Effects Of Reservoir Water Level Fluctuation On Deformation And Stability Of The Rock Bank Slope

Water is the most important factor leading to the development and occurrence of landslide,and it is also the key factor which is the most difficult to determine and quantitative study.In depth study of the influence of reservoir water level fluctuation on the deformation and stability of bank slope rock mass,it has important practical significance to comprehensively understand the failure mechanism of this type of landslide and the prevention and treatment of landslide hazards.The paper pays attention to solving the urgent deformation and stability problems of bank slope rock mass of the reservoir engineering construction under reservoir water level fluctuation,based on the related subject of research on the deformation and stability of high steep rock slope in left bank of the Jinfoshan water conservancy project,it takes the project of high and steep reservoir slope the main background and research object,and it focus on deformation and stability of rock slope under reservoir water level fluctuation,using such methods as field investigation and observation,field test,theoretical analysis and numerical simulation research to conduct following main works:(1)Based on the Continnum equation and Darcy Law of mass conservation,the uniform basic equation of three-dimensional saturated-unsaturated seepage was discussed.Based on the virtual work principles,the saturated-unsaturated rock soil coupled consolidation equations was dissertated under the double field interactions effects coupling is considered,Based on the Boussinesq diferential equaion of unsteady-seepage,Laplace positive and inverse variations and appropriate improvement algorithm,The theoretical solution on fluctuation function of groundwater level was derived and analyzed in detail in the slope rock mass to guide the thinking for the numerical simulation test scheme design and comparative analysis for the test.(2)Based on the theory of Complex Functions,polar coordinate solution of elliptic hole,and Stevenson proposed hyperbolic form Goursat stress function,the stress and displacement of slope fissured rock mass were derived.and it was combined with the specific analysis of the actual situation for this paper to provide the theoretical support for numerical test results analysis.Based on the statistical analysis of the hydrogeological conditions and the physical and mechanical properties of rock mass,the physical and mechanical parameters of the rock mass wre determined,and the scientific and factual input data was provided for the numerical experiments.(3)The numerical simulation tests were carried out under various working conditions for the slow change of reservoir water.In order to study the influence on slope deformation and stability of slope fracture,permeability coefficient,elastic modulus and pore water for the whole process of reservoir water level fluctuation and permeability coefficient for single water level decline,It analyzed the effects of the influence factors on bank slope rock mass deformation displacement,“approximate creep deformation”,stress,seepage velocity,pore water pressure,phreatic line characteristic and stability coefficients according to the need of further research to reveal phreatic line distribution change law and seepage field dynamic change characteristics under various conditions of bank slope in the process of water level fluctuation.(4)The numerical simulation tests were carried out under various working conditions for the rapid change of reservoir water.In order to study the influence on slope deformation and stability of water level variation velocity,slope fracture,permeability coefficient for the whole process of reservoir water level fluctuation,and water level(extreme)falling velocity for single water level decline,It focus on the effects of water level variation velocity on bank slope rock mass deformation displacement,“approximate creep deformation”,stress and stability coefficients.(5)The unloading of rock mass will cause redistribution and adjustment on the fields of stress and strain in the rock mass near the surface,the “stress reduction” of the local rock mass caused by the whole process of slope excavation and reservoir water level fluctuation was considered as the “unloading” of the local rock mass,on the basis of rock unloading mechanical model and in consideration of rock unloading's impact on the dynamic process of rock mass parameter weakening,using FISH language to conduct secondary development of FALC3 D finite differential software,to build the approximate detailed three-dimensional numerical model for high bank slope.numerical simulation test was carried out under the whole process of slope excavation and the rapid change of reservoir water.The deformation displacement of rock slope and quantitative analysis of the unloading area under unloading effect were analyzed,and make a contrastive analysis on the deformation displacement between the numerical models with and without unloading.The results show that the number of the areas covered with different unloading rates increases gradually in the overall trend,in particular,the tensile stress region increases to about 97300 m3 and mainly occurs near the top of the Crack X2;without taking into account the unloading effect,the effect of deformation on the rock mass is delayed.(6)The above tests results show that the deformation displacement of the slope rock mass is relatively large and the stability is poor when unloading,which was applied to the Jinfoshan water conservancy project.the numerical simulation test was carried out under the whole process of slope excavation and the rapid change of reservoir water considering the dynamic comprehensive influence of the fluid solid coupling effect and unloading effect.It analyzed the change analysis of rock slope deformation displacement,stress,unloading area,rock modulus,pore-water pressure and axial force of the anchor under unloading effect,and makes a comparison between the numerical simulation results and the field monitoring data of excavation stage.The result shows that both data are coinsident well;the deformation of rock mass is small and the stability is good at each stage.The related theories and results provide guideline and foundation for the correlational research on post-stage construction and operation of the reservoir area;and it also can offers guidance and reference to the study of similar water conservancy projects.