The Damage Model Of Jointed Rock Mass Equivalent Behavior And Numerical Simulation

In the jointed rock mass, there are a great deal of joints which appear in small scale groups whose size differs from some centimeters to several meters. Their existence greatly changes the mechanical properties of the rock mass, which leads to the reduction of the distortion modulus and the strength parameter of the rock and behaves anisotropy. It is unrealistic to simulate so much joints one by one by using the traditional joint element model. In this paper, CDM (Continuum Damage Mechanics) is introduced to study and establish the constitutive model of the jointed rock mass. In the damage mechanics, the joints in the rock are seemed as a kind of damage and by introducing the damage variable to study the influence of joints to the rock, the constitutive model and damage evolution equation of the jointed rock are established on the basis of continuum mechanics theory. The advantage of this method lies in the following aspects, firstly, it doesn't take the mechanical behavior of individual joints into account rather than the macro mechanical effect of the joints. Secondly, in virtue of the damage variable which characterized in tensor, the constitutive relationship of the jointed rock which includes multi-group joints can be established easily.This paper introduces some basic conception and theory of the damage mechanics, and then discusses the method to obtain the damage tensor based on the investigation of engineering geology. By introducing the model of damage tensor, the mechanical properties of the joints in the rock mass can be reflected by the damage tensor and the net stress. Therefore, the problem relates to the jointed rock can be easily solved within the scope of macro continuum damage mechanics.The paper focuses on the following work: (1) established the jointed rock damage tensor and the damage analysis model; (2) successfully compiled the 2-D damage finite element program. (3) the comparison between the damage model and the jointed element model is performed as well as the analyses of different joint angle, different joint spacing, different joint length etc with the damage model; (4) the preprocessor and postprocessor such as ANSYS and TECPLOT are used to construct the model and view the results visualized.The results of the comparison between the damage model and the jointed element model indicate that the damage model is applicable. Moreover, damage model can reflect the anisotropy and discontinuity of jointed rock more efficiently than jointed element model. It can be used to study the mechanical properties of rock mass with small scale and large amounts of joints.