Measurement of Lateral Earth Pressures on an Embedded Foundation During Earthquakes

The dynamic earth pressures during earthquakes have been observed on both sides of an embedded foundation for about 30 events. Some characteristics of dynamic earth pressures were extracted from the observations. The main findings obtained in this study can be summarized as follows. (1) The phase characteristics of earth pressures between both sides of the foundation show remarkable dependence on the frequency components of acceleration motions. (2) The earth pressures on lateral sides of the foundation are strongly related with horizontal velocity motions of the foundation. (3) The peak values of earth pressures have shown a tendency to increase with increase of lower frequencies contained in accelerograms on the ground surface. (4) The fact that the earth pressure has strong relation with the velocity motions of the foundation may be roughly explained by means of a simplified one-dimensional wave propagation theory for a soil rod model.