 MORE IN Geotechnical Engineering 1
VTU Civil Engineering (Semester 5)
Geotechnical Engineering 1
December 2014
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) With the help of three phase diagram, define the terms Bulk density, Dry density, void ratio and Water content.
8 M
1 (b) With usual notations prove that Se=WG.
6 M
1 (c) A soil sample weighing 19 kN/m3 has a water content of 30%. The specific gravity of soil particles is 2.68. Determine void ratio, porosity and degree of saturation.
6 M

2 (a) What is consistency of soil? List and define consistency limits.
6 M
2 (b) Briefly explain the correction to be applied to a hydrometer reading.
6 M
2 (c) Following results were obtained from liquid limit test on a clay sample, whose plastic limit is 20%.
Plot the curve and obtain; i) Liquid limit ii) Plasticity index iii) Flow index
 Number of blows 12 18 22 34 Water content in % 56 52 50 45
8 M

3 (a) Explain soil classification according to IS classification system.
8 M
3 (b) Explain any two field tests to identify silts from clays.
4 M
3 (c) With neat figures, explain the structures of three clay minerals.
8 M

4 (a) List of various factors affecting permeability of soils.
6 M
4 (b) Explain quick sand and capillary phenomena.
6 M
4 (c) In a falling head permeability test on a silty clay sample, the following results were obtained Length of sample =12cm; Diameter of sample=8cm; Diameter of stand pipe=0.4cm, Initial head of water in stand pipe=120cm; Final head of water in stand pipe=40cm, Time of fall in head =6 minutes. Find the coefficient of permeability of the soil.
8 M

5 (a) Explain Mohr-Coulomb theory.
6 M
5 (b) Explain Sensitivity and Thixotropy of clay.
6 M
5 (c) The result of shear box test are as follows:
Determine shear parameters, Would the failures occur on the plane within the soil mass when the shear stress in 122 kN/m2 and normal stress is 246 kN/m2?
 Normal Stress (kN/m2) 50 100 200 300 Shear stress (kN/m2) 36 80 154 235
8 M

6 (a) Write the differences between standard and modified proctor compaction test.
6 M
6 (b) Briefly explain factors affecting compaction.
6 M
6 (c) The following data were obtained from standard proctor compaction test:-
i) Plot the compaction and determine MDD and OMC.
ii) Draw zero-Gr. void line.
iii) Also determine saturation at MDD. Take G=2.6.
 Water content (%) 9 11 13 15 16 17 18 Bulk unit weight (kN/m3) 18 19 19.9 20.8 21 20.5 20.1
8 M

7 (a) Explain Mass-spring analogy.
6 M
7 (b) With neat sketch, explain how pre-consolidation pressure is determined by Casagrande's method.
6 M
7 (c) A soil sample 20mm thick takes 20minutes to reach 20% consolidation. Find the time taken for a clay 6m thick to reach 40% consolidation. Assume double drainage in both cases.
8 M

8 (a) What are the advantages and limitations of vane shear test? How do you conduct the test in laboratory?
8 M
8 (b) Explain square root of time fitting method for determination of coefficient of consolidation.
6 M
8 (c) With neat sketch, explain vane shear test.
6 M

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