冲击载荷下饱和砂土中超孔隙水压力的建立与消散过程

对落锤冲击造成饱和砂土中的冲击压力进行了测量。通过测量得到了冲击时饱和砂土中超孔隙水压力的建立和消散过程。分析了多次冲击对超孔隙水压力建立的影响。得到了一次冲击就能使饱和砂土达到完全液化的冲击强度临界值．

BUILD-UP AND DISSIPATION OF EXCESS PORE WATER PRESSURE IN SATURATED SAND UNDER IMPACT LOADING

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.