proba mackintosh.docx

INTRODUCTION

A through soil investigation is required before a construction project begins. This is important to assure the safety of the construction, the residence and the surroundings. The main reason for a soil investigation is to identify the type of soil for each soil layer underneath the foundation of the construction to be built, soil strength and moisture content of the soil. There are various types of soil investigation methods that are conducted on construction sites or in the civil engineering laboratories. There are determination of soil bearing capacity and moisture content. Soil bearing capacity is the ability of soil to support weight from the foundation of a structure is known as the bearing capacity of soil. The test used to determine bearing capacity of soil is Mackintosh Probe Test.

Dynamics probe test

Cone penetration testTo carried out the cone penetration test is pushed into a soil deposit while various measured parameters are recorded. The test is similar to the dutch deep sounding (or piezocone test) with the addition of a cone penetration element in the probe to measure water pressure. The test is also known as pore pressure sounding.

Mackintosh/JKR probe testThis is a dynamic penetrometer test used to check the consistency of the subsoil. Mackintosh probe which has 30° cone penetrometer while JKR probes has 60° cone penetrometer. This is a light dynamic test and the cone is driven directly into the soil by driving a hammer 5 kg. Weight dropping through a free height of 280mm. The probe is unable to penetrate into medium strength soil and gravelly ground.

BoreholesA borehole is used to determine the nature of the ground (usually below 6m depth) in a qualitative manner and then recover undisturbed samples for quantitative examination. Where this is not possible, for in gravelly soils below the water table, in-situ testing methods are used. Obviously the information gained from a borehole is an extremely limited picture of the subsurface structure. It is there fore essential to compare the results obtained with those that could have been expected from the desk study. The greater number of boreholes the more certain it is possible to be of the correlation and thus to trust in the results.

Hand augerA large (4m x 4m x 7m high) percussion rig that drives a cutting or collecting instrument (dependent on ground conditions) into the ground, to collect soil that is then removed and sampled. This can be a slow technique however the advantage is that the hole can be cased to prevent collapse in loose soil layers, allowing easy installation of groundwater sampling pipe work. It is highly adaptable to, and designed for, geotechnical testing.

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OBJECTIVE

1. Collecting a disturbed soil sample for grain-size analysis and soil classification2. Determine sub-surface stratgraphy and identity materials present3. Evaluate soil density and in-situ stress conditions4. Estimate geotechnical parameters

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THEORY

The main purpose of the test is to provide an indication of the relative density of granular deposit, such as sands and gravels from which it is virtually impossible to obtain undisturbed samples. The great merit of the test and the main reason for its widespread use is that it is simple and inexpensive. The soil strength parameters which can be inferred are approximate, but may give a useful guide in ground conditions where it may not be possible to obtain borehole samples of adequate quality like gravels, sands, silts, clay containing sand or gravel and weak rock.

The usefulness of SPT results depends on the soil type, with fine-grained sands giving the most useful results, with coarser sands and silty sands giving reasonably useful results, and clay and gravelly soils yielding results which may be very poorly representative of the true soil conditions.

This test method provides a disturbed soil sample for moisture content determination, for identification and classification purposes, and for laboratory tests appropriate for soil obtained from a sampler that will produce a large shear strain disturbance in the sample. Soil deposits contained gravels, cobbles or boulders typically result in penetration refusal and damage to equipment.

This test method is used extensively in a great variety of geotechnical exploration projects. Many local correlations and widely published correlation which relate blow count, or N-value, and the engineering behave of earthworks and foundations are available.

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APPARATUS

1. Boring Rods

2. Rod Couplings

3. Lifting tools

4. Penetration Cone

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5. Hammer

6. Wrench

7. Ruler

8. Marking tools

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PROCEDURE

1. Equipments for the test are assembled. The cone diameter is measured in SI unit.

2. The boring rods and hammer are joint using the rod coupling. Grease is sweep up for an easy dissembles later.

3. Distance of 0.3 m is measured and marked on the rod start from the tip of the cone.

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4. The equipment is set up on the ground.

5. The hammer is pulled until it reached the maximum. The hammer is dropped freely to driven the cone into the soils.

6. The sum of the number of blows for penetration of 0.3 m is recorded in the data sheet.

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7. The hammer is taken off on the last 0.3 m of each rod and joined the existing rod with another rod and lastly the hammer. The blow is continued and stopped when:

• The blow is more than 400 for 0.3 m penetration• The depth reached 15 m

8. Pull the rods using lifting tools after the penetration reached the requirement.

9. The equipment is dissembled and cleaned before storing.

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Depth(m)Point no.: 01Date: 30/12/2012Number of stamped/0.3m

cumulative number stamped

0.0-0.3 122 122

0.3-0.6 70 192

0.6-0.9 298 490

0.9-1.2 347 837

1.2-1.5 105 942

1.5-1.8 115 1057

1.8-2.1 133 1190

2.1-2.4 97 1287

2.4-2.7 88 1375

2.7-3.0 257 1632

3.0-3.3 400 2032

RESULT 01

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CALCULATION 01

Depth

A

First layer

B

Second layer

C

Third layer

D

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Number of stamp from BC = =

Total interval from b to c =

Number shock / 0.3m ==

The value of the bearing capacity of the bearing capacity versus number of graphs shock =



0.0-0.3 105 105

0.3-0.6 244 349

0.6-0.9 222 571

0.9-1.2 176 747

1.2-1.5 61 808

1.5-1.8 71 879

1.8-2.1 129 1008

2.1-2.4 128 1136

2.4-2.7 151 1287

2.7-3.0 180 1467

3.0-3.3 400 1867

RESULT 02

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CALCULATION 02

Depth

A

First layer

B

Second layer

C

Third layer

D

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Number shock / 0.3m = =




0.0-0.3 131 131

0.3-0.6 79 210

0.6-0.9 132 342

0.9-1.2 182 524

1.2-1.5 201 725

1.5-1.8 88 813

1.8-2.1 327 1140

2.1-2.4 114 1254

2.4-2.7 119 1373

2.7-3.0 119 1492

3.0-3.3 341 1833

3.3-3.6 400 2233

RESULT 03

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CALCULATION 03

Depth

A

First layer

B

Second layer

C

Third layer

D

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0.0-0.3 125 125

0.3-0.6 82 207

0.6-0.9 135 342

0.9-1.2 200 542

1.2-1.5 90 632

1.5-1.8 100 732

1.8-2.1 333 1065

2.1-2.4 89 1145

2.4-2.7 109 1263

2.7-3.0 252 1515

3.0-3.3 352 1867

3.3-3.6 370 2237

3.6-3.9 400 2637

RESULT 04

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CALCULATION 04

Depth

A

First layer

B

Second layer

C

Third layer

D

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DISCUSSION

1. The test is carried out first before the tests other sites before a construction project initiated to ensure the land in accordance with the construction project or not. In addition, the small size and lightweight device that causes the work easy to handle and quick.

2. ADVANTAGES The size of a small, lightweight device causing easily handled and

speed work Tests performed earlier than tests of other sites before a project

underway Information and data were obtained more quickly, easily and save time The cost of handling, equipment and the use of relatively cheap

DISADVANTAGES Use limited in terms of the impact energy is too limited Bearing capacity of soil foundation design is a development known only

superficial.

3. The probe testing hole to ensure the project is determined on-site project is located right in the building. Also, make sure that the test holes are free of tree roots that can prevent devices from getting into the ground.

4. The way to stamp the weight member to the weight and pressure will affect the number of entries into the ground rod. In addition, the possibility to be bent rod may also occur due to excessive load during stamping. Number of shock should also be the same as during the test run and the counter weight should also be taken at the proper height.

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CONCLUSION

When we do this experiment, we managed to complete in 2 hour. When the experiment is conducted, we learn how the probe mackintosh is conduct when the penetration of the boring rod penetrate to the ground. There were 4 boring rod used in this experiment. This experiment is conducted similar to piling work at construction site.

We get the data and tabulate it into form. From that we learn how to calculate the data that we got. After the calculation is done, we plotted the graph from the calculation.

Probe has a knocker that will be passed to suppress the cone into the soil to be tested. Total amount of knock every one foot or 300mm will be recorded. Into the test is limited to a maximum of 60 feet.

Test results interpreted in the form of soil bearing strength. This value can be used in basic research as well as building other studies on soil strength. Probe is also often used to complement the data about the strength of the soil layer between the bore holes. This test is usually carried out at a distance of 30-50 feet.

Interpretation of the bearing strength is made using a specified formula or using the graph.

• If the value of knocking on 10, meaning very poor soil.• if knock between 10 to 40, sediment testing needs to be done.• Knocking over 40 marked the land is quite strong for the base building or

other structure.

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proba mackintosh.docx

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