The Mechanism Of Landslide Influenced By Rainfall And Reservoir Water Level Fluctuation And Renewed Criterion Research In Three-gorges Reservoir

After the Three Gorges Project of the Changjiang River is built and The Three Gorges reservoir operations normally, The water level of The Three Gorges reservoir will periodically fluctuate between 145 and 175 m.This leads to the slide body which landslides hazard happened frequently because of abundant rainfall and geological environment posibility of revival rise significantly. Once the landslide revivals because of the water level of The Three Gorges reservoir change and rainfall, which will cause tremendous losses in the lives and properties of the people in affected areas.As a result, we should in view of actual conditions of the Landslide in reservoir of the Three Gorge Projects, analyse the landslide's revival mechanism under the water level of The Three Gorges reservoir and rainfall, and then determines the cirteria for forecasting of landslide, in order to provide a basis for the cirteria for forecasting of landslide in Three Gorges reservoir and landslides hazard study.The object of the thesis are 585 grave and revival landslides which volume greater than 100m3 in Three Gorges reservoir.It is difficulty to fix the revival situation because of complicated operation condition and the number of research objects.In thesis has carried out research work as follows four aspects:①Analysis landslides revival inducing factors.②Establish the classification of landslide, basing on revival inducing factors.③In view of different kinds of landslides, through the numerical simulation, reveals that landslide under the revival inducing factors seepage fields and features of deformation; Concrete content, method and results of the study as follows:1) Through the analyses on landslides main inducing factors in reservoir, fix that the water level of reservoir fluctuate and rainfall are main factors.The influences of landslides are embodied in softening action of water, reducing weight and the action of hydrodynamic pressure.2) Through the analysis of the current method of landslides classification, based on the different mechanism by softening action of water, reducing weight and the action of hydrodynamic pressure. Made the method of landslides classification based on inducing factors, divided the landslides into three groups: reducing weight mode, hydrodynamic pressure mode and mixed mode.3) Based on the inducing factors divided the landslides into three groups, transaction of SunJiazhuang landslide, BaZimen landslide and baijiabao landslide are chosen as sample of landslides in reservoir, using the Computational Method which are fluid-solid coupling theory based on GEOSLOPE and Morgenstern-Price slice method which considers the effect on suction, obtained by the computation:①four rainfall intensities, three rainfall duration,three water level rises rates, three water level falls rates, three types of landslides change pattern of groundwater seepage of slide body.②Landslides at processes of rainfall-infiltration, different rainfall intensities, different rainfall duration, the landslides' change regularity of stability coefficient.③Computational water level increase at the rate of 1 m/d, 3 m/d and 4 m/d, after the water level is stable at 175 m, decreasing at the rate of 0.67 m/d, 2 m/d and 3 m/d, after the water level is stable at 145 m, and the change regularity of stability coefficient of the three types landslides between water level of reservoir fluctuate and rainfall.4) Offer the calculation method for the landslides in Three Gorges reservoir, concreteprocess as follows:①identify landslides' type through trial computations.②For a landslide, identify it type based on monitor data and shapes of landslide.③Fix the most unfavorable working condition by the types of landslides and compute.④Choosing the appropriate rainfall intensities and rainfall duration, then obtain the revival criterion by calculation. By using the revival criterion calculation method, obtain the revival criterion of tanjiahe landslide, YanGuoshaba landslide and GanJuyuan landslide.The mainly new points and contributions of this thesis:1)Establish the categories of landslides which are suitable to research landslides' revival criterion and based on landslides' inducing factors.2)Detailedly analyzed the change regularity of stability coefficient of landslides in The Three Gorges reservoir under the circumstances which are different rainfall conditions, different water level of reservoir fluctuate conditions and rainfall conditions combine water level of reservoir fluctuate conditions.3)This thesis proposes the revival predication of landslide and the method of revival criterion which is suitable for the 585 landslides which are grave and revival landslides in Three Gorges Reservoir.