AN EXPERIMENTAL STUDY ON THE MECHANISM OF RAPID AND LONG RUN-OUT LANDSLIDE TRIGGERED BY WENCHUAN EARTHQUAKE

The 2008 great Wenchuan earthquake caused multiple rapid and long run-out landslides,which resulted in a lot of deaths and property loss.Donghekou landslide,a typical rapid and long run-out landslide triggered by Wenchuan earthquake,is located in Qingchuan county,and at present,it is concerned and discussed particularly because of its complex original mechanism.Field investigations show that the original mechanisms and dynamic features mainly include the followings,for example,the shattering collapse,the horizontal slinging,the debris flow and the vibration liquefaction,etc.In order to simulate and reconstruct the vibration liquefaction,representative soils on sliding zone of Donghekou landslide were collected for soil tests.By using the advanced DPRI ring shear apparatus,a series of ring shear tests have been carried out to study the vibration liquefaction process of Donghekou landslide under the loading of real seismic waves,and some ideal results were gotten.The test results show that when the earthquake happened,the vibration liquefaction occurring on the potential sliding surface played an important role in generating the rapid and long run-out landslide.When the soils were dry,only a small displacement(0.007m)was generated,which couldn't form a landslide with high speed and long run-out;with the vibration liquefaction,the shear strength could be decreased and a large displacement could be generated,which supplied a necessary condition for the generation of rapid and long run-out landslide.