Strong Finite Element Numerical Simulation Of Layered Rock Based On Cosserat Theory

As one of the most important engineering rock masses,the layered rock mass has a special structure and obvious anisotropy in mechanical properties,which has a greater impact on the overall stability of the rock.Due to the existence of the weak surface of bedding,the rock will be discontinuous under load.The discontinuous interface will cause stress concentration in the process of stress transfer,which will reduce the stability of the rock.As the mining of the mine gradually develops into the deep part,the deep layer The stability of rock-like rocks has become more and more prominent.At present,the Cosserat theory has been widely used in rock mechanics.The micro-rotation introduced in this theory can well describe the anisotropic characteristics of layered rocks.Combined with the finite element method,the macroscopic behavior of the rock under stress can be obtained through numerical simulation.Microscopic force and deformation characteristics.This thesis takes the layered rock as the research object,through a combination of theoretical analysis and numerical simulation,the deformation characteristics and stability of the layered rock under local load are studied.The elastic constitutive model established based on the general Cosserat medium theory is used to describe the bending characteristics of the layered rock,combined with the differential quadrature method(GDQ)and the mapping technology,the strong finite element formula of the Cosserat layered rock is derived,and it is carried out by Matlab independent programming.Numerical simulation of finite element(FEM)and strong finite element(SFEM)to analyze the stability of layered rocks.The main research conclusions of the thesis are as follows:(1)Based on the general Cosserat theory,the Cosserat elastic constitutive model of simple layered rock and interbedded rock is discussed.Aiming at the discontinuity of layered rock under stress concentration,combined with differential quadrature method and mapping technology,it is limited to the general The domain decomposition technique in the element method and the method of solving high-order differential equations are improved,and a strong finite element method is proposed.(2)The strong finite element formula of Cosserat layered rock is deduced,and the Cosserat static equilibrium equations and the overall stiffness matrix in the form of compact matrix in displacement mode are obtained.In view of the local load of the isotropic Cosserat elastomer and the transversely isotropic Cosserat layered rock,different mechanical parameters were adjusted,and FEM and SFEM were used to carry out numerical simulation experiments on them.According to the simulation results,the normal stiffness,The influence of three mechanical parameters,tangential stiffness and Cosserat second shear modulus,on the stability of layered rock.(3)Through numerical simulation experiment and result analysis,it is concluded that strong finite element(SFEM)is a more reliable,simpler,and more accurate numerical calculation method than finite element(FEM),which can well solve the discontinuity caused by stress concentration.problem.Numerical calculation results show that both the normal stiffness and tangential stiffness of the bedding will have a greater impact on the stability of the rock formation,and the existence of the weak surface of the bedding weakens the stress transfer effect.The value of the second Cosserat shear modulus has a certain influence on the simulation results.The rock exhibits a significant stress concentration effect under a large second shear modulus.