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Subject Code:2150609
BE - SEMESTER-V (NEW) EXAMINATION — WINTER 2018
Subject Name:Soil Mechanics
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Date:04/12/2018
Time: 10:30 AM TO 01:00 PM
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Total Marks: 70
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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| Q.1 | (a) Write down short note on ' Earth Pressure at Rest'. | MARKS 03 |
| (b) Define Finite and Infinite Slopes. | 04 | |
| (c) Explain point to be considered for foundation in black cotton soil. | 07 | |
| OR | ||
| Q.2 | (a) Differentiate active earth pressure and passive earth pressure. | 03 |
| (b) Explain Rankine theory for active earth pressure in cohesive soil. | 04 | |
| (c) What are the graphical methods available for the determination of lateral earth pressure? Explain any one in detail. | 07 | |
| OR | ||
| Q.3 | (a) A retaining wall 8 m high, with vertical back supports cohesive soil backfill having unit weight 19 KN/m³ and angle of internal friction as zero and C =20 KN/m². Calculate (i) Internal pressure intensity at top (i1) Depth of tension crack (ii1) Lateral pressure intensity at base. | 07 |
| (b) Write down short note on Contact pressure. | 03 | |
| (c) For a point load of 150 KN, compute the vertical stress at 2.0 m depth along the axis by using Boussinesqand Westergaard's theories. Consider Poisson's ratio as zero. | 04 | |
| OR | ||
| Q.4 | (a) Describe the various assumption made in the derivation of Boussinesq theory. | 07 |
| (b) Describe usefulness of Isobar. | 03 | |
| (c) A raft of 4 m x 4 m carties a load of 200 KN/m². Determine vertical stress increment at a point 4 m below the centre of the loaded area using equivalent point load method. | 04 | |
| OR | ||
| Q.5 | (a) Derive an expression for vertical stress under a line load. | 07 |
| (b) Describe Zero air void line. | 03 | |
| (c) Explain different types of slope failure. | 04 | |
| OR | ||
| Q.5 | (a) The following data were obtained from Standard proctor test on a sample of soil. --- Content provided by FirstRanker.com --- Water content (%) 8 10.5 12 13.75 16 18 Wt of wet soil in (kg) 1.8 1.97 2.08 2 1.88 1.75 --- Content provided by FirstRanker.com --- The volume of mould is 1000 ml. Plot the compaction curve and calculate maximum dry density and optimum water content. | 07 |
| (b) Define compaction and its theory. | 03 | |
| (c) A vertical cut is made in clay deposit having C = 30 KN/m², f =0, ? = 16 KN/m³. Determine the maximum depth of cut so that the cut is stable. Take Sn = 0.261. | 04 | |
| OR | ||
| Q.5 | (a) Describe laboratory compaction test with its specification. | 07 |
| (b) Define compressibility and consolidation. | 03 | |
| (c) In an unconfined compressive test, a sample of clay 8 cm long and 4 cm in diameter fails under a load of 120 N at 10% strain. Compute the shearing resistance taking into account the effect of change in cross section of the sample. | 04 | |
| OR | ||
| Q.5 | (a) Define (1) Time factor (i1) coefficient of consolidation (iii) Degree of consolidation. | 07 |
| (b) Explain the phenomenon of consolidation of clay by Terzaghi's spring analogy. | 03 | |
| (c) During consolidation test, the void ratio decreases from 0.8 to 0.5 under the stress increment of 2 kg/cm² to 4 kg/cm’. Compute coefficient of compressibility, coefficient of volume compressibility and compression index. | 04 | |
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