Loading directionality of single-through fissure effects on mechanical properties of grouted rock

Grouting reinforcement of rock masses containing numerous joints and fissures is significant for ensuring the safety of deep mining and underground structures. To quantify the influence of fissure loading directionality on the mechanical properties of grouted rocks, Brazilian splitting tests of grouted rocks were conducted with acoustic emission and digital image correlation monitoring. A corresponding three-dimensional discrete element model was constructed to reproduce the crack and force chain evolution laws during the loading process of grouted rocks in Brazilian splitting tests. The failure mechanism of grouted rocks under different angles between loading direction and through fissure was analyzed. The results show that the mechanical properties of grouted rock initially increase and then decrease as the loading angle increases, and the failure transitions from being dominated by interface fracture to medium splitting. The strain-concentrated zones of all grouted rocks are located along the loading direction in the middle part of the specimen. As the angle increases, the strain-concentrated zone shows a significant inclination. When the angle is small, cracks tend to extend and propagate more readily at the interface. As the angle increases, the number of cracks induced by the tensile-shear failure of the grouted rock interface gradually decreases. The main load-bearing force chains also show an offset, which is highly consistent with the crack evolution. The distribution of high-strength force chains is distinctly directional, with the main tendency aligning with the strain field. The specimen exhibits higher mechanical properties when the high-strength force chains are more uniform and larger.