Soil Mechanics II (Geotech Engg) lab Report PDF

Preview

Summary

Geo technical Engineering is the speciality of Civil Engineering which deals with the
property and behaviour of soil and rock in engineering purposes...

Description

Soil Mechanics II (Geotechnical Engineering) Lab Report

CED, UET-P

Muhammad Bilal

GEOTECH-II CE-313L

Group Report

Abstract: Geotechnical Engineering is the specialty of Civil Engineering which deals with the property and behavior of soil and rock in engineering purposes. To obtain different properties of soil, laboratory tests are performed on collected disturbed and undisturbed soil samples, while field tests are performed on sub-soil at in-situ condition following mainly standard ASTM methods. The first step in any geotechnical engineering project is to identify and describe the subsoil condition. For example, as soon as a ground is identified as gravel, engineer can immediately form some ideas on the nature of problems that might be encountered in a tunneling project. In contrast, a soft clay ground is expected to lead to other types of design and construction considerations. Therefore, it is useful to have a systematic procedure for identification of soils even in the planning stages of a project. Soils can be classified into two general categories: (1) coarse grained soils and (2) fine grained soils. Usually coarse-grained soils are sand, gravel, cobble and boulder, while finegrained soils are silt and clay. The following tests was performed by the students of Civil Engineering Department U.E.T Peshawar (the list of experiments can be seen in table of contents) under the supervision of Sir Engr. Zia Ullah. The main purpose of this lab was to investigate different types of soils through different tests and to compare them with the standards mostly ASTM. Soil behaves differently in different conditions. Field identification tests of soil and laboratory tests like direct shear test may be performed on collected disturbed soil samples, unconfined compression test, consolidation test and triaxial test may be performed on collected undisturbed soil samples according to ASTM (American Standards for Testing Materials) methods. This Lab manual was prepared with the help of ASTM and ―Engineering Properties of Soil based on Laboratory Testing.

Civil Department, UET Peshawar

1|Page

GEOTECH-II CE-313L

Group Report

Contents: Experiment 1:

“Direct shear test” .................................................................. 5

Objective: .................................................................................................................................. 5 Need and scope: ........................................................................................................................ 5 Planning and organization: ..................................................................................................... 5 Knowledge of equipment:........................................................................................................ 5 Procedure: ................................................................................................................................ 6 Parts of Apparatus:.................................................................................................................. 7 Data: .......................................................................................................................................... 8 Graphs: .................................................................................................................................. 10 General Remarks: .................................................................................................................. 11

Experiment # 2 ................................................................................... 12 “To Determine the unconfined compressive strength of a cohesive soil sample.” ....................................................................................... 12 Objective: ................................................................................................................................ 12 Need and scope: ...................................................................................................................... 12 Procedure: .............................................................................................................................. 13 Calculations: ........................................................................................................................... 13 Data: ........................................................................................................................................ 14 Graph: ..................................................................................................................................... 14

Experiment # 3 ................................................................................... 15 “Unconsolidated-Undrained

Triaxial

Compression

Test

on

Cohesive Soils” ................................................................................... 15 Objective: ................................................................................................................................ 15 Need And Scope: .................................................................................................................... 15

Civil Department, UET Peshawar

2|Page

GEOTECH-II CE-313L

Group Report

Apparatus ............................................................................................................................... 15 Procedure: .............................................................................................................................. 16 Results And Calculations ...................................................................................................... 16 Table: ...................................................................................................................................... 17 GRAPH: .................................................................................................................................. 19 Result: ..................................................................................................................................... 19

Experiment # 4: Shear Strength of Soil by Vane Shear Test ........... 20 Objective: ................................................................................................................................ 20 Apparatus:-............................................................................................................................. 20 Procedure of Vane Shear Test:-............................................................................................ 21 Observations and Calculations of Vane Shear Test............................................................ 22 Result of Vane Shear Test: .................................................................................................... 23 Advantages of Vane Shear Test:........................................................................................... 23 Drawbacks of Vane Shear Test............................................................................................. 23

Experiment # 5 “Consolidation Test On Soil” ........................................... 24 Objective: ................................................................................................................................ 24 Significance and Use: ............................................................................................................. 24 Apparatus Required for Consolidation Test: ...................................................................... 24 Consolidation Test Procedure: ............................................................................................. 25 Observations for Consolidation Test of Soil:....................................................................... 27 Calculations for Consolidation Test of Soil: ........................................................................ 28 Graphs to be plotted: ............................................................................................................. 28 Results of Consolidation Test of Soil: .................................................................................. 31

Experiment # 6 “Standard Penetration Test (SPT)” ............................. 32 ASTM designation ................................................................................................................... 32 Objective: ................................................................................................................................ 32

Civil Department, UET Peshawar

3|Page

GEOTECH-II CE-313L

Group Report

Significance and Use: ............................................................................................................. 32 Standard Penetration Test (SPT) Theory ................................................................................. 32 Apparatus Required for Consolidation Test: ...................................................................... 32 Test Procedure: ...................................................................................................................... 33 Corrections in Standard Penetration Test: ......................................................................... 33 1. Dilatancy Correction: ........................................................................................................... 33 2. Overburden Pressure Correction:......................................................................................... 34 Advantages of Standard Penetration Test ................................................................................ 34 Disadvantages of Standard Penetration Test............................................................................ 34 Standardized SPT Data Corrections:................................................................................... 35 Observations for Standard Penetration Test: ..................................................................... 36 Bearing Capacity of Soil:- ..................................................................................................... 37 1.

Meyerhof’s Equations: .................................................................................................. 37

2.

Bowles’ Equations: ....................................................................................................... 38

Experiment: ASTM Designation:

Plate Load Test............................................................... 39 D 1194-94 .............................................................................. 39

Objective: ................................................................................................................................ 39 Need and Scope: ..................................................................................................................... 39 Apparatus: .............................................................................................................................. 39 Procedure: .............................................................................................................................. 40 Calculation of Bearing Capacity from Plate Load Test: .................................................... 41 Bearing Capacity Calculation for Clayey Soils ....................................................................... 41 Bearing Capacity Calculation for Sandy Soils......................................................................... 41 Calculation of Foundation Settlement from Plate Load Test: ................................................. 41 Foundation Settlement Calculation on Clayey Soils ............................................................... 41 Foundation Settlement Calculation on Sandy Soils ................................................................. 42 Calculations: ........................................................................................................................... 42 Conclusion: ............................................................................................................................. 42 References:

Civil Department, UET Peshawar

46

4|Page

GEOTECH-II CE-313L

Experiment 1:

Group Report

“Direct shear test”

Objective: To determine the shearing strength of the soil using the direct shear apparatus.

Need and scope: 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 cover the laboratory procedures for determining these values for cohesion less soils.

Planning and organization: Apparatus: 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 upto 200 mg. 8. Aluminum container. 9. Spatula. APPARATUS

Knowledge of equipment: Strain controlled direct shear machine consists of shear box, soil container, loading unit, proving ring, dial gauge to measure shear deformation and volume changes. A two piece square shear box is one type of soil container used. Civil Department, UET Peshawar

5|Page

GEOTECH-II CE-313L

Group Report

A proving ring is used to indicate the shear load taken by the soil initiated in the shearing plane.

Procedure: 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

Civil Department, UET Peshawar

6|Page

GEOTECH-II CE-313L

Group Report

Parts of Apparatus: 1. Direct shear box apparatus, and Loading frame (motor attached) 2. Dial gauge for vertical deformation measurement 3. Dial gauge for horizontal deformation measurement 4. Proving ring for Shear force measurement. Loads are kept in loading frame for application of normal stress 5. Components of shear box with porous stone, filter paper etc.

Civil Department, UET Peshawar

7|Page

GEOTECH-II CE-313L

Group Report

Data: 1) Normal stress 0.5 kg/cm2 L.C=0.01 P.R.C=0.425

Horizontal Gauge Reading

Proving Ring Reading

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000

0 16 21 26 29 33 35 37 38 39 40 40 41 41 41 42 46 46 46 46 45

Horizontal/shear Shear Deformation Force (kg) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10

Shear Stress

0 6.8 8.925 11.05 12.325 14.025 14.875 15.725 16.15 16.575 17 17 17.425 17.425 17.425 17.85 19.55 19.55 19.55 19.55 19.125

0.000 0.241 0.316 0.391 0.436 0.496 0.526 0.556 0.571 0.586 0.601 0.601 0.616 0.616 0.616 0.631 0.692 0.692 0.692 0.692 0.677

2) Normal stress 1.0 kg/cm2 L.C=0.01 P.R.C=0.425 Horizontal Gauge Reading 50 100 150 200 250 300 350 400 450 500 550 600 650 700

Proving Ring Reading

Horizontal/shear Deformation

Shear Force (kg)

Shear Stress

13 17 20 23 24 26 27 27 28 28 29 29 29 29

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

5.525 7.225 8.5 9.775 10.2 11.05 11.475 11.475 11.9 11.9 12.325 12.325 12.325 12.325

0.195 0.256 0.301 0.346 0.361 0.391 0.406 0.406 0.421 0.421 0.436 0.436 0.436 0.436

Civil Department, UET Peshawar

8|Page

GEOTECH-II CE-313L

Group Report

3) Normal stress 1.5 kg/cm2 L.C=0.01 P.R.C=0.425 Horizontal Gauge reading 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000

Proving Ring Reading 14 16 17 17 18 19 19 20 20 21 21 21 21 22 23 23 24 25 25 24

Horizontal/shear Deformation

Shear Force (kg)

Shear Stress

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10

5.95 6.8 7.225 7.225 7.65 8.075 8.075 8.5 8.5 8.925 8.925 8.925 8.925 9.35 9.775 9.775 10.2 10.625 10.625 10.2

0.210 0.241 0.256 0.256 0.271 0.286 0.286 0.301 0.301 0.316 0.316 0.316 0.316 0.331 0.346 0.346 0.361 0.376 0.376 0.361

4) Normal stress 2.0 kg/cm2 L.C=0.01 P.R.C=0.425 Horizontal Gauge Reading

Proving Ring Reading

Horizontal/shear Deformation

Shear Force (kg)

Shear Stress

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950

26 40 52 61 69 74 79 83 87 89 90 90 89 87 86 84 83 82 81

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950

11.05 17 22.1 25.925 29.325 31.45 33.575 35.275 36.975 37.825 38.25 38.25 37.825 36.975 36.55 35.7 35.275 34.85 34.425

0.391 0.601 0.782 0.917 1.037 1.112 1.188 1.248 1.308 1.338 1.353 1.353 1.338 1.308 1.293 1.263 1.248 1.233 1.218

Civil Department, UET Peshawar

9|Page

GEOTECH-II CE-313L

Group Report

Graphs: Graph # 1 Shear Stress vs Horizontal Displacement Curve 1.6 1.4

Normal Stress 0.5 kg/cm^2

Shear Stress ()KPa)

1.2

Normal Stress 1 kg/cm^2

1

Normal Stress 1.5 kg/cm^2

0.8 0.6

Normal Stress 2 kg/cm^2

0.4 0.2 0 0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

9.5 10

Horizontal Displacement (mm)

Graph # 2 Shear Stress vs Normal Stress 1.6

Shear stress (Kg/cm^2)

1.4 1.2

y = 0.3786x + 0.2335

1 0.8 0.6 0.4 0.2 0

0

0.5

1

1.5

2

2.5

Normal Stress (kg/cm^2)

Civil Department, UET Peshawar

10 | P a g e

GEOTECH-II CE-313L

Group Report

Conclusion:  Cohesion = 0.2335  Internal friction angle = 21o

General Remarks: 1. In the shear box test, the specimen is not failing along its weakest plane but along a predetermined or induced failure plane i.e. horizontal plane separating the two halves of the shear box. This is the main drawback of this test. Moreover, during loading, the state of stress cannot be evaluated. It can be evaluated only at failure condition i.e. Mohr’s ...