Test: Compressibility & Consolidation - 2 - Civil Engineering (CE) MCQ

coefficient of consolidation

using 1 for sand and 2 forclay

As the thickness of both layer is same, so for same degree of consolidation:

For single drainage,

For double drainage,

⇒ or, T₂ = t₁/4

Coefficient consolidation

T_v is constant and unit less d is drainage path, unit is centimeter (cm) t is time of consolidation , unit is sec.
∴ unit of C_v = cm²/ sec

Only excess pore pressure completely dissipates and effective stresses increase

ultimate consolidation settlement is given by,

so as initial void ration e₀ , increase ultimate settlement  decrease.

These are two equations for calculating the total settlement. The coefficient of volume compressibility (m_v) depends up on the stress range and therefore not a constant. However compression index (C_c) is constant for a normally consolidated clay.

Additional settlement
= ΔH₂ = ΔH₁ = 25 mm

Curve fitting methods like (1) square-root of time method and (2) logarithm of time method are used to determine coefficient of consolidation. The curve between dial gauge reading and time t obtained in the laboratory by testing the soil sample is similar in shape to the theoretical curve between U and T_v obtained from the consolidation theory. This similarity between the laboratory curve and the theoretical curve is used for the determination of the coefficient of consolidation (C_v) of the soil.

For