# Soil Mechanics

## Trending Questions

**Q.**

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

- 1.5 g/cc and 1.0 g/cc
- 2.0 g/cc and 1.0 g/cc
- 2.25 g/cc and 1.25 g/cc
- 2.50 g/cc and 1.50 g/cc

**Q.**A cohesive soil yields a maximum dry density of 1.8 g/cc at an OMC of 16% during a Standard Proctor test. If the value of G is 2.65, the maximum dry density it can be further compacted to is ____ g/cc

- 1.86

**Q.**A soil has mass unit weight γ, water content 'w' (as ratio). The specific gravity of soil solids = G, unit weight of water =γw. 'S' the degree of saturation of the soil is given by

S=1+wγwγ(1+w)−1G

- S=wγwγ(1+w)−1G
- S=(1+w)γwγ(1+w)−1G
- S=wγwγ(1+w)−1wG

**Q.**Consider the following statements:

Phreatic line in an earth dam is

1. elliptical in shape

2. an equipotential line

3. the top most flow line with zero water pressure

4. approximately a parabola

Which of these statements is/are correct?

- 1, 2 and 3
- 2, 3 and 4
- 3 and 4
- 1 alone

**Q.**A consolidation undrained (CU) triaxial compression test is conducted on a normally consolidated clay at a confining pressure of 100 kPa. The deviator stress at failure is 80 kPa, and the pore-water pressure measured at failure is 50 kPa. The effective angle of internal friction (in degrees, up to one decimal place) of the soil is

- 26.38

**Q.**The water content of a saturated soil and specific gravity of soil solids were found to be 30% and 2.70 respectively. Assuming the unit wt of water to be 10 kN/m3, the saturated unit wt (kN/m3) and the void ratio of the soil are

- 19.4, 0.81
- 18.5, 0.30
- 19.4, 0.45
- 18.5, 0.45

**Q.**Due to rise in temperature, the viscosity and unit weight of percolating fluid are reduced to 70% and 90% respectively. Other things being constant, the change in coefficient of permeability will be

- 20.0%
- 28.6%
- 63.0%
- 77.8%

**Q.**The ratio of saturated unit weight to dry unit weight of a soil is 1.25. If the specific gravity of solids (Gs) is 2.65, the void ratio of the soil is

- 0.625
- 0.663
- 0.944
- 1.325

**Q.**Quick sand condition occurs when

- void ratio of the soil becomes 1.0
- upward seepage pressure in soil becomes zero
- upward seepage pressure in soil becomes equal to the saturated unit weight of the soil
- upward seepage pressure in soil becomes equal to the submerged unit weight of the soil

**Q.**Sheep-foot rollers are recommended for compacting

- granular soils
- cohesive soil
- hard rock
- any type of soil

**Q.**A soil has dry unit weight of 15.5 kN/m2, specific gravity of 2.65 and degree of saturation of 72%. Considering the unit weight of water as 10 kN/m3 , the water content of the soil (in % round off to two decimal places) is

- 19.26

**Q.**Based on grain distribution analysis, the D10, D30 and D60 values of a given soil are 0.23 mm, 0.3 mm and 0.41 mm respectively. As per IS code, the soil classification will be

- SW
- SP
- SM
- SC

**Q.**A 10m thick clay layer is underlain by a sand layer of 20m depth (see figure). The water table is 5 m below the surface of clay layer. The soil above the water table is capillary saturated. The value of γsat is 19 kN/m3. The unit weight of water is γw. If now the water table raises to the surface. The effective stress at a point P on the interface will be

- Increase by 5γw
- Remain unchanged
- Decreases by 5γw
- Decreases by 10γw

**Q.**Consistency Index of a clayey soil is [LL = Liquid Limit, PL = Plastic Limit, PI = Plasticity Index, w = Natural moisture content]

- LL−wPI
- w−LLPI
- LL−PL
- 0.5 w

**Q.**In a direct shear test, the shear stress and normal stress on a dry sand sample at failure are 0.6 kg/cm2 and 1 kg/cm2 respectively. The angle of internal friction of the sand will be nearly.

- 25o
- 31o
- 37o
- 43o

**Q.**A soil sample has a shrinkage limit of 10% and specific gravity of soil as 2.7. The porosity of the soil at shrinkage limit is

- 21.2%
- 27%
- 73%
- 78.8%

**Q.**The laboratory test results of a soil sample are given below

Percentage finer than 4.75 mm = 60

Percentage finer than 0.075 mm = 30

Liquid Limit = 35%; Plastic Limit = 27%

The soil classification is

- GM
- SM
- GC
- ML-MI

**Q.**A soil deposit has a void ratio of 1.0. if the void ratio is reduced to 0.60 by compaction, the percentage volume loss is

- 10%
- 20%
- 30%
- 40%

**Q.**The shear strength of a cohesionless soil is

- Proportional to the angle of shearing resistance
- Inversely proportional to the angle of shearing resistance
- Proportional to the tangent of the angle of shearing resistance
- None of the above

**Q.**If a soil sample of weight 0.18 kg having a volume of 10−4m3 and dry unit weight of 1600kg/m3 is mixed with 0.02kg of water then the water content in the sample will be

- 30%
- 25%
- 20%
- 15%

**Q.**Consider the following statements:

A well-graded sand should have

1. uniformity coefficient greater than 6

2. coefficient of curvature between 1 and 3

3. effective size greater than 1 mm

Which of these statements are correct?

- 1, 2 and 3
- 1 and 2
- 1 and 3
- 2 and 3

**Q.**The coefficient of permeability of a soil in horizontal and vertical directions are 3.46 and 1.5 m/day respectively. The base length of a concrete dam resting in this soil is 100 m. When the flow net is developed for this soil with 1:25 scale factor in the vertical direction, the reduced base length of the dam will be

- 2.63 m
- 4.00 m
- 6.08 m
- 5.43 m

**Q.**A soil fails under an axial vertical stress of 100 kN/m2 in unconfined compression test. The failure plane makes an angle of 50° with the horizontal. The shear parameters ′c′ and ′Φ′ respectively will be

- 41.9 kN/m2, 0o
- 50.0 kN/m2, 0o
- 41.9 kN/m2, 0o
- 50.0 kN/m2, 0o

**Q.**The saturated and dry densities of a soil are respectively 2000kg/m3 and 1500kg/m3. The water content (in percentage) of the soil in the saturated state would be

- 25
- 33.33
- 50
- 66.66

**Q.**What does the confining pressure used in triaxial compression tests on an undisturbed soil sample represent?

- The in-situ total normal stress
- The in-situ total lateral stress
- The in-situ effective principal stress
- The in-situ shear stress

**Q.**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. Axial stress (in kN/m2) at failure would be

- 150
- 200
- 250
- 300

**Q.**A and B are Skempton's pore pressure coefficients. For saturated normally consolidated soils,

- A>1 and B>1
- A>1 and B<1
- A<1 and B>1
- A<1 and B=1

**Q.**Laboratory vane shear test can also be used to determine

- shear parameters of silty sand
- shear parameters of sandy clay
- liquid limit of silty clay
- plastic limit of clayey silt

**Q.**A dry soil has mass specific gravity of 1.35. If the specific gravity of solids is 2.7, then the void ratio will be

- 0.5
- 1.0
- 1.5
- 2.0

**Q.**A clayey soil has a maximum dry density of 16 kN/m3 and optimum moisture content of 12%. A contractor during the construction of core of an earth dam obtained the dry density 15.2kN/m3 and water content 11%. This construction is acceptable because

- The density is less than the maximum dry density and water content is on dry side of optimum
- The compaction density is very low and water content is less than 12%
- The compaction is done on the dry side of the optimum
- Both the dry density and water content of the compacted soil are within the desirable limits