Soil Mechanics (341-360)

Updated: Apr 27, 2020

341. A clay layer 5 m thick in field takes 300 days to attain 50% consolidation with

condition of double drainage. If the same clay layer is underlain by hard rock then

the time taken to attain 50% consolidation will be 1200 days

342.A clay layer 5 m thick in field takes 300 days to attain 50% consolidation with

condition of double drainage. If the same clay layer is underlain by hard rock then

the time taken to attain 50% consolidation will be 385 kn/m²



343. A 30 cm diameter friction pile is embedded 10 m into a homogeneous

consolidated deposit. Unit adhesion developed between clay and pile shaft is

4 t/m2 and adhesion factor is 0.7. The safe load for factor of safety 2.5 will be

10.55 t

344. In case of well foundation, grip length is defined as the

depth of the bottom of the well below the maximum scour level


345. In the following figures (Fig), if

H= height of wall above dredge line,

q = effective vertical stress at any depth,

c = unit cohesion,

and passive pressure is shown hatched in the figures, then the earth pressure

distribution diagram used for analysis of a cantilever sheet pile embedded to a depth D in a purely cohesive soil will be as in











346. A raft foundation is to be constructed on a sandy soil. The maximum differential settlement and limiting maximum settlement as recommended by Indian Standard code are


25 mm 40 mm to 65 mm

347. Consider the following statements:

1. twice the width of foundation.

2. the depth where the additional stress intensity is less than 10% of the over

burden pressure.

In subsoil exploration programme the term "significant depth of exploration" is up to



348. Lacustrine soils are soils deposited in lake beds


349. The standard plasticity chart to classify fine grained soils is shown in Fig. 8.23.



The area marked 'X' represents clay of intermediate plasticity

350. Consider the following statements in the context of aeolian soils:

1. The soil is deposited by wind.

2. The soil has large permeability

351. A soil has a liquid limit of 45% and lies above the A-line when plotted on a

plasticity chart. The group symbol of the soil as per IS Soil Classification is CI

352. The dry density of a soil is 1.5 g/cc. If the saturation water content were 50%, then its saturated density and submerged density would, respectively, be

2.25 g/cc and 1.25 g/cc

353. A fill having a volume of 1,50,000 cum is to be constructed at a void ratio of 0.8. The borrow pit soil has a void ratio of 1.4. The volume of soil required (in cubic metres) to be excavated from the borrow pit will be

2,00,000

354. The moisture content of a clayey soil is gradually decreased from a large value. What will be the correct sequence of the occurrence of the following limits?

1. Liquid limit.

2. Plastic limit.

3. Shrinkage limit.


355. Which one of the following equations correctly gives the relationship between the specific gravity of soil grains (G) and the hydraulic gradient (i) to initiate 'quick' condition in a sand having a void ratio of 0.5?

G = 1.5 i + 1

356.

Excessive Settlement - High compressibility High Expansivity - Montmorillonite Reduction of Bearing Capacity - Rise of water table Acceleration of Consolidation - Sand drains

357.A flow-net constructed to determine the seepage through an earth dam which is homogeneous but anisotropic, gave four flow channels and sixteen equipotential drops. The coefficients of permeability in the horizontal and vertical directions are 4.0 x 10⁻⁷ m/s and 1.0 x 10⁻⁷ m/s, respectively. If the storage head was 20 m, then the seepage per unit length of the dam (in m³/s) would be

10 x 10⁻⁷

358. A clay soil specimen when tested in unconfined condition gave an unconfined compressive strength of 100 kN/m². A specimen of the same clay with the same initial condition is subjected. to a UU triaxial test under a cell pressure of 100 kN/m². The axial stress (in kN/m ) a failure would be 200

359. If s is the shear strength, c and Φ are shear strength parameters, and σₙ is the normal stress at failure, then Coulomb's equation for shear strength of the soil can be represented by c= s - σₙ tan Φ

360.Earth pressure and resultant possibilities of wall movement are shown in Fig. The point marked 'X* in the diagram denotes.




passive earth pressure


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