Mechanism Of Pore Pressure Generation Due ToThe Different Direction Of Earthquake AccelerationOn Saturated Soil

Abstract

Slope stability analysis during earthquake earned out in terms of effective stress require an accurate measurement of pore-pressure along the shear /one. Due to the rapid stress changes, during an earthquake, undramed cyclic loading is given to the saturated soil layers in slopes. For reproducing the stress condition in slopes during earthquakes, a cyclic loading ring shear apparatus had been developed in Kyoto University, Japan. The shear box of this apparatus has been improved for the tests under undramed state and for monitoring the generation of pore pressure during shear. In order to examine the influence of seismic loading direction, two conditions in which either the seismic stress is given in an almost hon/.ontal direction or in an almost vertical direction was reproduced in the apparatus. The test results showed that, in saturated soils, it is not possible to estimate the seismic coefficient necessary to cause failure from the initial stress and the effective dynamic friction angle if the mechanism of pore pressure generation is not considered. This is attributed to the variation in pore-pressure generation depending on the seismic loading directions. Transactions on the Built Environment vol 20, © 1996 WIT Press, www.witpress.com, ISSN 1743-3509 124 Earthquake Resistant Engineering Structures