BUILD-UP AND DISSIPATION OF EXCESS PORE WATER PRESSURE IN SATURATED SAND UNDER IMPACT LOADING
冲击载荷下饱和砂土中超孔隙水压力的建立与消散过程

The shock pressure on saturated sand in a cylinder induced by impact loading is measured. The relation between the amplitude of the shock pressure and the drop-height is analyzed in terms of dimensional analysis. The whole build-up and dissipation process of excess pore water pressure is also measured. The experimental result shows that the mechanism of the build-up of excess pore water pressure induced by impact loading is the same as that induced by cycling loading. Only the increasing ratios and amplitudes of the loadings are different. The maximum value of excess pore water pressure at one point in the sand column is equal to the overburden pressure of the corresponding position. The critical intensity value of mono-impact which may cause the saturated sand to be liquefied completely is obtained. The influence of multi-impacts on the build-up of excess pore water pressure is analyzed. For the dissipation of excess pore water pressure,the experimental results show that the higher the drop-height is,the longer the dissipating time is.