Study on Mechanical Properties and Damage Constitutive Model of Rock Mass with Different Fracture Lengths

This article, on the basis of experimental research, combines theoretical analysis and numerical calculation. In addition, the research, while taking into consideration different fracture lengths, confining pressure of rock mass mechanics properties, and behavior of evolution law, establishes and reflects the unique characteristics of the processes of fractured rock mass deformation and destruction of the damage constitutive model. In this instance, the discrete element method numerical has been discussed from the perspective of mesoscopic fracture mechanism of the fractured rock mass. The results show that the capacity of resistance of rock mass deformation and destruction along with the increase of fracture length, the peak stress of rock mass, the elastic modulus, and peak strain are positively correlated with the confining pressure. Furthermore, an increase in the confining pressure, transition of rock mass from brittle to ductile, an intact sample to shear failure pattern by stretching evolution, and different fracture lengths are characterized by shear failure form. Based on the statistical damage theory and Drucker Prager yield criterion, the damage constitutive model of fractured rock mass has been determined, and the physical meaning of the model parameters has been clarified through experimental analysis. The strength characteristics and damage evolution law of fractured rock mass revealed by the damage constitutive model are consistent with the test results, thereby verifying the rationality of the model. According to the numerical simulation of the evolution characteristics of the number of microcracks, the failure process of rock mass can be divided into four stages, namely crack initiation stage, crack steady growth stage, pre-peak crack accelerated growth stage, and post-peak crack accelerated growth stage. The simulation results of the deformation failure process and model are basically the same as those of the laboratory experiment. The theoretical results are expected to provide an important theoretical foundation for theoretical research of rock mass mechanics and engineering stability evaluation.