Dynamic constitutive model of penetrating jointed rock mass based on ZTW model

Abstract

According to the characteristics of stress-strain curves of soft rock with through joints under dynamic loading and the related research results of existing dynamic constitutive models of soft rock, a dynamic uniaxial compression constitutive model for soft rock with through joints is established. The model is based on Zhu-Wang-Tang model, in which damage body, joint plane closure element and shear deformation element are connected in series to simulate the static compressive mechanical properties of jointed rock mass, and Maxwell composite element is connected in series to describe the strain rate effect of jointed rock mass. First, the micro-damage model is described assuming that the integrity of the intact rock mass follows the tensile strain criterion and the statistical damage of the micro-intensity and damage satisfying the Weibull distribution; Secondly, the Mohr-Coulomb strength criterion is introduced into the strength damage variable to modify the macroscopic damage variable according to the shear failure characteristics of the through-jointed rock mass along the Plane-straight joint plane under uniaxial compressive load. Thirdly, based on the Lemaitre equivalent strain hypothesis, a coupled damage variable (tensor) considering the macroscopic and microscopic effects is established, and then the damage viscoelastic dynamic constitutive model of the jointed soft rock is established. Finally, the model is used to discuss the effects of joint cohesion, joint internal friction angle and joint dip angle on the dynamic mechanical properties of rock mass. The results show that the uniaxial compression dynamic peak strength of jointed rock mass increases with the joint cohesion and the internal friction angle of the joint, and U-shaped with the increase of the joint inclination angle, and the minimum value is obtained at 60°.