Application Of Strength Reduction Technique To The Three-dimensional Stability Analysis Of Landslides

Landslideis ageological process inwhichamass ofrock,debris orearth moves downa slope along a soft surface or a soft belt. China is one of the countries prone to landslidehazards.WiththeimplementationoftheNational StrategyofWestDevelopment,landslidesconstitute one of the key geological problems in the construction of infrastructures. Solandslidestabilityresearchisimportantfortheexecutionofthestrategy.In the dissertation, the state of art development of methods is firstly reviewed forlandslide stabilityevaluation, and then feasibility study is carried out for the application ofstrength reduction technique (SRT) to the three-dimensional stability evaluation oflandslidesbasedonFLAC3Dcode.Majorresultsaresummarizedasfollows.(1) SRT can be used for the three-dimensional stability evaluation of landslides withknownslipsurfaces,andtheslipsurfacecanbemodeledbysolidelements.(2) Displacement convergence criterion of given nodes is objective in the selection of thenodes and their turning points in convergence curves, so it's suggested that therun-throughcriterionofyieldzonesbeusedwhereverpossible.(3) Compared with limit equilibrium method (LEM), SRT considers the constitutiverelation, so except for the factor of safety (Fs), it can further simulate the possibleslidingdirectionsandlocalstabilityofaslide.(4) For the application of SRT to particular landslides, the modeled factor of safety andsliding directions are a little different from those by three-dimensional LEM, howevertheresultsarestillcomparable.Undernaturalstate(noearthquakeeffectisconsidered),for Siwancun landslide of Luding Hydropower Station, the obtained Fs is quite closerespectively by 3D SRT and by 3D LEM, i.e.1.49 and 1.42, however the modeledsliding direction is a little different, SW89.7ofor SRT and SW80ofor LEM. ForMoluocun landslide of Houziyan Hydropower Station, the obtained Fs is 0.955 and1.115respectivelyby3DSRTandby3DLEM,thedifferenceisalittlebigger,howeverthe modeled sliding direction is basically the same, SW60ofor SRT and SW61oforLEM.(5) Forthestabilityevaluationoflandslideswithoutdefinitetipatthetoe,SRTcanbeusedtosearchit out.The majordeformingzoneis quiteclose tothat confinedbythecriticalsurfaceof2DLEM.(6) SRT is much more sensitive to seismic effects than LEM. Fs is greatly reduced underearthquakeconditions.Finally, further researches are suggested for SRT, i.e. search of critical surface,techniqueforthesimulationofearthquakesandtransientseepage.