SAND LIQUEFACTION DUE TO IRREGULAR EXCITATION

An electro hydraulic servo type loading system was incorporated into the conventional triaxial shear test apparatus so that any desired form of load pattern can be applied to soil specimens. In applying this system to the study of liquefaction of saturated sands, a difficulty was encountered in keeping the applied stress perfectly controlled even after the rigidity of the sample falls considerably due to the onset of liquefaction. The use of an elastic joint in the loading ram proved very useful to overcome this defect. The acceleration records obtained at the time of the Niigata earthquake of 1964 were used as input load patterns to be applied to saturated specimens of a Niigata sand. The investigation disclosed several features of interest concerning the behaviors of the sand when subjected to irregular exitation.