关键词: 管索组合结构, 锚索, 双剪试验, 剪切破断, 剪切强度

Abstract: In order to prevent the anchor cable from shearing and breaking in the surrounding rock of the roadway, and to further improve the shear strength of the anchor cable, we independently developed the anchor cables combined with the c-shaped tube (ACC), which can improve the shear strength and stability of the surrounding rock. The design is mainly composed of c-shaped tube and anchor cables. We first introduce the ACC support structure in detail. In order to better study the mechanical properties of ACC, the indoor mechanical properties tests of ACC and pure anchor cables have been carried out with different types, different prestresses and different cable diameters, with the help of the self-developed new type of anchor able with c-shaped tube tension-shear testing system. We compare and analyze the test results based on the characteristics of the force-shear displacement plot, the effects of the supporting member type, and the failure mode of the supporting structure. The results show that the anchor cable and its combined structure with c-shaped tube undergo three stages in the shearing process, which includes the free deformation of the bore-wall rock, the compression of the c-shaped steel tube by the bore-wall rock, and the joint deformation of the c-shaped tube wrapped with the anchor cable. The shear fracture of ACC is manifested as tensile fracture and tensile-shear composite fracture. Its peak shear force is negatively correlated with the pretension force. Compared with the pure anchor cable, the axial distance of the shear plastic hinge of ACC is larger. The maximum shear force, the maximum axial force and the overall structural deformation capacity of ACC have been improved by 26.8%, 3.5%, and 7%, respectively. The test results show that the use of ACC can effectively improve the overall shear resistance of the joint surface. When the surrounding rock is deformed and damaged, the combined structure of the anchor cable and the c-shaped steel cube can not only increase the shear strength of the entire supporting system, but also increase the tensile strength of the anchor cable at the same time. Therefore, the supporting effect of the anchor cable plus the c-shaped tube can achieve the fact where 1+1>2. The combination of two forms an effective surrounding rock bearing circle around the roadway, and the stability can be guaranteed for the surrounding rock of the roadway.

Key words: anchor cable with c-shaped tube (ACC), anchor cable, double shear test, shear failure, shear strength