The Mechanisms And Simulation Of The Rapid Long Run-out Loess Landslide

Loess landslide is the most catastrophic geohazard in the loess area of China.Rapid longrun-out slide is characterized by a very high speed and long moving distance，so this type ofloess landslide impairs economy and security of mankind seriously. Carrying on the researchof the mechanisms and motion of rapid long run-out slide is significant to prediction andprevention of this geohazard.The distribution of Rapid long run-out slide is ascertained through field investigations.This paper takes Dapuzi loess landslide and Dongfeng loess landslide of the loess platform tothe south bank of the Jinghe River as typical Rapid long run-out slide analysis cases. Basicdata for modeling is obtained by measuring topography. the parameters such as shearingresistance τ、shearing resistance of sliding steady state τss、effective friction coefficient ofsliding、initial apparent friction ect. for the simulations are gained by routine test of soil、tri-axial test and ring shear test. Revealing the trigger mechanisms and the process ofmovement by simulating and Analyzing two-dimensional simulation based on finite elementmethod and three-dimensional simulation based on Sassa’s method.The results show that，the original slope surface of Rapid long run-out slide is high andsteep，which provides a high-speed at initial stage；The peak strength of Q2loess which is themaximum thickness of the soil is high but the shearing resistance discount remarkably afterthe peak，which is the important reason that lead to the high-speed lasted of the slide mass andthe slide mass moves a long distance；Rapid long run-out slide often occurs on the sides ofloess platforms near rivers，the sliding mass slumps down rapidly hits on the terrace，porewater pressure increased，effective normal stress reduced，shearing resistance discounts，so thesliding mass could achieve a high acceleration and get to a long distance with a high-speed；And the slide mass lead to liquefaction of the saturated gravels，In areas with high claycontent，mud layer would appear on the sliding surface，the friction of the mud layer is verylow，which lead to the slide mass move a long way；Meanwhile，the simulations of the rapid long run-out slide demonstrates the process of the development and the movement of thelandslide directly，the results of the simulations are coincident with the characters of rapidlong run-out slide.