Geography

Soil and Foundation Engineering

584 Questions

Soil and foundation engineering questions address the physical and mechanical properties of soil critical for construction and stability. The topics include shear strength, soil compaction, void ratios, and subsurface investigation techniques. These advanced geotechnical concepts are typically evaluated in civil engineering and specialized recruitment examinations.

Soil compactionShear strengthBearing capacityVoid ratio analysisSubsurface exploration

Soil and Foundation Engineering Questions

Multiple choice

A group of 16 piles of 10 m length and 0.5 diameter is installed in a 10 m thick stiff clay layer underlain by rock. The pile-soil adhesion factor is 0.4; average shear strength of soil on the sides is 100 kPa; undrained shear strength of the soil at the base is also 100 kPa.

The base resistance of single pile is

  1. 40.00 kN

  2. 88.35 kN

  3. 100.00 kN

  4. 176.71 kN
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Base resistance = Area * Nc * Cu. For a pile, Nc is typically 9. Area = pi/4 * 0.5^2 = 0.19635 m^2. Base resistance = 0.19635 * 9 * 100 = 176.71 kN.

Multiple choice

A group of 16 piles of 10 m length and 0.5 diameter is installed in a 10 m thick stiff clay layer underlain by rock. The pile-soil adhesion factor is 0.4; average shear strength of soil on the side on the sides is 100 kPa; undrained shear strength of the soil at the base is also 100 kPa.

Assuming 100% efficiency, the group side resistance is

  1. 5026.5 kN

  2. 10000.0 kN

  3. 10053.1 kN

  4. 20106.0 kN
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Group side resistance = Perimeter * Length * Adhesion * Shear Strength. Perimeter of group = 4 * (n*d + (n-1)*s). Assuming standard spacing, the calculation yields 10053.1 kN.

Multiple choice

A 6 m thick clay layer undergoes 90% consolidation four times faster under two-way drainage as compared to one-drainage. In an identical clay layer of 15 m thickness, two-way drainage will be faster as compared to one-way drainage by

  1. 8 times

  2. 4 times

  3. 2.5 times

  4. 2 times
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Time factor T_v = Cv * t / d^2. For same degree of consolidation, t is proportional to d^2. For two-way drainage, d = H/2. For one-way, d = H. Ratio of times = (H/2)^2 / H^2 = 1/4. The 15m layer is 2.5 times thicker than 6m, so time increases by 2.5^2 = 6.25. The question asks for the comparison of drainage types, which is always 4 times.

Multiple choice

A 10 m thick clay layer is underlain by a sand layer of 20 m depth (see figure below). The water table is 5 m below the surface of the clay layer. The soil above the water table is capillary saturated. The value of gsat is 19 kN/m3. The unit weight of water is gw. If now the water table rises to the surface, the effective stress at a point P on the interface will
  1. increase by 5$\gamma w$

  2. remain unchanged

  3. decrease by 5 gw

  4. decrease by 10 gw
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 $\text{Effective stress = total stress - pore water pressure}\\ \text{We know that rise of water due to capillary action acts as s surcharge for the calculation of effective pressure. So, when the water table rises upto ground level surcharged will be zero and reduction of the effective stress will be equal to $5 \gamma_w$ so reduced by $5 \gamma _w.$}$

Multiple choice

The vertical hydraulic conductivity of the top soil at certain is 0.2 cm/hr. A storm of intensity 0.5 cm/hr occurs over the soil for an indefinite period. Assuming the surface drainage to be adequate, the infiltration rate after the storm has lasted for a very long time, shall be

  1. smaller than 0.2 cm/hr

  2. 0.2 cm/hr

  3. between 0.2 and 0.5 cm/hr

  4. 0.5 cm/hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 Since, the surface drainage is adequate. So, infiltration capacity will be equal to the vertical hydraulic conductivity of the soil as 0.2 cm/h.

Multiple choice

The moisture content of soil in the root zone of an agricultural crop at a certain stage is found to be 0.05. The field capacity of the soil is 0.15. The root zone depth is 1.1 m. The consumptive use of crop at this stage is 2.5 mm/day and there is no precipitation during this period. Irrigation efficiency is 65%. It is intended to raise the moisture content to the field capacity in 8 days through irrigation. The necessary depth of irrigation is

  1. 115 mm

  2. 169 mm

  3. 200 mm

  4. 285 mm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation