Geotechnical Engineering 2018 Question Paper — Government College of…

Instructions

• Attempt five questions in all selecting at least one question from each unit.
• All questions carry equal marks.
• Assume missing data, if any, suitably.

Questions

Unit-I

• Q1. (a) One cubic meter of wet soil weighs 19.8 kN. If the specific gravity of particles is 2.7 and water content is 11%, find the void ratio, dry density and degree of saturation. 10 (b) 25 kg of dry soil was subjected to sieve analysis. The weight of the soil retained in each sieve is as given in the table below. Determine the effective size of the soil. Draw the particle size distribution curve and determine the uniformity coefficient and coefficient of curvature and comment on the result : 10 | Sieve size | Mass of soil retained (kg) | | :--- | :--- | | 2 mm | 0 | | 1 mm | 2.02 | | 0.6 mm | 3.51 | | $425\ \mu$ | 7.53 | | $212\ \mu$ | 8.15 | | $150\ \mu$ | 2.81 | | $75\ \mu$ | 0.90 | | pan | 0.08 | [20 marks]
• Q2. (a) In a hydrometer analysis 50 g of soil was mixed in water to form 1000 ml uniform soil suspension. The corrected hydrometer reading after a lapse of 60 mts from the start of sedimentation was 1.010 and the corresponding effective depth was 108 mm. Determine the effective diameter corresponding to 60 mts reading and percentage of particles finer than this size. G = 2.7 viscosity of water is $0.001\ \text{Ns}/\text{m}^2$. 10 (b) What are the major soil deposits of India ? Explain their characteristics. 10 [20 marks]

Unit-II

• Q3. (a) A soil strata consists of 3 layers of thickness 1 m, 1.5 m and 2.0 m having the coefficient of permeability of $2 \times 10^{-3}\ \text{cm}/\text{s}$, $1.5 \times 10^{-3}\ \text{cm}/\text{s}$ and $3 \times 10^{-3}\ \text{cm}/\text{s}$ respectively. Estimate the average coefficient of permeability in the direction (i) parallel to the bedding plane (ii) normal to the bedding plane. 10 (b) What is a flow net ? Describe its properties and applications, also the different methods of its construction. 10 [20 marks]
• Q4. (a) In a site reclamation project, 2.5 m of graded fill ($\gamma = 22\ \text{kN}/\text{m}^3$) were laid in compacted layers over an existing layer of silty clay ($\gamma = 18\ \text{kN}/\text{m}^3$) which was 3 m thick. This was underlain by a 2 m thick layer of gravel ($\gamma = 20\ \text{kN}/\text{m}^3$). Assuming that the water table remains at the surface of the silty clay draw the effective stress profiles for cases (i) before fill is placed (ii) after the fill has been placed. 10 (b) Write a note on the factors affecting coefficient of permeability. 10 [20 marks]

Unit-III

• Q5. (a) Define compression index. How can it be determined from a consolidation test ? Distinguish between normally consolidated soil, under-consolidated soil and an over-consolidated soil. 10 (b) In a consolidation test the pressure on a sample was increased from 150 to $300\ \text{kN}/\text{m}^2$. The void ratio after 100% consolidation under $150\ \text{kN}/\text{m}^2$ was 0.945, and that under $300\ \text{kN}/\text{m}^2$ was 0.812. The coefficient of permeability of the soil was $25 \times 10^{-6}\ \text{mm}/\text{s}$ and the initial height of the sample was 20 mm. Determine (i) the coefficient of compressibility, (ii) the coefficient of volume compressibility. 10 [20 marks]
• Q6. (a) State field methods of compaction. Explain suitability of various compaction equipments. 10 (b) Describe standard proctor test and the modified proctor test. How would you decide the type of test to be conducted in the laboratory ? 10 [20 marks]

Unit-IV

• Q7. (a) The results of two drained triaxial tests on saturated clay are given below : 10 Specimen 1 : $\sigma = 69\ \text{kN}/\text{m}^2$, $\sigma_d = 213\ \text{kN}/\text{m}^2$ Specimen 2 : $\sigma = 120\ \text{kN}/\text{m}^2$, $\sigma_d = 258.7\ \text{kN}/\text{m}^2$ Calculate shear strength parameters of the soil. (b) An unconfined compression test was conducted on an undisturbed sample of clay. The sample had a diameter of 38 mm and length 76 mm. The load at failure was 30 N and the axial deformation of the sample 11 mm. Determine the untrained shear strength parameters, if the failure plane made an angle of 50 with horizontal. 10 [20 marks]
• Q8. (a) Describe Mohr's theory of shear failure of soil with sketch. 10 (b) Explain the three standard triaxial shear tests with respect to drainage conditions ? Explain with reasons the situations for which each test is to be preferred. 10 [20 marks]

Related pages

• Geotechnical Engineering syllabus
• All Geotechnical Engineering papers from 2018

Other years

• Geotechnical Engineering 2022 question paper — end-term
• Geotechnical Engineering 2022 question paper — end-term