Anisotropic shear behavior of closely jointed rock masses

In-situ shear tests on a closely jointed rock mass containing two sets of joints, one continuous and another staggered, were conducted. A series of laboratory shear tests with varying combinations of loading conditions and geometrical characteristics of rock joints were also carried out. A Discrete Element Method (DEM) was used to numerically simulate the in-situ and laboratory shear tests. The in-situ tests, laboratory tests and numerical modeling were aimed at evaluating the anisotropic shear behavior of closely jointed rock masses. Comparison between the test and simulation results of this study with the results of similar laboratory tests was completed. The simulation results agreed well with the laboratory test results and provided slightly higher shear stresses comparing to the results of in-situ shear tests. The test and simulation results showed that the jointed rock masses exhibited a strong anisotropic shear behavior, the significance of which depended on the orientation of the continuous joint set. Different failure mechanisms were confirmed in the tested and simulated rock mass models with different geometrical characteristics of rock joints, which resulted in the anisotropic shear behavior.