Whole process simulation method of brittle rocks deformation and failure considering initial voids closure and its influence

The constitutive model of rock materials is the basis of rock engineering design and analysis. The limi-tations that the present statistical damage constitutive model could not well reflect the mechanical properties of pre-peak de- formation of brittle rocks are considered to establish a simulation method that could accurately reflect the whole process of brittle rocks deformation and failure. Firstly,the initial voids closure and its influence are studied based on the anal- ysis of deformation mechanical characteristics of brittle rocks. Therefore,it can be divided into two types:the first type of initial voids and the second type of initial voids. The former could only be closed under hydrostatic pressure. The de- gree of closure affects the change characteristics of elastic modulus of brittle rocks and the unclosed part causes the in- itial damage of brittle rocks. The latter could be closed under arbitrary stress state and it could be completely closed at the initial macroscopic deformation stage. Both the initial compaction deformation stage and the initial macroscopic nonlinear deformation curvature are affected by the degree of closure. Secondly,brittle rocks are abstracted into two parts:fracture material and skeleton material. The method of brittle rocks deformation analysis is established based on the method of material deformation mechanics. The deformation analysis methods of fracture material and skeleton ma- terial are established respectively based on instantaneous strain and statistical damage theory and then the constitutive model of brittle rocks is established considering initial voids closure and its influence,and the methods of determining model parameters are given. Finally,the theoretical curves of the proposed model in this paper and other similar models are compared with experimental curves,and the effects of initial voids closure on the evolution of damage and addition- al damage of brittle rocks are discussed. The results show the theoretical model could accurately reflect the whole process of deformation and failure of brittle rocks,and could explain the relationship among confining pressure,initial voids and pre-peak deformation mechanical characteristics of brittle rocks. The rationality and feasibility of the model and method are verified.