Soil Mechanics (201-220)

Updated: Apr 27, 2020

201.

Bearing capacity terms- Definition A.Ultimate bearing capacity-Minimum gross pressure intensity at the base of foundation at which soil fails in shear B.Net safe bearing capacity-Net ultimate bearing capacity divided by factor of safety C. Safe bearing capacity- The maximum pressure which soil can carry safely without risk of shear failure D. Allowable bearing pressure- Net loading intensity at which neither soil fails in shear nor is there any excessive settlement

202. A building is supported on shallow foundation in sand at 1 m below ground

level. The water table is at 5 m below the ground surface. For which one of the

following foundations will the net bearing capacity of the soil be a maximum?

2 m wide strip footing

203. The determination of ultimate bearing capacity on an eccentrically loaded square footing depends upon the concept of useful width


204. Figure shows the contact pressure distribution in pure clayey soil subjected to a uniformly distributed load (udl) through rigid footing (placed on the surface).



Which of the following would cause the contact pressure distribution maximum at the centre and decrease towards the outer edges leading to parabolic shape?

When udl is transmitted through rigid footing placed on the surface of a cohesionless soil.

205.A cast-in-situ bored pile 0.50 m diameter and 10 m deep is placed in a purely

cohesive soil. If the cohesion of the soil is 4t/m² and adhesion between the pile and the soil is half the value of cohesion, then the ultimate bearing capacity of the pile is given by 49π/4 tonnes


206.A test concrete block is subjected to vertical vibration and resonance occurred at a frequency of 20 cycles per second. If mass of vibration is 6 kg and mass of foundation is 244 kg, then the coefficient of elastic uniform compression of soil is 4π² x 10⁵kg/m³


207

Grain size- Pipette Specific gravity- Pycnometer Coefficient of permeability-Permeameter Cohesion-Vane shear apparatus

208. The upstream slope of an earth dam under steady seepage condition is

equipotential line

209. Consider the following statements related to triaxial test

1. Intermediate and minor principal stresses are equal.

2. Volume changes can be measured.

3. Field conditions can be simulated

210. A vane 20cm long and 10 cm in diameter was pressed into a soft marine clay at the bottom of a bore hole. Torque was applied gradually and failure occurred at 1000 kg cm. The cohesion of the clay in kg/cm² is 6/7π

211.Active Pressure-wall moves away from backfill Passive Pressure-Wall moves towards backfill Earth Pressure at Rest-No movement of wall

212.A cohesionless soil having an angle of shearing resistance of Φ, is standing at a

slope angle of i. The factor of safety of the slope is tan Φ/tan i

213.

Water present in the soil above water table- Water is in a state of tension upward seepage flow- Decrease in effective stress Downward seepage flow- Increase in effective stress Fluctuation of water level above ground level- No Change effective stress

214. In consolidation testing, curve fitting method is used to determine

coefficient of consolidation

215. Westergaard's analysis for stress distribution beneath loaded areas is

applicable to stratified soils




216. Consider the following characteristics of soil layer:

1. Poisson's ratio

2. Young's modulus

Westergaard's analysis for pressure distribution in soils utilises

217. A square footing is to be proportioned on a cohesionless soil with an average N value of 40. The allowable bearing pressure of this footing will be governed by

general shear failure

218. According to Skempton's formula for a surface footing of square shape, the net ultimate bearing capacity on a purely cohesive soil of cohesion c is

6.0 c

219. Undisturbed soil samples are required for conducting consolidation test

220. Soil pressure distribution below a rigid footing on the surface of a cohesive soil is minimum at the centre and maximum at edges



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