Study on statistical damage model of rock considering void effect

In order to obtain the deformation characteristics of rock under different confining pressures and the influence of rock voids on deformation damage, the indoor triaxial compression test was carried out on the sandstone using the TAW-2000 rock test system.A triaxial compression statistical damage model considering rock void damage was constructed, and a method for determining distribution parameters and void damage influence coefficients was proposed.By comparing the model curve and the test curve, the correctness and rationality of the established damage model were verified.The results show that the model can describe the damage evolution well by introducing the void damage influence coefficient to the traditional damage model.And it can reflect the softening characteristics of the triaxial compression test curve.This model introduces the void damage influence coefficient to the traditional failure model, which can describe the damage evolution well and reflect the softening characteristics of the triaxial compression test curve.The variation laws of damage variables of rocks under the same confining pressure all show a trend of increasing first and then tending to be stable.This is because the internal primary fractures of the rock will further develop and spread under the load.Until the penetration is a macroscopic fracture, the rock will be deformed and damaged.In the subsequent test, the rock sample slipped along the fracture surface, and finally the damage degree of the rock was gradually increased.It can be seen from the fitting results that the established statistical damage model can better reflect the deformation characteristics of the rock.It can also reflect the deformation of the surrounding rock of the roadway more realistically, which has guiding significance for the design of the surrounding rock-support body of the roadway in practical engineering.However, the magnitude of the three-dimensional stress on the surrounding rock varies in practical engineering.In view of the fact that the constraints of the test conditions cannot be realized, it is necessary to perform true triaxial tests on the rocks in the future research in order to better reflect the stress and deformation of the surrounding rock after the actual formation is excavated.