Study On The Wetting Deformation And The Numerical Simulation Method Of HCRFD

Deformation control is one of the core problems in the design and operation of high earth-rock dams.The uncoordinated deformation of earth-rock dam will cause the dam crack.As an important factor that endangers dam safety during the first impoundement,the wetting deformation of dam upstream shell caused by flooding causes the obvious settlement and horizontal displacement of the upstream dam body,which easily leads to the uncoordinated deformation of the dam crest and the upstream and downstream dam slopes,and then cracks.The phenomenon is especially common in HCRFD(High Core-wall Rock-Fill Dam),such as Xiaolangdi,Pubugou and other dams.Therefore,it is of great of important to study the characteristics of wetting deformation and to develop numerical simulation for deformation and crack analysis methods of earth-rock dams.First,based on previous research results on coarse granular soil wetting deformation,this dissertation deeply analyzes the relationship between the wetting strains and proposes a new coarse granular soil wetting strain model.Then,combining the rockfill materials wetting deformation mechanism and process,how to consider the wetting deformation in the finite element analysis of the earth-rock dam is studied,and the nonlinear method and the elasto-plastic method for the calculation of the wetting deformation of the earth-rock dam are proposed and applied to the calculation of the wetting deformation of the actual project.At the same time,the smeared cracking model is used to simulate the cracks in the crest of the dam during the impoundment.Finally,based on the use of mesh encryption and parallel computation technology,the filling and impoundment process simulation of high earth-rock dams with a magnitude of more than one million elements was realized,and the Pubugou HCRFD was simulated.The research work of this dissertation mainly includes the following aspects:(1)By analyzing the results of wetting test,it have been found that the relationship between axis strain and volumetric strain is linear during wetting,the relationship between wetting axis strain and the wetting stress level is hyperbolic,and the relationship among the ratio k between wetting volumetric strain and wetting axial strain,average principal stress p and generalized shear stress q meet warped surface.In this dissertation,a new wetting strain model is proposed after the test results data fitting which reveals the relationship between q/p and k.(2)Based on the nonlinear elastic theory,combing with the proposed wetting strain model and the linear relationship between axis strain and volumetric strain in the process of wetting,and considering the rockfill materials modulus softening during wetting,this paper deduces the calculated method of wetting secant modulus and poisson's ratio.Then,the nolinear elastic wetting model and simulation method is proposed and applied to simulate the wetting deformation of the typical section of Guanyinyan rockfill dam.(3)Based on the elastoplastic theory,this paper modified the wetting plastic potential function of the two yield loci model in combination with the triaxial wetting test,and proposed wetting deformation elastoplastic simulation method by changing the mechanical parameters of materials.Then,developed the elastoplastic method FEM calculation program to simulate earth-rock dam,and simulated the filling and impoundment process of typical section of Guanyinyan rockfill dam.(4)The crack at the dam crest is predicted and analyzed using stress analysis method and deformation inclination method.At the same time,the smeared cracking model is introduced,the program to simulate the crack propagation using the smeared cracking model is developed,and the crack propagation during impoundment process of Guanyinyan dam is simulated.(5)A detailed FEM simulation method of earth-rockfill dams filling and impoundment is developed and applied to the Pubugou HCRFD numerical simulation.By using programming language,the modules corresponding to mesh generation,matrix storage and calculation and equation solution in numerical simulation of earth-rock dam are developed.