AN EXPERIMENTAL STUDY OF DYNAMIC EARTH PRESSURES

Abstract

An experimental study has been conducted to investigate the pressure exerted on a rigid and imnLoveable retaining wall during earthquakes. A steel sheet of size 100 cm x 65 cm x 1.65 cm was used as rigid retaining wall. This sheet was put in a 200 cm x 100 cm x 75 cm size tank and backf illed on one side with dry, dense cohesionless sand. The tank was vibrated, with the help of motor and oscillator fitted at its bottom with different forces of excitation. The six small size pressure cells, designed and.fabricsted fo r the purpose, were embeded in the retaining well (iron sheet) to measure soil pressures with the help of pen recording arrangement. An acceleration pickup was placed on the top or~the retaining wall to measure the accelerat-ion of the well. Three initial conditions namely at rest, active and passive were carried out for increasing dynamic forces which gave horizontal acceleration pto 2.0g. The result of experiment for the three cases have been plotted as, 1. Pressure versus seismic coefficient for each cell, 2. Pressure distribution along the depth of the wall for different seismic coefficient values, and 3. Total pressure versus seismic coefficient.. These plots indicate that the pressure distribution and magnitude of the total (static plus dynamic) pressure do depends on the initial (static) condition of the wall