| Guizhou province is located in the southwest of our country，where geologicaldisasters have the characteristics of "many points and widely distributed, varioustypes,suddenly happen,and heavy disaster losses".Among the disasters, the hard andsoft rocks alternated structure of slope,in which the soft layers are mainly composedof mud shale and shale and the hard layers are mainly composed of limestone, is atypical kind of slope structure in Guizhou province.This article relies on the scientificresearch project "Geological disaster monitoring and early warning and research ondecision support platform”,carried on field geological survey work of the landslidethree times,on the basis of full investigation the basical geological conditions, theauthor studies the landslide by qualitative analytical method and quantitative analysismethod, including numerical simulation and physical simulation, and makes apreliminary analysis of the sensitivity influencial factors of the landslide and stabilityanalysis and evaluation of the landslide at last.The main work and results were asfollows:(1) The deformation and failure phenomena of the landslide are recorded,settledand analyzed detailedly.On this basis, according to the deformation and failurecharacteristics of the landslide and deposit characteristics,study area can be dividedinto1#landslide,2#and3#landslide, and the1#landslide can be divided into thewhole sliding zone (A) from the centre to the back of the landslide, relative completearea (B) in the middle and accumulation area (C) from the middle to the forepart again.Based on the geological prototype of Xiang Shuping landslide, establish a "conceptualmodel" of the landslide.(2) The quasi three dimensional calculation model was established by FLAC3Dsoftware, and making a numerical simulation research on formation mechanism ofXiang Shuping landslide. Simulating the initial stress field distribution characteristicsfirst,and then the aging deformation evolution stage of high valley slope andformation evolution stage of Xiang Shuping landslide.Simulation results reflect thatduring the formating process of the valley,the slope rebounds due to unloading andmakes a creep deformation,making aging deformations in the middle to lower part ofthe slope,developing LC6#trough and LC3#trough gradually,which affects thestability of landslide area further.Xiang Shuping landslide is in the aging deformationstage,and the occurrence of landslide is due to the LC6#trough located in the hardand soft rocks alternated structure of slope near the bottom pulled open first, then tracting LC3#trough above pulled open gradually and eventually causing theoccurrence of Xiang Shuping landslide.(3) By using the method of bottom friction experiment,one of the physicalsimulations,carrying on a research on formation mechanism of Xiang Shupinglandslide again.Experimental phenomenon shows that the trough located near thebottom of the slope surface in the hard and soft rocks alternated structure of slopepulled open first and then split gradually, and drawing the trough above in thecorresponding location slowly and expand gradually, finally causing a crack at theback edge of Xiang Shuping landslide,showing a trend to expanding continully. Theexperiment recreates the deformation and failure process of Xiang Shuping landslide,and the formation mechanism is analyzed.On the basis of physical simulation study,carrying on a preliminary sensitivity analysis on the main influencial factor,relativethickness of the hard and soft rock strata.Analysis shows that the relative thickness ofthe hard and soft rock strata make great affluence on stability and deformation andfailure process.(4) Making a stability calculation of the landslide and calculation results showthat under natural condition, Xiang Shuping landslide are stable, and under heavy raincondition, due to the body of landslide filled fully with water,slope stabilitycoefficient has a great decrease.The landslide is basically stable or unstable,thereexists a possibility that the landslide will slide again.Setting intercepting drain at thereasonable position around the landslide to reduce the risk of more deformation andfailure of slope is suggested.(5) Making a comprehensive study on the formation mechanism of thelandslide,and Xiang Shuping landslide is a typical landslide,whose geological basis isthe geological structure composed by soft rock layers, which are mainly mud shaleand shale and hard rock layers,which are mainly limestone, alternatively.Its geologicalmechanics model of deformation and failure is creep-cracking type of pull-typelandslide. |
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