Study On The Dynamic Damage Constitutive Model Of Jointed Rock Mass By Comprehensively Considering Macro And Meso Defects

In practical engineering, there is a rock joint, bedding, micro cracks and holes and other defects, according to the geometrical dimensions, they can be divided into macro and meso defects. But the current research on the dynamic mechanical properties of rock mass ignored the characteristics, and so we should establish the dynamic damage constitutive model of jointed rock mass by comprehensively considering macro and meso defects. In this paper, the main research contents are as follows:(1) This paper makes the rock dynamic compression test by use of SHPB devices, studies the failure mode and mechanism of the rock mass, and analyzes the influence of the joint angle, penetration degree and sample aspect ratio on the dynamic mechanical properties of rock mass, and draws some conclusions.(2) This paper studies and analyzes the failure mode of rock mass from macroscopic and microscopic view, summarizes the law of the procession about cracks initiation, propagation and coalescence. On the basis of this understanding, the failure mechanism of rock mass is analyzed, the crack initiation criterion is proposed,and the direction and the length of wing crack propagation are calculated and analyzed by using the theory of rock fracture mechanics.(3) We further study on rock mechanics mechanism, based on the rock dynamic damage on the classical TCK model. In consideration of the mechanical properties of rock and the crack tip stress field, We define and calculate the macroscopic damage variable of rock mass, get the coupling damage tensor of rock mass by calculating the coupling of rock mass macro and meso damage variable on basis of the Lemaitre strain equivalent hypothesis. so we finally establish a constitutive model of rock mass.(4) Assuming that the rock mass is regarded as an equivalent continuum model is composed of rock material and structural elements, So we establish the damage constitutive model of rock based on dynamic deformation element, And verify the model by examples, and discuss the influences of loading strain rate and joint angleon the dynamic mechanical properties of rock mass. Finally reach some conclusions.