# soil mechanic

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Lectures, exercise and some answer for practicing. Mr SEANG POV is one of best professor in soil mechanic in cambodia

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• Advance Soil mechanics Present by Mr. Sieng PEOU

Master science of geotechnical engineering

• Soils particle size

19.5mm>d>4.76mm.

Gravel

4.76mm>d>0.075mm

Sand

Coarse grained soils

0.075mm>d>0.002mm

Silt

d

• Sieve analysis method

For coarse grained soils

• Retained cumulative

%R= %100

.

..

weighttotal

cumulativeretainedweight

Passing cumulative

%P = 100-%R

• Logarithm scale

Logd

0.001 0.01 0.1 1 10 100

a

If 0.001

• Hydrometer analysis

For fine grained soils

• Hydrometer analysis

%100*%SW

RRaP +=

TLKD =

P%-passing cumulative

a- soil factor

R-corrected factor

Ws-weight of dry soil

D-soil diameter

K-hydrometer factor

L-depth of hydrometer in

Solution

time in minute

• Soil particle size curve Uniformity coefficient UC=D60/D10

d10 d60

• Weight and volume relation ship

V

Va

Vw

Vs

W

Wa=0

Ww

Ws

• W=Ws+Ww

V=Va+Vw+Vs

Vv =Va+Vw

V= Vv+Vs

• Soils sampling Disturbed sample for determine properties

physics of soils Undisturbed sample for determine

properties mechanics of soils, we call undisturbed when AR(%)

• Soils unit weight Natural water content:

Bulk unit weight:=

Dry unit weight: d=

Unit weight of particle solid: s=

ws

e

eSGVW

+

+=

1

s

s

VW

1001

+

=

VW s

%100=s

w

WW

• Another parameter Void ratio:

Degree of saturation:

Saturated unit weight:

Effective unit weight:

d

ds

s

v

VV

e

==

w

s

v

w

eVVS

== %100

Ws

sate

eG

+

+=

1

ws

wsate

G

+

==

11

'

• Another parameters Specific gravity:

Relative density:

Saturated water content:

ws

ss V

WG

=

%100minmax

max

=

ee

eeDR

%10011

= w

sdsat

• Typical values of unit weight of soils

Soil type sat(KN/M3) d(KN/M3)

Gravel 20 to 22 15 to 17

Sand 18 to 20 13 to 16

Silt 18 to 20 14 to 18

Clay 16 to 22 14 to 21

• Description based on Relative density

DR(%) Description 0 to 15 Very loose 15 to 35 Loose

35 to 65 Medium dense 65 to 85 Dense

85 to 100 Very dense

• Soil consistence

ShrinkagelimitWs

PlasticlimitWp

LiquidlimitWL

Atterberglimit

• State of cohesion soils Plastic index IP=WL-WP

Liquidity index IL=

P

P

I

• State of cohesion soils

If 0

• CH

MH CL

ML

CL-ML

• Soil classification USCS:Unified soil classification system

(ASTM Test Designation D-2487) ASTM: American Society for Testing and Materials Proposed by Casagrande in 1942,this system was revised in 1952 by U.S Bureau of Reclamation.

• Coarse grained soils

%R(4.76mm)>0.5%R(0.075mm)Gravel

%R(4.76mm)50%Coarse grained soils

• Gravel

GW

Clean Gravel%P(0.075mm)

• Gravel

Located CL or CHPoorly gradedclayey Gravel

GC-GP

Located ML or MHPoorly graded silty Gravel

GM-GP

silty GravelGC-GM-GP

UC4On plastic Chart Casagrande

Mixed Gravel5%

• Gravel

Located CL or CHclayey Gravel

GC

Located ML or MH silty Gravel

GM

Located CL-ML clayey silty Gravel

GC-GM

Mixed Gravel%P(0.075mm)>12%

• Sand

SW

Clean Sand%P(0.075mm)

• Sand

Located CL or CHPoorly gradedclayey Sand

SC-SP

silty SandSM-SP

silty SandSC-SM-SP

UC6On plastic Chart Casagrande

Mixed Sand5%

• Sand

Located CL or CHclayey Sand

SC

Located ML or MH silty Sand

SM

Located CL-ML clayey silty Sand

SC-SM

Mixed Sand%P(0.075mm)>12%

• Fine grained soils

CL CH

For Clay

ML MH

For Silt

CL-ML

For Silty clay

%R(0.075mm)

• Lean Clay(CL)

%S>%GLean ClayWith sand

%S

• Fat Clay(CH)

%S>%GFat Clay

With sand

%S

• Silt (ML)

%S>%GSilt

With sand

%S

• Elastic Silt (MH)

%S>%GElastic SiltWith sand

%S

• Silty clay (CL-ML)

%S>%GSilty clay

With sand

%S

• Soil classification AASHTO:Association American for

State Highway and Transportation official, was developed 1929 and proposed by the committee on Materials for sub grades and Granularity Type Boards of the Highway Research Road in 1945(ASTM Test designation D-3282;AASHTO method M145)

• Granular Materials %P(0.075mm)
• Silty - clay material %P(0.075mm)>35% Group classification A-4 A-5

A-6

A-7 A-7-5 A-7-6

%P(2mm) %P(0.425mm) %P(0.075mm) >35% >35% >35%

>35%

WL 40 40 IP 10 Usual type of materials

Silty soils Clayey soils

Fair to poor

For A-7-5: IPWL-30

• Group index GI

GI=(%P(0.075)-35)[0.2+0.005(WL-40)]+0.01(%P(0.075)-15)(IP-10)

• Soil compaction Standard Proctor test

Modified Proctor test

• Specification for standard Proctor test(based on ASTM test designation 698-91)

Item Method A Method B Method C Diameter of mold 101.6mm 101.6mm 152.4mm

Volume of mold 943.3cm3 943.3cm3 2124cm3 Weight of hammer 24.4 N 24.4 N 24.4 N Height of hammer drop 304.8mm 304.8mm 304.8mm Number of hammer blows per layer

25 25 56

Number of layer of compaction

3 3 3

Energy of compaction 591.3KNm/m3 591.3KNm/m3 591.3KNm/m3 Soil to be used %R(4.75)20% %R(9.5)20% %R(19)

• Specification for modified Proctor test(based on ASTM test designation 1557-91)

Item Method A Method B Method C Diameter of mold 101.6mm 101.6mm 152.4mm

Volume of mold 943.3cm3 943.3cm3 2124cm3 Weight of hammer 44.5 N 44.5 N 44.5 N Height of hammer drop 457.2mm 457.2mm 457.2mm Number of hammer blows per layer

25 25 56

Number of layer of compaction

5 5 5

Energy of compaction 2696KNm/m3 2696KNm/m3 2696KNm/m3 Soil to be used %R(4.75)20% %R(9.5)20% %R(19)

• Compaction equipment

• Compaction curve MOISTURE DENSITY RELATIONSHIP CURVE

1.900

2.000

2.100

2.200

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

Moisture content %

D

r

y

D

e

n

s

i

t

y

g

/

m

3

Wopt

dmax

• California Bearing Ratio(CBR) For study the strength of soils after

compacting in optimum state. 1-Recompaction the soil in optimum

state 2-Determine CBR in dry condition 3-Saturated the soil under water 4 days 4-Determine CBR in soaked condition CBR=

%100..standard

..

• BEARING RATIO TEST (CBR)

Project: Pochentong Airport Job No.Location of Project: Pochentong Airport Boring No 2 Sample No.2Description of Soil: Tested by: Mr. Men Tharith Date of Testing. 16/05/2002

mm ( unit )0.000 0 01.00 0.045 2.30772.00 0.075 3.84623.00 0.11 5.6414.00 0.145 7.43595.00 0.175 8.97446.00 0.21 10.7697.00 0.25 12.8218.00 0.28 14.3599.00 0.31 15.89710.00 0.34 17.436

CBR(2.54)= 7.1429

Acceppted CBR= 7.14

Final water Top 7.9conten, w% Midle 7.8

(soaked) Bottom 7.99sample Averagee 7.8967

Wet unit wt. = 2.2952 g/cm3 Dry unit wt. = 2.13444 g/cm3

Wet unit wt.(soaked) = 2.303 g/cm3

Curve CBR Test

0

2

4

6

8

10

12

14

16

18

20

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0

Renetration (mm)

L

o

a

d

(

k

g

f

/

c

m

2

)

P2.54

2.5 6.9

5 10.3

7.5 13

10 16

12.7 18

• CBR equipment

• CBR equipment

• CBR special for field control Compaction the soils in optimum state

with different energy 1-Compaction 10 blows per layer and

saturated the soil under water during 4 days

2-Compaction 25 blows per layer and saturated the soil under water during 4 days

3-Compaction 55 blows per layer and saturated the soil under water during 4 days

4-Determine CBR in soaked condition for

• CBR chart

• CBR General rating

Uses Classification system

USCS AASHTO

0-3 Very poor

OH,CH,MH,OL

A5,A6,A7

3-7 Poor to fair

OH,CH,MH,OL

A4,A5,A6,A7

7-20 Fair Subbase OL,CL,ML,SC,SM,SP

A2,A4,A6,A7

20-50 Good Base subbase

GM,GC,SW, SM,SP,GP

A1b,A2-5, A3,A2-6

>50 Excellent