高速远程地震黄土滑坡发生机制试验研究

1920年海原大地震触发了多处典型高速远程地震黄土滑坡，本文在对西吉党家岔滑坡进行野外调研的基础上，采集了具有代表性的滑带土作为试验样品，以1940年5月18日美国帝国谷强震记录作为波动输入，利用DPRI环剪试验机，对该滑坡的发生机制进行了一系列环剪试验研究。结果表明，地震发生时，坡体潜在滑面的滑带土在强震作用下发生的滑动面液化（Sliding surface liquefaction）现象是导致高速远程滑坡形成的一个重要因素。伴随着滑动面液化过程，滑体产生了逐渐增大的剪切位移及孔隙水压力（地震力作用结束瞬间已分别达到2.03m及104kPa），并获得了较大的速度，为高速远程滑坡的发生提供了条件。

AN EXPERIMENTAL STUDY ON THE INITIATION MECHANISM OF RAPID AND LONG RUN-OUT LOESS LANDSLIDE CAUSED BY 1920 HAIYUAN EARTHQUAKE

The 1920 Haiyuan Earthquake caused a great number of loess landslides, and resulted in more than 100,000 deaths. This paper investigates the Dangjiacha landslide, a typical rapid and long run-out landslide located in Xiji County triggered by Haiyuan earthquake. Representative soils on sliding surface were collected for soil tests. By using the advanced DPRI ring shear apparatus, a series of ring shear tests were carried out to study the initiation mechanism of Dangjiacha landslide under the seismic wave loading of EL-Centro Earthquake. This Earthquake occurred on May 18, 1940 in United States. The ring shear test results show that when the earthquake happened, the sliding surface liquefaction occurred on potential sliding surface of landslide. It was an important reason for taking place of rapid and long run-out landslide. Meanwhile, a large shear displacement (2.03 m) and a high pore water pressure (104 kPa) could be generated and a high velocity could be got for the sliding mass, which supplied a necessary condition for the generation of rapid and long run-out landslide.