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# Soil Mechanics (281-300)

Updated: Apr 27, 2020

281. A soil has a bulk density of 1.80 g/cm³ at a water content of 5%. If the void ratio

remains constant, then its bulk density for a water content of 10% will be 1.88 g/cm³

282.

1.Initiation of piping under hydraulic structures can be prevented by increasing the length of flow path of water

2.Seepage pressure is independent of the coefficient of permeability

283. The appropriate triaxial test to assess the long-term stability of an unloading

problem, such as excavation of a clay slope, would be the consolidated-drained test

284. For a sandy soil, the angle of internal friction is 30°. If the major principal stress is 50 kN/m² at failure, then the corresponding minor principal stress (in

kN/m²) will be 16.66

285. If a sample of dry sand tested in direct shear test gives failure shear stress τf as 1 kg/cm² at a normal stress σf of 2 kg/cm², then the angle of internal friction of soil is given by

286. Given:

μ₁ = Poisson's ratio of soil sample 1

μ₂ = Poisson's ratio of soil sample 2

k = coefficient of earth pressure at rest for soil sample 1

k = coefficient of earth pressure at rest for soil sample 2

If μ₁/μ₂ = 1.5 and (l-μ₁)/(l-μ₂) = 0.875, then the value of k₁/k will be 1.7143

287. The Factor of Safety of an infinite slope in a sand deposit is found to be 1.732. The angle of shearing resistance of the sand is 30°. The average slope of the sand deposit is given by

288. A normally consolidated clay layer settles1 cm when the pressure increases from I kg/cm² to 2 kg/cm². Additional settlement for the same soil for further increase of pressure from 2 kg/cm² to 4 kg/cm² will be. 2cm

289. In the soil sample of a consolidometer test, pore water pressure is maximum at the centre

290. Under load, the void ratio of a submerged saturated clay decreases from 1.00 to 0.92. What will be the ultimate settlement of the 2 m thick clay due to consolidation? 80 mm

291. The gross bearing capacity of a footing is 450 kN/m². If the footing is 1.5 m wide at a depth of 1 m in clayey soil with unit weight of 20 kN/m³, then the net bearing capacity (in kN/m²) will be 430

292. Permissible settlement is relatively higher for rafts on clays

293. Given :

For a damped vibrating foundation system with single degree of freedom

C = damping constant,

Cc = critical damping coefficient,

δ = logarithmic decrement,

the relationship between C, Cc and 8 is

given by. 294. For undisturbed sampling, the area ratio for a thin-wall sampler should not

normally exceed 15%

295.

1. Standard penetration test.... Relative density

2. Vane shear .... Cohesion

296.

A. Well-graded gravel sand mixtures with little or no fines -GW B. Poorly graded sands or gravelly sands with little or no fines - SP C. Inorganic silts and very fine sands or clayey silts with low plasticity - ML D. Inorganic clays of high plasticity - CH

297. A sample of soil has the following properties:

Liquid limit = 45%

Plastic limit = 25%

Shrinkage limit = 17%

Natural moisture content = 30%

The consistency index of the soil is 15/20

298. A stratum of soil consists of three layers of equal thickness. The permeabilities of top and bottom layers are K = 10⁻⁴ cm/s and that of the middle layer is K = 10⁻³

cm/s. Then the value of the horizontal coefficient of permeability KH for the

entire soil layers is 4xl0⁻⁴cm/s cm/s

299. The ratio of the energies imparted to soil sample in modified Proctor's compaction 4.5

300. 1) Flow lines are perpendicular to equipotential lines.

2) No two flow lines or equipotential lines startfromthe same point.

3) No two flow lines cross each other