On the Amplitude of Earth Pressure of Cohesive Soil

After Mononobe and Okabe proposed a formula to compute a seismic earth pressure, some studies on a seismic earth pressure of sandy soil have been made. On the contrary, the study on a seismic earth pressure of cohesive soil is few. But in view of following fact, it is necessary to clarify the seismic earth pressure of cohesive soil. That is, there is no established method for the calculation of a seismic earth pressure of cohesive soil during an earthquake. As a basic investigation on a seismic earth pressure of cohesive soil, the authors conducted the vibrating experiments using a shaking table. They are performed on a nearly saturated Ube clay which was consolidated in a shaking box with fixed wall or movable wall. Main conclusions are as follows : (1) The distribution of amplitude of earth pressure is depended on the distribution of water content in a soil layer. (2) At the rotational angle of wall θ (=y/h)=5.0×(10)^<-5> rad, the amplitude of earth pressure is inverse triangle pattern which upper earth pressure is larger than lower earth pressure, but, at θ=1.0×(10)^<-3> rad it changes to triangle pattern which middle one is largest. where, y and h are the displacement and height of wall, respectively. (3) The effect of a surcharge on the resultant force of amplitude of earth pressure acting on fixed wall becomes notably large when l/H_0 is about 0.7. where, l : distance from the wall to the center of the position of surcharge on soil layer, H_0 : thickness of soil layer.