Deterioration processes in hard clays and clay shales

Soil deterioration is one of the main causes of slope failure in hard clays and clay shales, but so far a clear general framework of the causes of deterioration is still missing. Based on laboratory data, field observations and speculation, this paper examines some processes of deterioration of stiff overconsolidated clays and clay shales with particular regard to their influence on the stability of slopes. In particular, deterioration localized within soil bands or involving large soil masses is described with reference to its mechanical or physico-chemical causes. Coupling between mechanical and physico-chemical processes is considered.