Experimental study on static and cyclic liquefaction of cohesionless chang dam soil

Liquefaction characteristics of cohesionless Chang dam soil under monotonic and cyclic loading conditions are studied. Unlike previous studies where soil explored is mostly standard loose silty-sand, the current study focuses on naturally occurring medium dense silty-sand. An attempt has been made to link the conditions defining the experimentally observed static and cyclic liquefaction. Large excess pore water pressure of similar magnitude was observed under both the monotonic and cyclic loading conditions. Effective stress paths (ESPs) continuously descended and reached stress origin indicating the state of liquefaction: static and cyclic. Instability line (IL) showed initiation of static liquefaction under monotonic compression loading and any stress state above IL was unconditionally unstable under undrained boundary conditions. On reaching IL, ESPs under cyclic loading continued to move along it indicating a similar mechanism for both the static and cyclic liquefaction. Instability line determined from monotonic loading acted as a trigger for both the static and cyclic liquefaction and, any stress state above it was unstable under both the loading conditions.