Pore Water Pressures Measured in Sand Deposits During an Earthquake

Abstract

A set of piezometers was embedded in sand deposits on a reclaimed island in Tokyo Bay and a seismograph was placed on the ground surface nearby in order to monitor simultaneously in-situ pore water pressures and horizontal accelerations during earthquakes. During the September 25, 1980 earthquake, the instruments registered increases in pore water pressures corresponding to 19% and 16% of the effective overburden pressure at depths of 6.0 M and 14.0 M, respectively. At the same time, a maximum horizontal acceleration of 95 gal was registered at the ground surface. Laboratory cyclic triaxial tests had been performed on undisturbed soil specimens obtained from this site using a large diameter sampler. Based on the laboratory test data, an estimate was made of the pore water pressures that might be produced in the deposit by seismic shaking of a maximum acceleration of 95 gal. The estimated values of pore water pressure were shown to be in good agreement with the pore water pressures registered during the earthquake. (Author/TRRL)