Research on large deformation mechanism and repair support technology of high stress soft rock roadway
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摘要: 针对高应力软岩巷道围岩破坏及持续变形,已发生大变形巷道如何科学合理返修支护等问题,以白皎煤矿+300水平4号石门运输大巷为例,根据巷道围岩钻孔窥视、围岩力学状况及支护技术综合分析了巷道围岩变形破坏特征,指出构造应力突出、巷道围岩岩性软弱、巷道集中布置、巷道围岩支护强度低、支护材料不匹配、施工质量不达标等是导致巷道持续变形的原因。指出对于已发生离层、破坏的巷道破碎围岩,仅采用锚杆、锚索补强支护时,围岩中不连续变形的存在会导致巷道围岩结构整体稳定性不足,无法有效抵抗应力的持续挤压作用,巷道易发生持续变形,需进行注浆加固将围岩中不连续变形产生的裂隙进行充填,进而通过锚杆、锚索进行支护。在此基础上,提出了“高压注浆+高强高预应力锚杆、锚索联合支护+喷浆”的巷道返修支护方案,即首先通过注浆加固将围岩裂隙及不连续结构面进行及时加固,进而通过强力锚杆、锚索支护对围岩进行支护,在围岩中形成承载结构,通过表面喷浆封闭围岩,阻止围岩风化,提高表面围岩稳定性。数值模拟和现场试验结果表明,采用“高压注浆+高强高预应力锚杆、锚索联合支护+喷浆”后,顶底板最大移近量为109 mm,两帮最大移近量为212 mm,能有效控制巷道围岩变形。Abstract: In the context of the destruction and continuous deformation of the surrounding rock of the high stress soft rock roadway, how to scientifically and reasonably repair and support the roadway that has undergone large deformation, and how to achieve effective control of the surrounding rock of the roadway. In order to solve the above problems, taking the No.4 crosscut transport roadway of Baijiao Coal Mine +300 level as an example, this paper comprehensively analyzes the deformation and destruction characteristics of the roadway surrounding rock based on the roadway surrounding rock observation boreholes, the surrounding rock mechanical condition and the support technology. It is pointed out that the prominent tectonic stress, weak lithology of the roadway surrounding rock, concentrated layout of the roadway, low strength of the roadway surrounding rock support, mismatch of support materials and substandard construction quality are the causes of the continuous deformation of the roadway. It is pointed out that for the broken surrounding rock of the roadway that has been separated and destructed, when only anchor bolts and cables are used to reinforce the support, the existence of discontinuous deformation in the surrounding rock will lead to insufficient overall stability of the surrounding rock structure of the roadway. Unable to effectively resist the continuous extrusion of stress, the roadway is prone to continuous deformation. Therefore, grouting reinforcement is required to fill the cracks caused by discontinuous deformation in the surrounding rock, and then anchor bolts and cables are used to further support the roadway. On this basis, a roadway repair support program of 'high-pressure grouting + high-strength and high-prestressed bolt and cable combined support + shotcreting' is proposed. Firstly, the surrounding rock cracks and discontinuous structural surface are reinforced in time by grouting reinforcement. Then the surrounding rock are supported by prestressed strong anchor bolts and cables support to form a bearing structure in the surrounding rock. The surface of the surrounding rock is sealed by surface shotcreting to stop the weathering of the surrounding rock and improve the stability of the surface surrounding rock. Numerical simulation and field test results show that after adopting 'high-pressure grouting + high-strength and high-prestressed bolt and cable combined support + shotcreting', the maximum displacement of the top and bottom plates is 109 mm, and the maximum displacement of the two sides is 212 mm. This method can effectively control the deformation of the roadway surrounding rock.
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