Study On Evolution Law And Mechanism Of Slow Deformation Wave In Rock Mass

Under the action of internal and external factors of the earth,a slow deformation wave will be produced in the crust,which plays an important role in the formation and occurrence of earthquakes.In the thesis,the formation and propagation characteristics of slow deformation waves in the crust are discussed by means of experimental research and theoretical analysis.A nonlinear continuous phase transition model describing the propagation characteristics of slow deformation wave is established,and the semi analytical and numerical solutions of the corresponding characteristic governing equations are solved,which are compared with the experimental results.Based on this model,the evolution law of plastic zone of deep surrounding rock is predicted.The main research results are as follows:1.Through the method of speckle photography,the micro characterization and observation of the rock mass surface in the deformation process of red sandstone sample under uniaxial compression are carried out.Through the treatment of DIC technology,the deformation transfer process with clear space-time frequency is presented in the loaded deformation sample,and the deformation transfer characteristics of the sample in the loading process are obtained.2.Using gauge theory and phase transformation theory,the elastic-plastic model of geotechnical materials with dissipation is established by selecting displacement and plastic distortion tensor as independent variables.Plastic distortion tensor contains all the information of plastic deformation of rock materials,and it is appropriate to take it as the main unknown.The physical meaning of gauge invariance is to realize compatible plastic deformation.The initial Lagrange function is constructed according to the invariance of Lagrange function to translation transformation.The development of irreversible deformation is accompanied by the continuous internal structure transformation of rock.In order to consider the continuous phase transition of this type of results,according to Ginzburg Landau’s potential energy expansion theory,the quartic and hexagonal terms of distortion tensor are added to the initial Lagrange function.The differential equations of motion considering dissipation and boundary conditions are obtained by using Hamilton principle.Based on the variational principle of kinematics,the generalized Hooke’s law is obtained.3.Starting from the phase transition theory of slow deformation wave,the phase transition theory is used to establish the model of slow deformation wave in two dimensions.The theoretical model is used to preliminarily analyze the slow deformation wave,control the relevant variables,temporarily ignore the viscosity term and inertia term,calculate the phase transition theoretical formula,and calculate the relevant results in the form of semi analytical solution,i.e.approximate analytical solution,Because it involves nonlinear problems,two forms of analytical solutions are adopted.The second analytical solution method well simulates the nonlinear phenomenon.The trend of the experimental data is consistent with the theoretical curve.The theoretical curve better simulates the experimental curve,which has great similarity and certain numerical comparability,It can reflect the numerical change of vertical strain before rock failure,and the amplitude and frequency are consistent.4.The form and characteristics of the solution are analyzed by using the phase plane analysis method,and the kink wave solution,solitary wave evolution solution and traveling wave evolution solution of the nonlinear equation are obtained.The form of the above solution can comprehensively and clearly describe the evolution process of the order parameter(deformation)with time.5.The deformation and failure of deep surrounding rock can be regarded as the transformation of its mechanical properties from solid to fluid.The transformation process is a continuous process with the characteristics of continuous and gradual phase transformation.The evolution law of deep surrounding rock is analyzed from the perspective of energy and deformation.