Numerical Analysis on the Joint Weakening Effect of Rock Mass Behaviors in Tension

Abstract

Abstract The presence of joints and other types of discontinuities has a significant effect on the mechanical properties of rock, especially for tensile properties to fundamentally influence the stability of rock excavations. The main challenge associated with the experimental research on jointed rock lies in the difficulty to carry out amount of direct tensile tests for analysis of the effect of joint geometric parameters on mechanical properties. In this study, a particle flow model was established by utilizing the flat-joint contact model (FJM) to represent the rock materials. After microscopic parameter calibration, 53 sets of the numerical model were used for investigating the relationship between jointed geometric parameters and tensile mechanical properties. The results show that the crack initiation is related to trace length l and joint angle β, and the tensile-shear crack will appear as β increase. The uniaxial tension strength σt and β had first a weak negative correlation and then a positive correlation as the β increases, which was consistent with mathematical calculations. Furthermore, the relative importance (RI) analysis showed that the β plays a decisive role among the joint geometric parameters for affecting σt, and the effect factors of σt were joint angle β, length l, density n, and aperture d in that order. The present research can be utilized for multiple purposes in the field of jointed rock engineering, such as prediction of surrounding rock instability analysis and estimating the variable values in the inversion analysis in practical engineering projects.