高应力厚层松软顶板煤巷围岩锚固失效及控制机理研究

With the increase of mining depth, the large area of anchor failure phenomenon often appears in thick soft-weak immediate roof of coal roadway under the effect of dynamic pressure which causes intense deformation of roadway and even local rock burst phenomenon. It brings a serious security risk. Taking the thick soft-weak roof of high-stress coal roadway as background, though theoretical analysis, similar material simulation experiment, mechanics experiment and combining with field test monitoring, the stress field distribution and the formation of load-bearing structures in thick soft-weak immediate roof of high-stress coal roadway are studied and the roof anchor cable failure mode and mechanism are analyzed. The impact of the anchor group preload to anchorage body characteristics and the anchorage body characteristics of broken coal and rock are studied. The Pre-tightening force to prevent the area development of plastic zone and crushing zone and the mechanism of two sides roadway supporting strengthen to prevent roof anchorage failure are analyzed. The principle of anchor cable support in the thick immediate roof of roadway is studied. Through the project, anchorage failure mechanism is revealed in thick soft-weak roof of high-stress coal roadway, of which supporting principle and technology on such roadway is put forward.

随着开采深度的增加，厚层松软直接顶煤层巷道在动压作用下常出现严重的围岩锚固失效，致使巷道剧烈变形甚至发生局部冲击矿压现象，带来严重的安全隐患。本项目以此类巷道为工程背景，通过理论分析、相似材料模拟实验、力学实验等手段，结合现场试验监测，研究高应力作用下厚层松软直接顶煤层巷道围岩应力场分布及承载结构的形成，分析其顶板锚索失效模式与机理；研究锚杆群预紧力对锚固体强度的影响，研究破碎煤岩锚固体力学特性；分析预紧力对阻止围岩塑性区、破碎区发育的作用机理，研究提高两帮支护强度对阻止顶板锚固失效的作用原理，研究厚层直接顶条件下锚索支护新技术。本项目的研究将揭示高应力作用下厚层松软顶板煤巷锚固失效机理，并提出锚固失效的控制原理与技术。

本项目以高应力厚层松软直接顶煤层巷道为工程背景，通过理论分析、实验室试验、数值模拟计算、现场工程应用等手段，研究了厚层松软直接顶板条件下，顶板锚索失效模式与机理；研究了锚杆预紧力对锚固体力学特性的影响分析；研究了预紧力对阻止围岩塑性区、破碎区发育的作用机理；研究了提高两帮强度对阻止顶板锚固失效的作用机理；研究了厚层直接顶条件下锚索支护原理，最后提出了一系列这类巷道的围岩控制技术，取得了以下创新性成果或发现：锚杆支护对围岩的蠕变控制机理概括为两个方面，一是分担围岩承受的载荷，二是等效增大围岩刚度，增强了围岩抵抗变形能力；充分发挥锚杆支护性能、延长锚杆支护时效、维持巷道处于稳定工作状态所需的空间需要同时满足两个条件，一是锚杆受载不超过杆体破断载荷，二是锚固基础位于塑性区之外；端锚锚固基础位于弹性岩体中能够最大程度发挥支护系统的承载能力；高应力软弱厚层直接顶板锚索孔施工过程中的变形和安装过程对锚固剂的破坏是导致锚索支护失效的主要原因；锚杆预应力及支护阻力无法控制深部巷道塑性区的发展，预紧力对抑制破碎区围岩的离层、剪胀等非连续变形作用较大，锚杆施加高预紧力可在围岩中产生较大压应力带，充分发挥锚杆主动支护作用与群锚功能，可有效降低塑性区向深处扩展速率；基于以上研究成果，提出了锚固设计新理念以及新方法，按照新方法设计的锚固支护方案大幅度提高了锚固力，显著改善了巷道的维护效果，取得了明显的社会经济效益，推动了巷道支护理论与技术的发展。