Soil Mechanics (221-240)

Updated: Apr 27, 2020

221. Compression index on a soil helps to determine total settlement of clay layer

222. When the degree of consolidation is 50%, the time factor is about 0.2

223. According to Bousine,sq's theory, the vertical stress at a point in a semi-infinite soil mass depends upon point load and coordinates of the point


224. The process by which a mass of saturated soil is caused by external forces to

suddenly lose its shear strength and to behave as a fluid is called liquefaction



225. By using sieve analysis, the particle size distribution curve has been plotted for a particular soil. The coefficient of curvature Cc is given by




226. Given below are methods of compaction:

1. Vibration technique

2. Flooding the soil

3. Heavy weights dropped from a height

The methods suitable for cohesionless soils include

227. Consider the following factors pertaining to flow through soil:

1. Grain size

2. Void ratio

228. Which one of the following, gives the correct decreasing order of the densities of a soil sample?

Saturated, wet, dry, submerged

229. For sampling saturated sands and other soft and wet soils satisfactorily, the most suitable soil sampler is standard split-spoon sampler

230.

Condition under which it is suited - Type of foundation A. When structural load is uniform and soil is soft clay, made up of marshy land-Raft B. When structural load is heavy and/or soil having low bearing capacity for a considerable depth-Piles C. When soil is having good bearing capacity at shallow depth and structural load is within permissible limit-Footings D. When structural load of bridge is to be transferred through sandy soil to bed rock-Wells or pier

231.Figure 8.7 shows the relation between void ratio and shear strain for a sand under two density conditions. The void ratio corresponding to the dashed line is called


critical void ratio

232. A vane shear test on a soil sample gives moment of total resistance M. The shear stress failure, 'S' being more or less uniform at top, bottom and surface of

cylinder of coil, is given by (where H = height of vane, D= Diameter of vane)




233. The following refer to the stability analysis of an earth dam under different

conditions:.

1. Stability of D/S slope during steady seepage

2. Stability of U/S slope during sudden drawdown

3. Stability of U/S and D/S slopes during construction

234. If the settlement of a single pile in sand is denoted by S and that of a group of N identical piles (each pile carrying the same load) by Sg, then the ratio Sg/S will

increase as the width of the group increases

235.









236.Feild test- Useful for Vane shear test-Soft clay Standard penetration test-Sandy deposits Static cone penetration test- End bearing and skin friction resistance Pressure meter test- In-situ stressstrain characteristics


237.Consider the following statements regarding settlement of foundations

1. Differential settlement of foundation leads to structural damage to the superstructure.

2.Lowering of ground water table contributes to settlement of foundations.

238. Consider the following types of soil tests:

1. Consolidation

2. Unconfined compression

The soil tests required to be done in the case of undisturbed samples include

239.

Auger boring- Partly saturated sands, silts and medium to stiff cohesive soils Wash boring- Practically all types of soils except hard and cemented soil or rock Percussion drilling-All types of soils and rocks. Difficult in loose sands and soft sticky clays Rotary drilling-All types of soils and rocks except in stony or porous soils and fissured rocks

240. Consider the following statements: Clays which exhibit high activity

1. contain montmorillonite.

2. have a high plasticity index



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