采动下淋水软岩巷道围岩变形破坏特征

Study on deformation and failure characteristics and support optimization of surrounding rock in strong water-drenching soft rock roadway

  • 摘要: 软岩巷道在采动影响以及淋水浸蚀双重作用下,巷道围岩变形破坏严重,且淋水使锚固剂失效,造成锚杆及锚索锚固力衰减,承载能力下降,严重影响工作面安全生产。以某煤矿为工程背景,采用物理相似模拟实验、数值模拟实验与现场实测相结合的研究方法,分析了淋水软岩巷道围岩在采动影响及不同支护参数条件下的破坏情况,揭示了在采动下淋水软岩巷道围岩变形破坏特征并给出了合理的支护参数。结果表明:软岩巷道受采动影响围岩变形破坏形态表现有非对称性,且在淋水条件下,巷道围岩破坏范围进一步增大。随着锚索长度从9m增加至10m,巷道围岩破坏范围减小了4.3%;使用12.2m长锚索顶板、两帮破坏范围大于使用9m锚索与10m锚索,其主要原因为12.2m锚索贯通至顶板含水层,导致水体渗流加剧,巷道围岩进一步软化;使用“9.2m长锚索+4.2m短锚索”联合支护时,巷道围岩破坏与水体渗流情况相较之前支护参数均有显著减小,相较前三种支护方案中破坏范围最小的10m锚索减小了37.5%。根据物理相似模拟与数值模拟实验结果,提出了“9.2m长锚索+4.2m短锚索”联合支护的支护方式,现场应用显示巷道顶板下沉量明显减少,有效控制了巷道围岩变形破坏。

     

    Abstract: Under the dual effects of mining influence and water erosion in soft rock roadway, the deformation and failure of surrounding rock of roadway are serious, and the water spray makes the anchoring agent fail, resulting in the attenuation of anchoring force of bolt and anchor cable and the decrease of bearing capacity, which seriously affects the safety production of working face. Taking a coal mine as the engineering background, the research methods of physical similarity simulation, numerical simulation and field measurement are used to analyze the failure range and fracture development of water-drenched soft rock roadway under the influence of mining and different support parameters. The deformation and failure characteristics of surrounding rock of water-drenched soft rock roadway under mining are revealed and reasonable support parameters are given. The results show that the deformation and failure modes of surrounding rock in soft rock roadway affected by mining are asymmetric, and the failure range of surrounding rock in roadway increases further under the condition of water spraying. As the length of the anchor cable increases from 9m to 10m, the damage range of the surrounding rock of the roadway decreases by 4.3 %. The failure range of the roof and two sides of the 12.2m long anchor cable is larger than that of the 9m anchor cable and the 10m anchor cable. The main reason is that the 12.2m anchor cable penetrates into the roof aquifer, which leads to the aggravation of water seepage and the further softening of the surrounding rock of the roadway. When the combined support of ' 9.2m long anchor cable + 4.2m short anchor cable ' is used, the surrounding rock damage and water seepage of the roadway are significantly reduced compared with the previous support parameters. Compared with the 10 m anchor cable with the smallest damage range in the first three support schemes, it is reduced by 37.5 %. According to the results of physical similarity simulation and numerical simulation experiment, the combined support method of ' 9.2 m long anchor cable + 4.2 m short anchor cable ' is proposed. The field application shows that the subsidence of roadway roof is obviously reduced, and the deformation and failure of roadway surrounding rock are effectively controlled.

     

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