管索组合结构及其力学性能研究

为防止在巷道围岩中锚索发生剪切破断，进一步提高锚索的抗剪强度，自主研发的管索组合结构能更好地提高围岩的抗剪强度及稳定性，该结构主要由C型钢管和锚索组成。在详细介绍了管索组合结构支护结构的基础上，为了更好地研究管索组合结构的力学性能，利用自主研发的新型管索拉剪试验系统分别对不同类型、不同预应力、不同索径的管索组合结构及纯锚索进行了室内力学特性试验，分别从受力?剪切位移曲线特征、支护构件类型影响和支护结构破断模式等方面对比分析了试验结果。结果表明，管索组合结构在剪切过程中经历孔壁岩石自由变形、孔壁岩石压缩C型管、C型管握裹锚索共同变形3个阶段；管索组合结构的剪切破断形式表现为拉伸破断和拉剪复合破断，其峰值剪力与预紧力呈负相关，且与纯锚索相比，管索组合结构的剪切塑性铰的轴向距离较大，管索组合结构的最大剪力、最大轴力以及整体结构变形能力均得到提高，提升率分别达到26.8%、3.5%和7.0%以上。试验结果表明，采用管索组合结构可以有效提高结构面的整体抗剪能力。当围岩发生变形破坏时，锚索与C型钢管的组合结构不仅可以增加整个支护系统的抗剪强度，而且可以同时提高锚索的抗拔能力，从而实现锚索+C型钢管1+1＞2的支护效果，在巷道周围组成有效的围岩承载圈，实现巷道围岩的稳定。

Research on the anchor cable combined with the c-shaped tube and the mechanical properties

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.