EFFECT OF CNS LAYER ON THE BEHAVIOUR OF UNDERLYING EXPANSIVE SOIL MEDIA--AN EXPERIMENTAL STUDY

Certain studies indicated that a cohesive non-swelling soil (cns) layer may prove to be effective in resisting the swelling and swelling pressure of underlying expansive soil. An attempt is made to evaluate the effect of various thicknesses of cns layer on swelling and related characteristics of underlying expansive soil media. Experiments have been conducted in a large scale test in which different thicknesses of cns layer were placed on an expansive soil mass compacted at known initial density and moisture content under controlled conditions. The soils were subjected to saturation during which alterations in swelling and swelling pressure were recorded. The variation of density, moisture content and shear strength of the soils with depth were observed. The large scale experimental study indicated that the cns layer has considerable effect on density, lateral swelling pressure and shear strength of underlying expansive soil with depth and also on "no volume change" depth. The analysis of the result is carried out in the light of an idealized, anisotropic micro-particle and micro-anchor approach. (Author/TRRL)