A uniaxial compression damage model for rockmass considering the crack deformation parameter

In order to accurately predict the effect of crack on the rockmass compression mechanical property such as strength and stiffness, a more reasonable compression damage model for the cracked rockmass is needed to be established. On basis of the relevant experimental data and mechanical behavior of the cracked rockmass under uniaxial compression, some deficiencies in the existing compression damage models for the rockmass with intermittent cracks are analyzed in detail. Three improvements are made to improve the existing methods, e.g., the crack deformation parameter is not taken as a constant, the negative first stress intensity factor K_I produced by the normal stress on the crack face is considered, and K_I produced by the effective shear stress on the crack face is considered. A revised uniaxial compression damage model for rockmass considering the crack deformation parameter is proposed and the validity of the proposed model is verified with the experimental data. The results show that the prediction of the rockmass elastic modulus and damage under uniaxial compression with the proposed model are more accurate than those obtained with the existing models. Especially, when the crack dip angel is 0°, the rockmass elastic modulus obtained with the proposed model is 4.306 MPa, which is nearly equal to its tested value 4.310 MPa. The proposed model can perfectly describe the rockmass mechanical behavior under uniaxial compression, which also indicates that it is very necessary to consider the effect of the crack deformation parameter on the rockmass uniaxial compression mechanical property. This study can provide references for accurately predicting the rockmass mechanical behavior under uniaxial compression.