15 questions. Tap an option to check it instantly, then read the solution.
Question 16Easy
______ condition develops in a saturated thick layer of loose fine sandy soil when disturbed by vibration from pile driving in an adjoining area or by the pressure of flowing water.
When effective stress in saturated loose fine sand drops to zero (by vibration-induced pore pressure or upward seepage), the sand loses all strength: quick sand condition.
Question 17Easy
The void ratio for which the change of volume remains constant (zero) during shearing is called the:
The vane shear test is the in-situ test for the undrained strength of soft saturated clay.
Question 21Medium
A shear box test was performed to give the following results for a cohesive soil sample: Test 1 — normal stress 150 kN/m², shear stress at failure 110 kN/m²; Test 2 — normal stress 250 kN/m², shear stress at failure 120 kN/m². The values of c and tan φ are:
In a triaxial test, the cell pressure is increased from 0.1 N/m² to 0.26 N/m² and the pore water pressure from 0.07 N/m² to 0.15 N/m². Skempton's pore pressure parameter is given by:
Calculate the shear strength in terms of effective stress on a plane within a saturated soil mass at a point where the total normal stress is 295 kPa and the pore water pressure is 120 kPa, when c′ = 12 kPa and the angle of internal friction is 30°. (Take tan 30° = 0.578.)
Which of the following statements are true about quicksand? i. It is only a condition but not a type of sand. ii. It is a condition and a type of sand too. iii. Quick sand condition is reached when the critical hydraulic gradient is approximately equal to unity. iv. Quicksand condition occurs more commonly in coarse grained sand or gravels than in fine sand.
Quicksand is a condition, not a type of sand (i true, ii false). It occurs when the upward gradient reaches ic ≈ 1 (iii true). It is more common in fine sands than in coarse sands or gravels (iv false).
Question 25Medium
The unconfined strengths of three types of cohesive soils, Soil A, Soil B and Soil C, are 35 kN/m², 450 kN/m² and 140 kN/m² respectively. Identify the correct statement based on the consistency behaviour of soils.
Answer: B. It disregards the effect of the forces acting on the sides of the individual slices
Bishop's simplified method neglects the interslice (side) shear forces, which is the accepted answer (b).
Question 29Easy
Match the type of test (List 1) with the objective of the test (List 2). List 1: A — Standard penetration test, B — Hydrometer test, C — Proctor test, D — Vane test. List 2: 1 — Grain size analysis, 2 — Shear strength, 3 — Bearing capacity, 4 — Compaction.
In stress distribution in soil, the approximate method in which the vertical stress at any point due to any loaded area is calculated by dividing the area into small parts is:
The equivalent point load method divides the loaded area into small units, replaces each by a point load at its centroid and sums the Boussinesq stresses.