Soil Mechanics

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. 1.5 g/cc and 1.0 g/cc
2. 2.0 g/cc and 1.0 g/cc
3. 2.25 g/cc and 1.25 g/cc
4. 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. 1.86

Q. A soil has mass unit weight $\gamma$, water content 'w' (as ratio). The specific gravity of soil solids = G, unit weight of water =${\gamma }_w$. 'S' the degree of saturation of the soil is given by

1. $S=\frac{1+w}{\frac{\gamma w}{\gamma }(1+w)-\frac{1}{G}}$

2. $S=\frac{w}{\frac{\gamma w}{\gamma }(1+w)-\frac{1}{G}}$
3. $S=\frac{(1+w)}{\frac{\gamma w}{\gamma }(1+w)-\frac{1}{G}}$
4. $S=\frac{w}{\frac{\gamma w}{\gamma }(1+w)-\frac{1}{wG}}$
   

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. 1, 2 and 3
2. 2, 3 and 4
3. 3 and 4
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

1. 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 $10kN/m^3$, the saturated unit wt (kN/$m^3$) and the void ratio of the soil are

1. 19.4, 0.81
2. 18.5, 0.30
3. 19.4, 0.45
4. 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

1. 20.0%
2. 28.6%
3. 63.0%
4. 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 $\left(G_s\right)$ is 2.65, the void ratio of the soil is

1. 0.625
2. 0.663
3. 0.944
4. 1.325

Q. Quick sand condition occurs when

1. void ratio of the soil becomes 1.0
2. upward seepage pressure in soil becomes zero
3. upward seepage pressure in soil becomes equal to the saturated unit weight of the soil
4. upward seepage pressure in soil becomes equal to the submerged unit weight of the soil

Q. Sheep-foot rollers are recommended for compacting

1. granular soils
2. cohesive soil
3. hard rock
4. any type of soil

Q. A soil has dry unit weight of $15.5kN/m^2$, specific gravity of 2.65 and degree of saturation of 72%. Considering the unit weight of water as $10kN/m^3$ , the water content of the soil (in % round off to two decimal places) is

1. 19.26

Q. Based on grain distribution analysis, the $D_{10}$, $D_{30}$ and $D_{60}$ 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

1. SW
2. SP
3. SM
4. 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 ${\gamma }_{sat}$ is 19 kN/$m^3$. The unit weight of water is ${\gamma }_w$. If now the water table raises to the surface. The effective stress at a point P on the interface will be

1. Increase by 5${\gamma }_w$
2. Remain unchanged
3. Decreases by 5${\gamma }_w$
4. Decreases by 10${\gamma }_w$

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

1. $\frac{LL-w}{PI}$
2. $\frac{w-LL}{PI}$
3. $LL-PL$
4. 0.5 w

Q. In a direct shear test, the shear stress and normal stress on a dry sand sample at failure are $0.6kg/c{m}^2$ and $1kg/c{m}^2$ respectively. The angle of internal friction of the sand will be nearly.

1. ${25}^o$
2. ${31}^o$
3. ${37}^o$
4. ${43}^o$

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

1. 21.2%
2. 27%
3. 73%
4. 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

1. GM
2. SM
3. GC
4. 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

1. 10%
2. 20%
3. 30%
4. 40%

Q. The shear strength of a cohesionless soil is

1. Proportional to the angle of shearing resistance
2. Inversely proportional to the angle of shearing resistance
3. Proportional to the tangent of the angle of shearing resistance
4. None of the above

Q. If a soil sample of weight 0.18 kg having a volume of ${10}^{-4}{m}^3$ and dry unit weight of $1600kg/m^3$ is mixed with 0.02kg of water then the water content in the sample will be

1. 30%
2. 25%
3. 20%
4. 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. 1, 2 and 3
2. 1 and 2
3. 1 and 3
4. 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

1. 2.63 m
2. 4.00 m
3. 6.08 m
4. 5.43 m

Q. A soil fails under an axial vertical stress of $100kN/m^2$ in unconfined compression test. The failure plane makes an angle of $50°$ with the horizontal. The shear parameters ${}^{\prime }{c}^{\prime }$ and ${}^{\prime }{\Phi }^{\prime }$ respectively will be

1. $41.9kN/m^2,0^o$
2. $50.0kN/m^2,0^o$
3. $41.9kN/m^2,0^o$
4. $50.0kN/m^2,0^o$

Q. The saturated and dry densities of a soil are respectively $2000kg/m^3$ and $1500kg/m^3$. The water content (in percentage) of the soil in the saturated state would be

1. 25
2. 33.33
3. 50
4. 66.66

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

1. The in-situ total normal stress
2. The in-situ total lateral stress
3. The in-situ effective principal stress
4. The in-situ shear stress

Q. A clay soil specimen when tested in unconfined condition gave an unconfined compressive strength of $100kN/m^2$. A specimen of the same clay with the same initial condition is subjected to a $UU$ triaxial test under a cell pressure of $100kN/m^2$. Axial stress $($in $kN/m^2)$ at failure would be

1. $150$
2. $200$
3. $250$
4. $300$

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

1. $A>1$ and $B>1$
2. $A>1$ and $B<1$
3. $A<1$ and $B>1$
4. $A<1$ and $B=1$

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

1. shear parameters of silty sand
2. shear parameters of sandy clay
3. liquid limit of silty clay
4. 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

1. 0.5
2. 1.0
3. 1.5
4. 2.0

Q. A clayey soil has a maximum dry density of 16 kN/$m^3$ and optimum moisture content of 12%. A contractor during the construction of core of an earth dam obtained the dry density 15.2kN/$m^3$ and water content 11%. This construction is acceptable because

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