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# Soil Mechanics (261-280)

Updated: Apr 27, 2020

261.

Elastic settlement-Occurs within a short period Primary consolidation-Dissipation of excess pore water pressure Secondary consolidation-Compression and rearrangement of particles Creep-Constant effective stress with change in volume of soil

262.Given that for an overconsolidated clay soil deposit, the pressure under which the deposit has been fully consolidated in the past is 125 kN/m² and the present overburden pressure is 75 kN/m², the overconsolidation ratio of the soil deposit

125/75

263.

Stress distribution due to point load in homogeneous isotropic medium -Boussinesq Stress distribution due to point load in an anisotopic medium- Westergaard Influence chart for stress distribution in a rectangular area- Stein Brenner Influence chart for stress distribution in irregularly shaped areas- Newmark

264. Given that

A = contact area of foundation with soil, and

m = mass of machine plus foundation

Natural frequency of foundation soil system for analysis of machine

foundation shall be determined by Barken's method by using the equation

265.Figure relates to design features of samplers affecting soil disturbance. The area ratio of the soil sample is given by

266.The static cone penetration test and a standard penetration test are performed on a soil at a certain depth. The value of static cone penetration test is 8 MPa and the N value is 20. The soil met with at that depth is sandy silt

267. Which of the following have an influence on the value of permeability?

1. void ratio

2. degree of saturation

3. grain size

268.

Optimum moisture content-Maximum dry density Vibratory rollers- Compaction of granular soil Zero air void line- 100% saturation

269. In a flow net diagram, the length of the flow line in the last square is 2 m, the total head loss is 18 m and the number of potential drops is 12 0.75

270. A soil sample has 28 g of soil solids, 10 cu cm of voids, 9 g of water and specific gravity of soil grains of 2.7; consider the following statements in this regard:

1. The water content is 9/28 x 100%

2. The void ratio is 10 x 2.7/28

3. The porosity is 10 x 2.7/(28+10 x2.7)

271. A clear dry sand sample is tested in a direct shear test. The normal stress and the shear stress at failure are both equal to 120 kN/m² The angle of shearing resistance of the sand will be 45°

272. An initial cross-sectional area of a clay sample was 15 sq. cm. The failure strain

was 25% in an unconfined compression test. The corrected area of the sample at

failure would be 20 sq cm

273.

Figure shows Culmann's graphical construction for earth pressure. 6 is the

angle of wall friction. The earth pressure line is represented by BC

274. A slope is to be constructed at an angle of 30° to the horizontal from a soil having the properties, C=15 kN/m2; Φ = 22.5°; γ = 19 kN/m³. Taylor's stability number is 0.046. If a factor of safety (with respect tocohesion) of 1.5 is required, then the safe height of the slope will be 11.5

275. A fully compensated raft foundation for a building is such that the weight of the excavated soil is equal to the load due to the building.

276. For a damped vibrating system with single degree of freedom, resonance

occurs at a frequency ratio of 1

277. At a site having a deposit of dry sandy soil, an average soil of standard

penetration resistance N equal to 6 was recorded. The compactness of the soil

deposit can be described as loose

278. Under a given load, a clay layer attains 30% degree of consolidation in 100 days. The time taken by the same clay layer to attain 60% degree of consolidation will be 400 days

279.Type of settlement- Notation on diagram A. Immediate settlement - L B. Primary consolidation -K C. Secondary compression - N D. Time-dependent settlement - M

280.Activity number-Plasticity index / Percent finer than 2 microns Liquidity index- (Natural moisture content - plastic limit)/Plasticity index Sensivity - Unconfined compressive strength of undisturbed soil sample/Unconfined compressive strength of remoulded soil sample