THE STRUCTURAL CHARACTERISTIC AND THE STABILITY ANALYSIS OF MAHE COLLAPSE BODY

This paper mainly researches the structural characteristic and the stability analysis of Mahe collapse body.First of all,the range of slope and changing shape in landscape orientation restraint the application of drilling exploration.It is difficult to figure out the loose coverage thickness,fluctuating bedrock beneath and situation of developing weathered layer exactly.Hence,this paper adopts SSP(Seismic Scatter Profile)method to explore the structural characteristic of Mahe collapse body.Furthermore,this paper evaluates the stability of Mahe collapse body under three conditions(natural condition、earthquake condition and rainfall condition)by using various LEM(Bishop、Janbu、Morgenstern-Price)and then calculating and comparing the safety factors of discontinuity between bedrock and coverage.Finally,this paper concludes that the geological structure of Mahe collapse body is approximately sorted into three layers.The upper layer close to surface is loose coverage with a thickness about 30~40mm,not cementitious; The medium layer is a medium to strong weathered layer with a thickness about 10~15mm,weathered strongly,fractured intensively; The bottom layer is a relatively intact rock mass under 40~50m depth with a wave velocity above 2500m s-1; As to stability evaluation,there are two unstable conditions:the collapse body may occur failure along the bottom boundary of coverage or weathered layer under earthquake condition,while the collapse body may also occur failure along the bottom boundary of weathered layer under rainfall condition.