Time Dependency

Abstract

Time-dependent deformation in soil mechanics is expressed mainly in terms of hydrodynamic time lag, or consolidation. The concept is described elegantly and intuitively by Lambe and Whitman (1979) who say that the time, t, required for consolidation should be:

• (a) directly proportional to the volume of water squeezed out of the soil, which will in turn be directly proportional to the product of the change in confining pressure (▵σ), the compressibility of the soil matrix (C) and the thickness, of the soil mass (H) equivalent in one-dimensional terms to the volume;

• (b) inversely proportional to the rate at which the water can flow through the soil, which will be given by Darcy’s law v = ki = k ▵σ/H where k is the permeability coefficient and i the hydraulic gradient.