| The hydraulic project of theThree Gorges of the Yangtze River is magnificent all over the world.It has the function of controlling the flood,reducing the disaster,curing the environment,storing the water for generating electricity and developing the economy.So the construction of the Three Gorges Project is a great decision of benefiting the people of the time.After the Project is completed,the water level of the reservoir area will be raised more than 100 meters.Furthermore,because of the needs of the flood controlling,the water level of the reservoir will fluctuate periodically in the range of 175m-145m-175m every year after the operation of Three Gorges reserveoir.This will cause the big changes of the groundwater system of the reservoir bank and the deterioration of the physical and mechanical properties of the rock and soil and inevitably lead to trigger and aggravate the geological hazards along the reservoir bank,including collapses,landslides,debris-flows,reservoir bank collapses and rebuilding et al.This paper is depended on one of the emergency rescue implementation projects of the phaseâ…¢geological disasters prevention project-Dianchang landsile prevention project in Xinshan County of Hubei Province.Based on field investigation and data collection,the author makes use of the limit equilibrium method(transfer coefficient method) and numerical simulation method(FLAC) systematically to study and forcast the landslide stability under the 7 work conditions of water level rise,drawdown slowly(0.186m/d) and drawdown speedly(3m/d).Then according to the results of stability analysis,the author does further study on the landslide prevention and treatment.Through studying,the following achievements are obtained:(1) Dianchang landslide is a medium-sized loose talus slide,which develops along the rockbasis.Under natural situation,the landsile is in basic stable state and no macroscopic deformation signs are found.The mode of deformation and failure is traction sliding failure. (2) The safety factors calculated by the transfer coefficient method and the finite difference method(FLAC codes) are very close.The maximum error is about 5%.And the change trends of the stability under the water level fluctuation states they reflected are consistent:under the conditions of the water level rise,the higher the water level,the worse the stability;under the condions of water landing,the water level drop greater,deceleration sooner,the stability becomes worse;under water landing process,the stability is not always reduced.Because the underwater landslide area is reduced and the hydraulic gradient is smaller,it is conducive to the stability of the landslide;under the 7th condition of water level droping sharply,the whole failure of Dianchang landslide will happen.(3) FLAC simulation results of Dianchang landslide stability indicate:the landslide body has obvious iniative segment,passive segment and anti-slide segment.Under the limit equilibrium state of these 7 calculation conditions,the central sliding body dragging the rear part slides from the altitude of near 170 meter along the rockbasis.(4) The research of the prevention and treatment schemes shows that 'surface drainage ditch+retaining wall+anti-slide pile' is an effective scheme and it can prevent the landslide from having a greater displacement and maintain the safety operations of the NO.312 highway and then can achieve the purpose of radical curement of the Dianchang landslide.
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