To investigate the influence of the geometry of a fracture and grouting on failure behaviors and mechanical properties of rock masses, uniaxial compressive tests were conducted on rock-like specimens containing single unfilled and grout-infilled flaws having different geometries. The compressive strength, deformation behaviors, and failure modes were studied and compared among the said specimens. Grouting improves the strength of grouted specimens through the following two mechanisms: (1) by increasing the shear-strength parameter values of the interface between the grout and model material and (2) by reducing the stress concentration at the flaw tips. Seven and eight crack types identified based on the crack geometry and crack-propagation mechanisms were used to analyze the failure modes of the specimens with the unfilled flaws and the grout-infilled flaws, respectively. An equivalent strength theory is introduced to predict the strength and the range of the flaw inclination angle of the grouted specimens for which the damage occurs along the interface between the grout and model material.

Soil‐rock mixture (SRM) is a special geological material that has the unique properties of rock or soil. Studies on the strength characteristics of the SRM have very important theoretical significance and practical value. In this study, the gravel proportions, gravel sizes, gravel shapes, and repetitive results of shear experiments are considered in laboratory experiments and for the identification of strength parameters. To the gravel shapes, from the angle of the composition materials of SRM, the experimental samples include samples with breccia gravels and with subrounded gravels. And, in this study, the laboratory model experiment is used to research the strength characteristics of SRM. In addition, the shear failure mechanism is used to establish the relationship between the microfailure mechanism and the macrostrength parameters identification. Taking gravel proportion, gravel size, gravel shape, and repetitive shear process as the influencing factors of the SRM, the laboratory models have been remolded, and laboratory direct shear experiments have been carried out. The shear deformation laws of the SRM are researched on the basis of the analysis of the curves of shear stress and the horizontal displacement.

Flaws existing in rock mass are one of the main factors resulting in the instability of rock mass. Epoxy resin is often used to reinforce fractured rock mass. However, few researches focused on mechanical properties of the specimens with a resin‐infilled flaw under triaxial compression. Therefore, in this research, epoxy resin was selected as the grouting material, and triaxial compression tests were conducted on the rock‐like specimens with a grout‐infilled flaw having different geometries. This study draws some new conclusions. The high confining pressure suppresses the generation of tensile cracks, and the failure mode changes from tensile‐shear failure to shear failure as the confining pressure increases. Grouting with epoxy resin leads to the improvement of peak strengths of the specimens under triaxial compression. The reinforcement effect of epoxy resin is better for the specimens having a large flaw length and those under a relatively low confining pressure. Grouting with epoxy resin reduces the internal friction angle of the samples but improves their cohesion. This research may provide some useful insights for understanding the mechanical behaviors of grouted rock masses.

Rock masses with open-closed cross-flaws are common in nature. The open-closed cross-flaws usually control the strength of rock masses. However, studies about the influence of open-closed cross-flaws on cracking behaviors and mechanical properties of rock masses are rare. In this study, rock-like samples containing open-closed cross-flaws with different geometries were fabricated to be conducted uniaxial compressive tests. The cracks observed in the tests were classified to nine types, and two new crack modes were described and identified. Two failure modes, failure caused by tensile cracks and failure caused by the combined effect of tensile and shear cracks, were observed. The failure caused by the penetration of the rock bridge is not observed, indicating that the rock bridge is not a potential penetration path for the samples with cross-flaws. Experimental results show that, when $α=0°$⁠, the peak stress decreases from 32.2 MPa to 17.0 MPa as $β$ increases from 0° to 90°. When $α=90°$⁠, the peak stress increases from 22.5 MPa to 40.0 MPa as $β$ increases from 0° to 90°. The inclination angle of the open flaw has an obvious effect on the strength of samples. When the inclination angle of the open flaw is 0°, the peak stress is the lowest (17.0 MPa). When the inclination angle of the open flaw is 90°, the peak stress is the largest (40.0 MPa). The samples with an open flaw of large inclination angle tend to have great compressive strength. For samples with open-closed cross-flaws, the open flaw has a greater influence on the strength and failure mode than the closed flaw.