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

Two soil specimens with identical geometric dimensions were subjected to falling head permeability tests in the laboratory under identical conditions. The fall of water head was measured after an identical time interval. The ratio of initial to final water heads for the test involving the first specimen was 1.25. If the coefficient of permeability of the second specimen is 5 times that of the first, the ratio of initial to final water heads in the test involving the second specimen is

  1. 3.05

  2. 3.80

  3. 4.00

  4. 6.25
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a falling head test, k is proportional to ln(h1/h2). Since k2 = 5 * k1, then ln(h1/h2)_2 = 5 * ln(h1/h2)_1. ln(h1/h2)_2 = 5 * ln(1.25) = 5 * 0.223 = 1.115. h1/h2 = e^1.115 = 3.05.

Multiple choice

A layer of normally consolidated saturated silty clay of 1 m thickness is subjected to one dimensional consolidated under a pressure increment of 20 kPa. The properties of the soil are: specific gravity = 2.7, natural moisture content = 45%, compression index = 0.45, and recompression index = 0.05. The initial average effective stress within the layer is 100 KPa. Assuming Terzaghi's theory to be applicable, the primary consolidation settlement (rounded off to the nearest mm) is

  1. 2 mm

  2. 9 mm

  3. 14 mm

  4. 16 mm
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice

Steady state seepage is taking place through a soil element at Q, 2 m below the ground surface immediately downstream of the toe of an earthen dam as shown in the sketch. The water level in a piezometer installed at P, 500 mm above Q, is 100 mm above the ground surface. The bulk saturated unit weight of the soil is 18 kN/m3 and the unit weight of water is 9.81 k N/m3. The vertical effective stress (in KPa) at Q is

  1. 14.42

  2. 15.89

  3. 16.38

  4. 18.34
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice

The flow net around a sheet pile wall is shown in the sketch. The properties of the soil are: permeability coefficient = 0.09 m/day (isotropic), specific gravity = 2.70 and void ratio = 0.85. The sheet pile wall and the bottom of the soil are impermeable. The factor of safety against the occurrence of piping failure is

  1. 3.55

  2. 2.93

  3. 2.60

  4. 0.39
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The factor of safety against piping is the ratio of critical hydraulic gradient (ic) to the exit gradient (ie). ic = (G-1)/(1+e) = (2.7-1)/(1+0.85) = 0.919. The exit gradient ie = delta_h / (nf * l), where delta_h is head loss and l is length of the last flow element. Based on the flow net, calculating the ratio yields approximately 2.60.

Multiple choice

Wheat crop requires 55 cm of water during 120 days of base period. The total rainfall during this period is 100 mm. Assume the irrigation efficiency to be 60%. The area (in ha) of the land which can be irrigated with a canal flow of 0.01 m3/s is

  1. 13.82

  2. 18.85

  3. 23.04

  4. 230.40
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Delta = 55 cm = 0.55 m. Base period B = 120 days. Duty D = 8.64 * B / Delta = 8.64 * 120 / 0.55 = 1885 ha/cumec. Area = Flow * Duty = 0.01 * 1885 = 18.85 ha. Adjusting for 60% efficiency: 18.85 * 0.6 = 11.31. Re-calculating with effective depth yields 13.82.

Multiple choice

The flow net around a sheet pile wall is shown in the sketch. The properties of the soil are: permeability coefficient = 0.09 m/day (isotropic), specific gravity = 2.70 and void ratio = 0.85. The sheet pile wall and the bottom of the soil are impermeable. The seepage loss (in m3 per day per unit length of the wall) of water is

  1. 0.33

  2. 0.38

  3. 0.43

  4. 0.54
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Seepage loss q = k * H * (Nf / Nd). From the flow net, Nf = 4 and Nd = 9. k = 0.09 m/day. Assuming H is the head difference, calculate q.

Multiple choice

In Marshall testing of bituminous mixes, as the bitumen content increases, the flow value

  1. remains constant

  2. decreases first and then increases

  3. increases monotonically

  4. increases first and then decreases
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the Marshall test, the flow value represents the deformation of the specimen at failure. As bitumen content increases, the mix becomes more plastic and deformable, leading to a monotonic increase in flow value.

Multiple choice

A singly under-reamed, 8-m long, RCC pile (shown in the adjoining figure) weighing 20 kN with 350 mm shaft diameter and 750 mm under-ream diameter is installed within stiff, saturated silty clay (undrained shear strength is 50 kPa, adhesion factor is 0.3 and the applicable bearing capacity factor is 9.0 to counteract the impact of soil swelling on a structure constructed above. Neglecting suction and the contribution of the under-ream to the adhesive shaft capacity, what would be the estimated ultimate tensile capacity (rounded off to the nearest integer value of kN) of the pile?

  1. 132 kN

  2. 156 kN

  3. 287 kN

  4. 301 kN
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation