| As a highly destructive geological disaster,landslides are characterized by high frequency,high lethality,wide range,easy to induce secondary disasters,and huge maintenance and repair costs,which pose a huge threat to human life and engineering safety.Groundwater is one of the most important factors that trigger landslides.Especially under the background of climate change and increasing engineering activities,the frequency and hazards of groundwater-induced landslides(like rainfall and reservoir water)are also increasingly prominent.Therefore,studying the stability of slopes,especially the mechanism of groundwater impact on slope stability,has important theoretical and practical significance for human life safety,engineering safety,environmental protection,and disaster prevention.Based on the combined finite-discrete element method(FDEM),this thesis focus on the simulation of the landslide evolution process,and the slope stability analysis under the water-rock coupling effect.The main work is as follows:(1)As the FDEM has shortcomings in systematically simulating the sliding process,several improvements were carried out on the original program,and the FDEM-slope program which can be used to consider the whole process of the landslide was also developed.Some verification examples are also given,which show that the FDEM-slope program can effectively and accurately simulate the entire process of slide evolution from continuous to discontinuous,from stable to unstable.(2)A numerical representation method for various types of structural planes in FDEM-slope was first established,and then numerical studies on several common rock joint landslides in engineering practice were conducted.The results show that the structural planes and rock bridges in the jointed rock slope are the most important factors controlling the deformation law,failure mode and evolution process of the landslide.The FDEM-slope method can well reflect the deformation and failure laws of different structural planes,and effectively reveal the failure mechanism and failure characteristics of jointed rock slope.(3)In order to accurately describe the seepage characteristics of groundwater in rock and soil,the theoretical framework of the continuous-discrete medium coupled seepage model for fracture-matrix dual medium was established.Then a saturated-unsaturated transient flow seepage algorithm for discrete-continuous dual-medium was also developed.The results the of verification example show that the seepage algorithm is feasible and correct in dealing with the seepage analysis of fractured rock masses,which provides the necessary calculation basis for studying the seepage field changes in the slope.(4)A slope stability analysis program under the water-rock coupling condition,named FDEM-slopew,is developed by combining the continuous-discrete medium coupled seepage model and the FDEM-slope solid program.The stability of the ideal slope under different rainfall conditions and the fluctuation of the reservoir water level is then simulated.Results show that the effect of rainfall has a weakening effect on the slope stability,and the degree of weakening is controlled by both the rainfall intensity and the permeability coefficient of the slope;During the fluctuation of the reservoir water level,the stability of the slope is directly related to the fluctuation of the reservoir water level: The safety factor increases when the reservoir water level rises and decreases when it falls.(5)Using the FDEM-slopew software,the stability variation of Majiagou landslide project in the Three Gorges reservoir area was simulated and analyzed under the combined action of rainfall and reservoir water.The study found that the fluctuation of reservoir water level is the main factor of stability change,and rainfall has a weakening effect on slope stability,and the impact is small. |
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