Shear Rheological Characteristics and Nonlinear Constitutive Model of Serrate Structure Surface

In order to investigate the creep and stress relaxation characteristics of rock mass discontinuity with different slope ratios, the creep and stress relaxation tests of dentate discontinuity poured by cement mortar on the condition of shear stress are carried out by using a biaxial creep machine. First, the comparison of creep and relaxation was made. Secondly, the establishment and solution of nonlinear rheological constitutive model were discussed. Final, nonlinear rheological equation was used to fit the test curve. According to the test results, both creep curves and relaxation curves can be divided into three stages: the instantaneous stage, attenuation stage, and stable stage. From the energy perspective, creep is the process of energy accumulation and dissipation, and stress relaxation is the process of energy dissipation. The constitutive equation of nonlinear rheological model should be deduced by using rheological theory. The initial condition of creep is different to that of relaxation when the finite integration method and Laplace transformation is used to solve equations. The creep equation and relaxation equation of the nonlinear-parameters Maxwell model are obtained by determining the relation between the viscosity coefficient and time, and the equation curves agree with the test results. The parameter values of the creep equation is different to that of relaxation equation, which reveal that the creep properties are not equivalent to the relaxation properties and creep and relaxation cannot be mutual conversion.