A novel approach for applying active surface pre-stress on surrounding rocks of roadways by backfilling behind surface support
YUAN Guiyang;GAO Fuqiang;WANG Tao;LI Jianzhong;WANG Xiaoqing
针对松软煤体巷道护表构件主动支护效应差、局部裸露围岩破碎范围持续扩大导致的锚杆、锚索失效问题,开发了网后注浆面型预应力施加技术并进行了实验室试验及现场验证。首先分析了锚网支护围岩变形破坏方式及控制方法,阐述了网后注浆技术原理;其次开展了不同规格型号金属网的网后注浆实验室试验,分别得到了主动面型预应力施加过程中锚杆受力、注浆压力、护表构件变形量及面应力演化规律;最后开展了现场工况下的顶板及两帮网后注浆试验,得到了护表构件在一定变形量前提下的面型预应力施加值,验证了网后注浆技术的适用性。研究结果表明:① 金属网与煤壁之间存在间隙是导致支护系统主动支护能力差和锚杆、锚索支护失效的主控因素,围绕金属网与煤壁接触面凹凸不平的结构间隙进行注浆填充、全面封闭围岩是完善锚网支护系统的技术手段;② 在金属网与围岩之间进行注浆充填可实现面型主动预应力的施加,面应力变化趋势主要分为:初始面应力恒定阶段、面应力上升阶段、面应力降低至稳定阶段;③ 网后注浆过程中,面应力变化趋势与注浆压力、金属网变形量紧密相关,面应力上升过程中,注浆压力、金属网变形量也随之升高;④ 网后注浆可缓解锚杆托盘应力集中程度,面应力上升过程中可使得应力集中的锚杆预紧力呈现出小幅度降低趋势,受力较为均匀的锚杆预紧力呈现出同步上升趋势。所得研究成果有望成为锚杆支护配套技术,为复杂困难巷道治理提供技术储备与理论参考。
In response to the poor active support effect of the surface protection components in soft coal roadway and the continuous expansion of the broken range of local exposed surrounding rock, which leads to the failure of anchor rod and cables, a mesh grouting surface type prestressed application technology has been developed. The authors conducted post mesh grouting tests on different specifications and models of metal mesh, and obtained the mechanical response characteristics of the support system during the application of active surface prestressing. Based on this, the post mesh grouting tests on the roof and two sides of the mesh under on-site conditions were carried out, verifying the applicability of post mesh grouting technology. The research results indicate that: ① There is a gap between the metal mesh and the coal wall, which leads to poor active support ability. The continuous expansion of the broken range of the exposed surrounding rock is the main controlling factor for the failure of anchor rod and anchor cable support. Filling the uneven structure around the contact surface between the metal mesh and the coal wall, increasing the active support ability of the protective surface components, and comprehensively sealing the surrounding rock are the technical means to improve the anchor mesh support system; ② Injecting and filling between the metal mesh and the surrounding rock can achieve the application of surface active pre-stress. The trend of surface stress change is mainly divided into: the initial stage of constant surface stress, the stage of increasing surface stress, and the stage of reducing surface stress to stable state; ③ During the process of grouting behind the mesh, the trend of changes in surface stress values is closely related to the grouting pressure and deformation of the metal mesh. During the process of increasing surface stress, the grouting pressure and deformation of the metal mesh also increase accordingly; ④ Grouting behind the mesh can effectively alleviate the stress concentration of the cable tray. During the process of increasing the surface stress value, the pre-tightening force of the cable with stress concentration can show a small decrease trend, while the pre-tightening force of the cable with relatively uniform stress shows a synchronous upward trend during the process of increasing the surface stress value. The technologies developed are expected to become supporting technologies for rock bolt support, providing technical and theoretical references for the treatment of complex and difficult roadway.
rock bolting;metal mesh;backfilling behind mesh;surface active pre-stress;ground control
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会