fluid can escape during the test.


UUNNCCOONNSSOOLLIIDDAATTEEDD--UUNNDDRRAAIINNEE TTEESSTT

Which is also called the quick test (abbreviation commonly used are UU and Q test). This test

is performed with the drain valve closed for all phases of the test. Axial loading is commenced

immediately after the chamber pressure σ3 is stabilized.

CCOONNSSOOLLIIDDAATTEEDD--UUNNDDRRAAIINNEEDD TTEESSTT

Also termed consolidated-quick test or R test (abbreviated CU or R). In this test, drainage or

consolidation is allowed to take place during the application of the confining pressure σ3.

Loading does not commence until the sample ceases to drain (or consolidate). The axial load

is then applied to the specimen, with no attempt made to control the formation of excess pore

pressure. For this test, the drain valve is closed during axial loading, and excess pore pressures

can be measured.

CCOONNSSOOLLIIDDAATTEEDD--DDRRAAIINNEEDD TTEESSTT

Also called slow test (abbreviated CD or S). In this test, the drain valve is opened and is left

open for the duration of the test, with complete sample drainage prior to application of the

vertical load. The load is applied at such a slow strain rate that particle readjustments in the

specimen do not induce any excess pore pressure.

Since there is no excess pore pressure total stresses will equal effective stresses. Also the

volume change of the sample during shear can be measured.


Determination of shear parameters of soils by triaxial test.


Scope of this test is to determine the shear parameters, strength-deformation characteristics

pore water pressure, etc.

Triaxial Test


From an inspection of the triaxial apparatus, it is concluded that any soil pore-fluid state, from

a negative or vacuum state to a fully saturate state with an excess pore-fluid pressure, can be

obtained with this equipment. Drained or undrained conditions can be investigated. For a

drained test, as the load is applied to the soil specimen, one can allow the pore fluid to escape

by opening the appropriate valve. An undrained test can be performed by closing the soil

system to the atmosphere.

88 .. 44 SS TT AA NN DD AA RR DD DD EE SS II GG NN AA TT II OO NN

ASTM: D2850-70

AASHTO: 234-70

Figure 8.1 Schematic diagram of triaxial test

Triaxial Test



1. Triaxial cell.

2. Strain controlled compression machine (Figure 7.1)

3. Specimen trimmer

4. Wire saw

5. Vacuum source

6. Oven

7. Evaporating membrane

8. Calipers

9. Rubber membrane

10. Membrane stretcher

Figure 8.2 Triaxial test device

Triaxial Test



88..66..11 PPRREEPPAARRAATTIIOONN OOFF UUNNDDIISSTTUURRBBEEDD SSAAMMPPLLEE

1. Obtain a sample and using the wire saw and miter box, trim the ends parallel to each

other.

2. Place the sample in the soil lathe and trim it to a circular cross-section.

3. Reposition the sample in the miter box and cut it to a length of approximately 7 cm by

trimming both ends.

4. Measure the average length and diameter of the sample using the veneer caliper.

Weigh the sample.

5. Use the sample trimmings to determine water content of the clay.

88..66..22 PPRREEPPAARRAATTIIOONN OOFF RREEMMOOUULLDDEEDD SSAAMMPPLLEE

1. Remold the clay thoroughly.

2. Reform a cylindrical specimen using the sample former, taking care not to entrap air in

to the clay.

3. Extrude the sample from the mould and square its ends using the miter box.

4. Measure the sample as before.


88..77..11 PPLLAACCEEMMEENNTT OOFF SSPPEECCIIMMEENN IINN TTHHEE TTRRIIAAXXIIAALL TTEESSTTIINNGG MMAACCHHIINNEE

1. Boil the two-porous stones to be used with the specimen.

Figure 8.3 Triaxial test apparatus

Triaxial Test


2. De-air the lines connecting the base of the Triaxial cell

3. Attach the bottom platen to the base of the cell

4. Place the bottom porous stone (moist) over the bottom platen.

5. Take a thin rubber membrane of appropriate size to fit the specimen tightly. Take a

membrane stretcher, which is a brass tube with an inside diameter of about ¼ in

(6mm) larger than the specimen diameter. The membrane stretcher can be connected

to a vacuum source. Fit the membrane to the inside of the membrane stretcher, and lap

the ends of the membrane over the stretcher. Then apply the vacuum. This will make

the membrane form a smooth cover inside the stretcher.

6. Slip the soil specimen to the inside of the stretcher with the membrane (step5) the

inside of the membrane may be moistened for ease of slipping the specimen in. Now

release the vacuum, and unroll the membrane-form the ends of the stretcher.

7. Place the specimen (step 6) on the bottom porous stone (which is placed on the bottom

platen of the Triaxial cell), and stretch the bottom end of the membrane around the

porous stone and bottom platen. At this time, place the top porous stone (moist) and

the top platen on the specimen, and stretch the top of the membrane over it. For

airtight seals, it is always a good idea to apply some silicone grease around the top and

bottom plates before the membrane is stretched over them.

8. Using some rubber bands, tightly fasten the membrane around the top and bottom

platens.

9. Connect the drainage line leading from the top platen to the base of the triaxial cell.

10. Place the Lucite cylinder from the top platen to the base triaxial cell on the base plate

to complete the assembly.

Note

1. In the Triaxial cell, the specimen can be saturated by connecting the drainage line

leading to the bottom of the specimen to a saturation reservoir. During this process, the

drainage line leading from the top of the specimen is kept open to the atmosphere. The

saturation of clay specimens takes a fairly long time.

2. For unconsolidated undrained test, if the specimen saturation is not required,

nonporous plates can be used instead of porous stones at the top and bottom of the

specimen.

88..77..22 UUNNCCOONNSSOOLLIIDDAATTEEDD-- UUNNDDRRAAIINNEEDD TTEESSTT

1. Place the Triaxial cell (with the specimen inside it) on the platform of the compression

machine.

2. Make proper adjustment so that the piston of the triaxial cell just rests on the top

platen of the specimen.

3. Fill the chamber of the triaxial cell with water. Applying a hydrostatic pressure, 3, to

the specimen through the chamber fluid. (Note: All drainage to and from the specimen

should be closed now so that drainage from the specimen does not occur).

4. Check for proper contact between the piston and the top platen on the specimen. Zero

the dial gauge of the proving ring and the gauge used for measurement of the vertical

compression of the specimen. Set the compression machine for a strain rate of about

0.5% per minute, and turn the switch on.

Triaxial Test


5. Take proving ring dial readings for vertical compression intervals of 0.01inch

(0.254mm) initially. This interval can be increased to 0.02 inch (0.508mm) or more

later when the rate of increase of loads on the specimen decreases. The proving ring

readings will increase to a peak value and then may decrease or remain approximately

constant. Take about four to five readings after the peak point.

6. After completion of the test, reverse the compression machine and lower the triaxial

cell, and then shut off the machine. Release the chamber pressure, and drain the water

in the triaxial cell. Then remove the specimen and determine its moisture content.


1. Compute the unit strain from the deformation readings as

2. Δax = ΔL/L0 and fill in the appropriate column of the data sheet. Also compute the

adjusted instantaneous area A = Ac/ (1-Δax) and place this in the appropriate column

of the data sheet. The c subscript above refers to the fact that these should be the

dimensions not at the start of the test, but after consolidation of the specimen.

3. Compute the axial load using the load readings. If a load (proving) ring is used, the

load P is P = DR x load-ring constant where DR is the load-dial reading in units of

deflection. Put these data in the appropriate column of the data sheet.

4. Compute the principal stress difference

5. (σ1 - σ3) = P/A and fill in the appropriate column of the data sheet.

6. Knowing that

7. σ1 = σ3 + (σ1 - σ3)

8. Compute the principal stress ratio: σ1/σ3


1. Draw a graph of the axial strain (%) vs. deviatory stress. From this graph, obtain the

value of at failure ( = f)

2. The minor principal stress on the specimen at failure is 3 (i.e. the chamber confining

pressure). Calculate the major principal stress at failure as

31

3. Draw a Mohr’s circle with 1 and 3 as the major and minor principal stresses. The

radius of the Mohr’s circle is equal to Su.

Triaxial Test



Triaxial test is a soils laboratory test to determine shear strength parameters. The shear

strength of soil is needed to design foundation, slopes, tunnels, dams, and other geotechnical

systems. It is a most widely used technique of determining the shear strength of soils.

Chart 8.2 Showing results of triaxial test

Chart 8.1 Showing stress vs strain curve

0

2

4

6

8

10

12

14

16

0 2 4 6 8 10 12 14

Str

ess

chan

ge

lb/i

n2

Axial strain %

Triaxial Test


The sample, which is cylindrical, is tested inside a Perspex cylinder filled with water under

pressure. The sample under test is enclosed in a thin rubber membrane to seal it from the

surrounding water. The pressure in the cell is raised to the desired value, and the sample is

then brought to failure by applying an additional vertical stress.

One of the major advantages of the triaxial apparatus is the control provided over drainage

from the sample. When no drainage is required (i.e. in undrained tests), solid end caps are

used. When drainage is required, the end caps are provided with porous plates and drainage

channels. It is also possible to monitor pore-water pressures during a test.


1. Limit the magnitude of the excess pore pressure by testing at a very slow strain rate, as

it is impossible to have a state of no excess pore pressure

2. A drain test can take up to a week. For this duration, membrane leaks, soil set up and

equipment corrosion can be significant.

Triaxial Test




UNCONSOLIDATED UNDRAINED TRIAXIAL TEST

(Preliminary data)

Sample No. 15

Project No. SR 2828

Boring No. B-21

Location Newell, N.C



Tested by John Doe

Date 1/26/89

Moist unit weight of specimen (beginning of test) 122.7 lb/ft3

Moisture content (end of test) 16.9 (%)

Dry unit weight of specimen 105.0 lb/ft3

Initial average length of specimen, Lo 5.82 cm

Initial average diameter of specimen, Do 2.50 cm

Initial area, Ao 4.91 cm2

Gs 2.78

Final degree of saturation 71.9 %

Cell confining pressure, σ3 10.0 psi

Proving ring calibration factor 6000 lb/in

Triaxial Test



UNCONSOLIDATED-UNDRAINED TRIAXIAL TEST

(Axial stress – strain calculation)

Specimen

deformation

= δL

(in)

Vertical

strain,

є = δL

L

Proving

ring dial

reading

Piston Load,

col.3 x c.f

(calibration

factor)

(lb)

Corrected area

=

Ac = Ao /1 – є

(in2)

Deviatory

Stress

Δσ = P/Ac

(lb/in2)

(1) (2) (3) (4) (5) (6)

0 0 0 0 4.91 0

0.005 0.0009 0.0012 7.2 4.91 1.5

0.01 0.0017 0.0025 15 4.92 3

0.015 0.0026 0.0037 22.2 4.92 4.5

0.02 0.0034 0.0053 31.8 4.93 6.5

0.025 0.0043 0.0066 39.6 4.93 8

0.05 0.0086 0.0140 84 4.95 17

0.075 0.0129 0.0201 120.6 4.97 24.3

0.100 0.0172 0.0256 153.6 5.00 30.7

0.125 0.0215 0.0294 176.4 5.02 35.1

0.150 0.0258 0.0321 192.6 5.04 38.2

0.175 0.0301 0.0337 202.2 5.06 40

0.200 0.0344 0.0331 198.6 5.08 39

.225 0.0387 0.0305 183 5.11 35.8

Result

1. Draw a graph of the axial strain (%) vs. deviatory stress. From this graph, obtain the

value of at failure ( = f)

2. The minor principal stress on the specimen at failure is 3 (i.e. the chamber confining

pressure). Calculate the major principal stress at failure as

31

3. Draw a Mohr’s circle with 1 and 3 as the major and minor principal stresses. The radius

of the Mohr’s circle is equal to Su.

Triaxial Test


Axial Strain vs Stress

0

5

10

15

20

25

30

35

40

45

0 0.01 0.02 0.03 0.04 0.05

Axial Strain (in/in)

Str

ess (

lb/i

n2)

Triaxial Test



UNCONSOLIDATED UNDRAINED TRIAXIAL TEST

(Preliminary data)

Sample No.

Project No.

Boring No.

Location

Depth of sample


Tested by

Date

Moist unit weight of specimen (beginning of test)

Moisture content (end of test)

Dry unit weight of specimen

Initial average length of specimen, Lo cm

Initial average diameter of specimen, Do cm

Initial area, Ao cm2

Gs

Final degree of saturation %

Cell confining pressure, σ3

Proving ring calibration factor

Triaxial Test



UNCONSOLIDATED-UNDRAINED TRIAXIAL TEST

(Axial stress – strain calculation)

Cell confining pressure,σ3=

Specimen

deformation

= δL

(in)

(1)

Vertical

strain,

є = δL

L

(2)

Proving ring

dial reading

(3)

Piston Load,

col.3 x c.f

(calibration

factor)

(lb)

(4)

Corrected

area =

Ac = Ao /1 – є

(in2)

(5)

Deviatory

Stress

Δσ = P/A

(lb/in2)

(6)

Plate Load Test


9 PLATE LOAD TEST

Plate Load Test



1. The test results reflect only the character of the soil located within a depth less than twice

the width of the bearing plate (corresponding to an isobar of one-tenth the loading

intensity at the test plate). Since the foundations are generally large, the settlement and

resistance against shear will depend on the properties of a much thicker stratum.

2. It is essentially a short duration test, and hence the test does not give the ultimate

settlement, particularly in the case of cohesive soils.

3. Another limitation is the effect of the size of foundation. For clay soils the ultimate

pressure for a large foundation is the same as that for the test plate. But in dense sandy

soils, the bearing capacity increases, with the size the foundation, and the test on smaller

size bearing plates tend to given conservative values.

EEFFFFEECCTT OOFF TTHHEE SSIIZZEE OOFF PPLLAATTEE OONN BBEEAARRIINNGG CCAAPPAACCIITTYY

As stated in limitation 3 above, the bearing capacity of sands and gravels increase with the

size of the footing. The relationship can be expressed as under

p

f

fB

BNMq

In the above relation, M term includes the NC and Nq terms while N include N portion of

the bearing capacity equation. The above equation can also be solved graphically by using

more than one size plates

EEFFFFEECCTT OOFF SSIIZZEE OOFF PPLLAATTEE OONN SSEETTTTLLEEMMEENNTT

The settlement of a footing varies with its size. Terzaghi and peck have suggested the

following relationship b/w the settlement of plate (sp) and settlement of actual footing (sf) for

granular soils. 2

fp)3.0Bp(B

)3.0B(BpsS

If s is the permissible settlement of the foundation, the maximum settlement of the largest

forting should be restricted to 4/3s. The corresponding settlement of the test plate (Sp) on

sand, soil is given by 2

p)3.0Bp(B

)3.0B(Bps.

3

4S

DDEETTEERRMMIINNAATTIIOONN OOFF BBEEAARRIINNGG CCAAPPAACCIITTYY

By extrapolating the plate load test data, one can use the following equation for all practical

purposes to determine the bearing capacity of soil.

Plate Load Test


p

fpf

B

Bqq

Where

qf = bearing capacity of the actual footing

Bf = width of actual footing

qp = bearing capacity, obtained from the plate load test

Bp = width of plate

However, for clays, the bearing capacity is almost independent of the footing

size or the plate size.

qf = qb

For a c- soil, housel (1992) suggested the following expression:

Q = A q + P. S

Where

Q = total load on bearing area

A = contact area of footing or plate

P = perimeter of footing

q = bearing pressure beneath area A

S = perimeter shear

DDEETTEERRMMIINNAATTIIOONN OOFF SSEETTTTLLEEMMEENNTT

Settlement of prototype foundation can be estimated from the results of plate load test using

following equations, after Terzaghi (1948).

p

fpf

B

BSS

For clays and if the sand is like an elastic material, then the settlement can be calculated from

p

2

papp IE

u1BS

Where

Sp = plate settlement

ap = applied stress

Bp = width or diameter of the of the plate

u = poisons ratio

E = elastic modulus

Ip = influence factor (0.82 for rigid plate)

The settlement of the real footing of width B is related to the plate settlement

by

Plate Load Test


or 2

pf

2

ppf

3.0B

B2SS

BB

B2SS

for sands

Where

Sf =

settlement of a prototype foundation

Sp = settlement of square plate of 0.3 m by 0.3 m

Bf = width of prototype foundation

Bp = width of the plate

Bond (1961) has proposed the following equation for settlements 1n

f

p

Bp

B

S

S

Where

n = coefficient depending on the types of soil

The value of index n can be determined by carrying out two or more plate

load tests on different size plates. In absence of test data the following values

of n can be adopted:

Clay: 0.03 to 0.05

Sandy clay: 0.0.8 to 0.10

Dense sand: 0.4 to 0.5

Medium to dense sand: 0.25 to 0.35

Loose sand: 0.20 to 0.25


DDEEFFLLEECCTTIIOONN

The amount of downward vertical movement of a surface due to the application of a load to

the surface.

RREESSIIDDUUAALL DDEEFFLLEECCTTIIOONN

The difference between original and final elevations of a surface resulting from the

application and removal of one or more loads to and from the surface.

RREEBBOOUUNNDD DDEEFFLLEECCTTIIOONN

The amount of vertical rebound of a surface that occurs when a load is removed from the

surface.

Plate Load Test


BBEEAARRIINNGG CCAAPPAACCIITTYY

The pressure that a soil sample can sustain without failing is called the bearing capacity of

soil.

SSOOIILL SSEETTTTLLEEMMEENNTT

The process of compression (reduction in the volume of voids) of soil due to the expulsion of

air, water or both from the voids as a result of increased loading (such as geostatic weight or

weight of structure above) is called soil settlement.


This experiment is used to determine the ultimate and or safe bearing capacity of the full-

scale foundation.


This method covers the making of non repetitive static plate load test on subgrade soils and

flexible pavement components, in either the compacted condition or the natural state, and is

intended to provide data for use in the evaluation and design of rigid and flexible type

airport and highway pavements.


ASTM: D1194

AASHTO T 222-81


99..55..11 FFIIEELLDD TTEESSTT AAPPPPAARRAATTUUSS

The required field test apparatus is as follows

1. Load reaction equipment. Load reaction equipment consisting of a truck, trailer,

anchored frame, or similar device having a dead load of at least 25,000 lb.

2. Bearing plates. Bearing plates consisting of a 30-in., 24-in., and 18-in.-diameter steel

plate, each plate 1 in. thick. Aluminum alloy No. 24ST plates 1.5 in. thick may be

used in lieu of steel plates.

3. Jack. Hydraulic jack capable of applying loads of at least 25,000 lb.

4. Ball joint. A ball joint to be inserted between the jack and load reaction equipment or

between the jack and bearing plates to prevent eccentricity of loading.

Plate Load Test


5. Load-measuring device. A load-measuring device consisting of either a hydraulic

gage on the jack, a steel proving ring, or load cell. All are satisfactory for measuring

applied load, but must be accurately calibrated.

6. Micrometers. Three dial micrometers, reading to 1/10,000 in., dial stems, and support.

7. Sand/plaster of Paris. Clean sand or plaster of Paris.

8. Cribbing. Cribbing of short pieces of hardwood or steel H- or I-beams.

9. Stopwatch.

10. Containers. Containers for undisturbed soil samples.

11. Consolidometer apparatus.

12. Cutting equipment. Necessary equipment for cutting an undisturbed specimen of the

soil into a consolidometer test ring.

13. Scales

14. Oven

15. Miscellaneous tools for making moisture-content determinations.

Figure 9.1 Plate load test apparatus

Plate Load Test



The test pit width is made five times the width of the plate Bp. At the center of the pit, a

small square hole is dug whose size is equal to the size of the plate and the bottom level of

which corresponding to the level of the actual foundation (figure) the depth Dp of the hole

should be such that the loading to the plate may be applied with the help of a hydraulic jack.

The reaching of the hydraulic jack may be borne by either of the following two methods

a) Gravity loading plate form method

b) Reaction truss method

In the case of gravity loading method, plate form is constructed over a vertical column

resting on the rest plate, and the loading is done with the help of sand bags, stone or concrete

blocks. The general arrangement of the test set-up for this method is shown in the figure.

When load is applied to the plate, it sinks or settles. The settlement of the plate is measured

with the help of sensitive dial gauge. For square plate, two dial gauges are used. The dial

Figure 9.2 Schematic diagram of Plate load test

Bp

5Bp

Dp

D

Bearing Plate Foundation level

Hydraulic jack

Plate form Main girder

Sand bags

Datum bar Dial gauges

Test plate

Masonry support

Loading post

Plate Load Test


gauges are mounted on independently supported datum bar. As the plate settles, the ram of

the dial gauge moves down and settlement is recorded. The load is indicated on the load-

gauge of the hydraulic gauge of the hydraulic jack.

The load is applied with the help of a hydraulic jack (preferably with the remote control

pumping unit), in convenient increments, say of about one-fifth of the expected safe bearing

capacity or one-tenth of the ultimate bearing capacity. Dial gauges fixed at diametrically

opposite ends, with sensitivity of 0.02mm, observe settlement of the plate.

Settlement should be observed for each increment of load after an interval of 1,4,10, 20, 40

and 60 minutes and thereafter at hourly interval until the rate of settlement becomes less than

about 0.02mm per hour. After this, the next load increment is applied. The maximum load

that is to be applied corresponds to 3 time’s proposed allowable bearing pressure.

The water table has a marked influence on the bearing capacity of sand or gravelly soil. If the

water table is already above the level of the footing, it should be lowered by pumping and the

bearing plate seated after the water table has been lowered just below the footing level. Even

Figure 9.3 Schematic diagram of Plate load test

Bp

5Bp

Dp

D

Bearing Plate Foundation level

Hydraulic jack

Plate form Main girder

Sand bags

Datum bar Dial gauges

Test plate

Masonry support

Loading post

Plate Load Test


if the water table is locate above 1 m below the base level of the footing, the load test should

be made at the level of the water table itself.

When a load settlement curve (Fig 9.2) does not indicate any marked breaking point, failure

may alternatively be assumed corresponding to settlement equal to one fifth of the width of

the test plate. In order to determine the safe bearing capacity it would be normally sufficient

to use a factor of safety of 2 or 2.5 on ultimate bearing capacity.

Chart 9.1 Load vs. Settlement


1. The Plate Bearing (or Loading) Test, is normally used to measure the short term

settlement of road sub-grade or building footings under their proposed design load.

The value of settlement against load is then used to check that the soil meets design

load settlement criteria. The test therefore is of use to both contractors and to

specifying authorities.

2. In addition to values of settlement, other soil parameters can be measured, or

calculated from the plate bearing test. These include Modulus of Sub-Grade Reaction,

permanent deformation characteristics of the soil and in some instances shear strength

of the soil.

3. This method of testing is used for determining the modulus of reaction of soils by

means of the plate bearing test and for determining the corrections to be applied to the

0

4

8

12

16

20

24

28

32

0 1 2 3 4 5 6 7 8 9 10

Set

tlem

ent

(mm

)

Load kg/cm square

Plate load data

Plate Load Test


field test values by means of laboratory tests. The modulus of soil reaction is required

in rigid pavement design and evaluation.

4. This test method is used to estimate the bearing capacity of a soil under field loading

conditions for a specific loading plate and depth of embedment but also for load tests

of soil and flexible pavement components for use in evaluation and design of airport

and highway pavements.

99 .. 88 PP RR EE CC AA UU TT II OO NN SS

1. Sample should make with care.

2. Apparatus should be handled carefully.

California Bearing Ratio Test


10 CALIFORNIA

BEARING RATIO

TEST



11 00 .. 11 II NN TT RR OO DD UU CC TT II OO NN

The CBR test was developed by California Division of Highway in 1929 as mean of classify

the suitability of a soil for use as a sub grade or base course material in highway construction.

The laboratory test measures the shearing resistance of a soil under controlled moisture and

density conditions.


CCAALLIIFFOORRNNIIAA BBEEAARRIINNGG RRAATTIIOO

The CBR for a soil is the ratio (expressed as %) obtained by dividing the penetration stress

required to cause a 3-in2

area (hence, a 1.95-in. diameter) piston to penetrate 0.10 in. into the

soil by a standard penetration stress of 1,000 psi.

It may be expressed in the equation form as

1001000

).10.0(..).(.

psi

inchespenetratetorequiredpsistressnpenetratioCBR

Note: The 1,000 psi in the denominator is the standard penetration stress for 0.10 in.

penetration.

SSUUBB GGRRAADDEE

The natural soil upon which the pavement is laid. The sub grade is seldom strong enough to

carry a wheel load directly.

11 00 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT

This method describes the sampling of the sub grade for California Bearing Ratio

(CBR)The resulting information is used for pavement design thickness.

11 00 .. 33 SS CC OO PP EE OO FF TT EE SS TT

This test method is used to determine layer thicknesses and in-place California Bearing Ratio

(CBR) and to obtain samples of the pavement layer, base, sub-base, and sub-grade for

laboratory testing. The test method is applicable to both asphalt concrete (AC) and Portland-

cement concrete (PCC) pavements.

The strength of the sub grade is the main factor in determining the thickness of the pavement

although its susceptibility to frost must also be considered. The value of the stiffness of the

sub grade is required if the stresses and strains in the pavement and the sub grade are to be

calculated.



11 00 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE

ASTM D1883-73

11 00 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT

1. CBR test apparatus: Compaction mold (6-in. diameter and 7-in. height),collar, spacer

disk ( 5.937 diameter and 2.416-in. height),adjustable stem and perforated plate,

weights, penetration piston(3 in² in area)

2. Loading (compression) machine: with load capacity of at least 10,000 lb and

penetration rate of 0.05 in./min

3. Expansion measuring apparatus

4. Two dial gages (with accuracy to 0.001 in.)

5. Standard compaction hammer

6. Mixing bowl

7. Scales

8. Soaking tank

9. Oven

Figure 10.1 CBR test apparatus



11 00 .. 66 TT EE SS TT PP RR OO CC EE DD UU RR EE

1. Place the mould with base plate containing the sample, with the top face of the

sample exposed, centrally on the lower platen of the testing machine.

2. Place the appropriate annular surcharge discs on top of the sample.

3. Fir into place the cylindrical plunger and force-measuring devise assembly with the

face of the plunger resting on the surface of the sample.

4. Apply a seating force to the plunger, depending on the expected CBR value, as

follows.

5. for CBR value up to 5%, apply 10 N

6. for CBR value from 5% to 30%, apply 50 N

7. for CBR value above 30%, apply 250 N

8. Secure the penetration dial gauge in position. Record its initial zero reading, or reset it

to read zero.

9. Start the test so that the plunger penetrates the sample at a uniform rate of

10.2mm/min, and at the same instant start the timer.

10. Record readings of the force gauge at intervals of penetration of 0.25mm, to a total

penetration not exceeding 7.5mm

11. After completing the penetration test or tests, determine the moisture content of the

test sample

12. Test results are plotted in the form of a load-penetration diagram by drawing a curve

through the experimental points. Usually the curve will be convex upwards but

sometimes the initial part of the curve is concave upwards and, over this section, a

correction becomes necessary. The correction consists of drawing a tangent to the

curve at its steepest slope and producing it back to cut the penetration axis. This point

is regarded as the origin of the penetration scale for the corrected curve.

13. Penetrations of 2.5mm and 5mm are used for calculating the CBR value. From the

test curve, with corrected penetration scale if appropriate, read off the forces

corresponding to 2.5mm and 5mm penetration. Express these as a percentage of the

standard forces at these penetrations. Take the higher percentage as the CBR value.

11 00 .. 77 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS

This test method is used to evaluate the potential strength of sub grade, sub base, and base

coarse material including recycled materials for use in road and airfield pavements. The CBR

value obtained in this test forms an integral part of several flexible pavement design methods.

For applications where the effect of compaction water content on CBR is unknown or where

it is desired to account for its effect, the CBR is determined for a range of water content,

usually the range of water content permitted for field compaction by using agency’s field

compaction specification.



11 00 .. 88 PP RR EE CC AA UU TT II OO NN SS

1. Scale must be precise.

2. Width of groove must be accurate.

3. Depth of groove must be accurate.

4. Handle of turning pace should be done with care.

11 00 .. 99 CC AA LL CC UU LL AA TT II OO NN SS

CBR value for 2.5mm (0.1in) penetration

( ) ( )

( ) ( )

CBR value for 5.0mm (0.2in) penetration

( ) ( )

( ) ( )

11 00 .. 11 00 CC OO RR RR EE CC TT II OO NN SS TT OO CC UU RR VV EE

The correction to the curve and reading given on the next page should be done.



11 00 .. 11 11 SS AA MM PP LL EE PP RR OO BB LL EE MM


CALIFORNIA BEARING RATIO TEST

Moisture Content Determination

Before

compaction

after

compaction

Top 1 in layer

after soaking

Average moisture

content after

soaking

can no. 1-A 1-B 1-C 1-D

weight of can, W1 (g) 45.23 47.28 43.44 46.59

weight of can + wet soil, W2 (g) 315.94 326.01 304.71 356.37

weight of can + dry soil, W3 (g) 273.69 283.37 261.53 305.82

mc (%)=(W2-W3)/(W3-W1)×100 18.49 18.06 19.79 19.50

Average moisture content before soaking (%) = 18.27

Average moisture content after soaking (%) = 19.64

Density Determination

Before soaking After soaking

weight of mold + compacted soil specimen (g) 9020.9 9036.81

Weight of mold (g) 4167.5 4167.5

Weight of compacted soil specimen (g) 4853.4 4869.31

Diameter of mold (in.) 6 6

Area of soil specimen (in2) 28.278 28.278

height of soil specimen (in.) 5 5

Volume of soil specimen (in.3) 141.39 141.39

Wet density (lb/ft3) 130.76 131.19

Moisture content (%) 18.27 19.64

Dry density (lb/ft3) 110.56 109.64



Swell Data

Initial swell

measurement

Final swell

measurement

Surcharge weight (lb) 10 10

Time 10:16 AM 10:16 AM

Date 5/26/2006 5/30/2006

Elapsed time (hr) 0 96

Dial reading(in.) 0 0.0135

Initial height of soil specimen (in.) 5 5

Swell (% of initial height) 0 0.27

Bearing Ratio Data

Check one soaked unsoaked

Weight of surcharge (lb) 10

Proving ring calibration (lb/in) 74000

Penetration

(in)

Proving ring dial

reading (in.) Piston load (lb)

Area of piston

(in.2)

penetration stress

(psi)

1 2 3=2×proving ring

calibration 4 5=3/4

0 0 0 3 0

0.025 0.0004 29.6 3 9.86

0.05 0.0008 59.2 3 19.73

0.075 0.0013 96.2 3 32.06

0.1 0.0016 118.4 3 39.46

0.125 0.0019 140.6 3 46.86

0.15 0.002 148 3 49.33

0.175 0.0022 162.8 3 54.26

0.2 0.0023 170.2 3 56.73

0.3 0.0026 192.4 3 64.13

0.4 0.003 222 3 74

0.5 0.0032 236.8 3 78.93

Result

CBR at 0.10-in. penetration (%) = [corrected penetration stress for 0.10 in penetration (from curve of

penetration stress versus penetration)]/1000×100 = 3.95


penetration stress versus penetration)]/1500×100= 3.78



Curve of Penetration Stress vs Penetration

0

10

20

30

40

50

60

70

80

90

0 0.1 0.2 0.3 0.4 0.5 0.6

Penetration (in.)

Pe

ne

tra

tio

n s

tre

ss

(p

si)




CALIFORNIA BEARING RATIO TEST

Moisture Content Determination

Before

compaction

after

compaction

Top 1 in layer

after soaking

Average moisture

content after soaking

can no.

weight of can, W1 (g)

weight of can + wet soil, W2 (g)

weight of can + dry soil, W3 (g)

mc (%)=(W2-W3)/(W3-W1)×100

Average moisture content before soaking (%) =

Average moisture content after soaking (%) =

Density Determination

Before soaking After soaking

weight of mold + compacted soil specimen (g)

Weight of mold (g)

Weight of compacted soil specimen (g)

Diameter of mold (in.)

Area of soil specimen (in2)

height of soil specimen (in.)

Volume of soil specimen (in.3)

Wet density (lb/ft3)

Moisture content (%)

Dry density (lb/ft3)



Swell Data

Initial swell

measurement Final swell measurement

Surcharge weight (lb)

Time

Date

Elapsed time (hr)

Dial reading(in.)

Initial height of soil specimen (in.)

Swell (% of initial height)

Bearing Ratio Data

Check one soaked unsoaked

Weight of surcharge (lb)

Proving ring calibration (lb/in)

Penetration (in) Proving ring dial

reading (in.) Piston load (lb)

Area of piston

(in.2)

penetration

stress (psi)

1 2 3=2×proving ring

calibration 4 5=3/4



Result CBR at 0.10-in. penetration (%) = [corrected penetration stress for 0.10 in penetration (from curve of

penetration stress versus penetration)]/1000×100 =


penetration stress versus penetration)]/1500×100=

Bibliography


BIBLIOGRAPHY

Bibliography


BB II BB LL II OO GG RR AA PP HH YY

Braja M. Das, Soil Mechanics Lab Manual,

Arpad Kezdi, Hand Book of Soil Mechanics and Soil Testing,

K. H. Head, Manual of Soil Laboratory Testing,

Joseph E. Bowles, Engineering Properties of Soil and Their Measurements, fourth edition,

BS 1377: Part 2 (1990), British Standard Methods of Test for Soil for Engineering Purposes.

Cheng Liu, Jack B. Evett, Soil Properties (Testing, Measurement and Evaluation), second

edition,

W. L. Schroeder, Soil in Construction (fifth edition),

ASTM 1988 ‘Annual book of ASTM Standards’

Book of Standards Volume: 04, Publisher: Taylor & Francis, Volume 22, Number 7 / 2004

Ashworth Manual, Embankment and Bas’,

Prof. Krishna Reddy, UIC, Engineering Properties of Soils Based on Laboratory Testing

Soil mechanics work book

Dr. J. T. Germaine, Civil engineering material laboratory

Bardet, Jean-Pierre. (1997), Experimental Soil Mechanics. Prentice-Hall,

Means, R.E. and Parcher, J.V. (1963), Physical Properties of Soils

Ajay K. Duggal and Vijay P. Puri, Laboratory Manual in Highway Engineering,

H. S. Moondra, Rajiv Gupta, Lab Manual for Civil Engineering,

http://www.vulcanhammer.net “Laboratory Soils Testing”

http://www.mastrad.com/speed.htm

http://www.geneq.com/catalog/en/large_speedy.html

http://www.mbt.co.id/equipment/so-430.html

Bibliography


http://www.humboldtmfg.com/c-5-p-222-id-5.html

http://www.aimil.com/Search/ProductDetails.aspx?Id=913

http://www.udot.utah.gov/dl.php/tid

http://www.sddot.com/pe/materials/docs/matlsman/sd

http://www.civl.port.ac.uk/projects/geotech/geo4.html

http://geotech.uta.edu/lab/Main/atrbrg_lmts/index.htm

http://www.astm.org/cgi-bin/softcart.exe/database.cart/redline_pages/d4318.htm?e+mystore

http://www.civl.port.ac.uk/projects/geotech/geo5.html

http://www.stl-inc.com

http://www.atechcenter.com/hyd1.html

http://www.uwe.ac.uk/geocal

http://www.webstore.ansi.org

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