Strength of clay subjected to cyclic loading

A survey is presented of published data and data from private files concerning the effect of cyclic loading on the strength of clay soil. All clays develop significant cyclic strains under pulsating stresses, and the strength after cyclic loading is less than the normal static undrained strength. Reversing cyclic stress is more detrimental than one directional cyclic stress. This cyclic deterioration appears to be a strain dependent process whereby cyclic strains develop large excess pore pressures that in turn lead to softer and weaker soil.