Question

When a dam is built of impervious compressible soil, water is entrapped in the pore space due to ___________

(a) Excessive pore pressure

(b) Volume change in the soil mass

(c) Low shear strength of soil

(d) Unstable soil mass

The question was asked in homework.

My doubt stems from The Swedish Slip Circle Method in portion Stability of Slopes of Geotechnical Engineering II

Answer 1

Correct answer is (b) Volume change in the soil mass

The explanation: When a dam is built of relatively impervious compressible soil, excess pore pressure develops in the air and water entrapped in the pore pressure. This is because the soil mass undergoes a change in the soil due to compaction of the dam construction and also due to a down weight.