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顶板锚杆非均匀工作阻力对抗冲弱面影响及应用探讨

Discussion on the influence and application of non-uniform working resistance of roof anchors on the weak face of scouring

  • 摘要: 目前国内煤巷抗冲能力评价理论假定锚杆工作阻力均匀分布。根据现场实测,冲击危险煤巷的顶板锚杆工作阻力呈显著离散性。为研究巷道抗冲弱面与锚杆非均匀工作阻力的相关性,建立了顶板锚杆非均匀工作阻力下围岩临界应力和锚杆冲击吸收能量计算模型,得到了顶板不同位置临界应力和锚杆冲击吸收能量分布特征,与冲击地压发生的应力、能量条件结合分析,确定特定条件下发生冲击地压时率先破坏位置,据此提出了一种抗冲弱面划分方法。以典型冲击地压矿井−新巨龙煤矿6305运输巷为工程算例,结果表明:围岩临界应力、动载触发值与锚杆工作阻力呈正相关关系,锚杆冲击吸收能量与锚杆工作阻力呈负相关关系;在顶板锚杆非均匀工作阻力下,顶板各位置的临界应力、动载触发值、锚杆冲击吸收能量等呈显著差异。以超前工作面350.10,424.10 m运输巷为研究对象,根据已有类似研究成果,假设巷道顶板上方20 m有一2.5级震源,存在11个断面满足冲击地压发生的应力条件,动载扰动下易发生冲击地压。结合单元支架补强措施,计算得到顶板可承受5次方以上强矿震的冲击作用,满足局部防冲要求。基于《防治煤矿冲击地压细则》(2018)要求的区域−局部二级冲击地压危险评价体系,提出区域−局部−弱面三级危险评价方法,进行了应用探讨,有利于防控弱面冲击危险。

     

    Abstract: At present, according to the domestic evaluation theory of coal drift rock burst resistance capacity, assume that the working resistance of anchor rods is uniformly distributed. According to the site survey, the working resistance of roof anchor rods with the rock burst on the hazardous coal drift has presented the obvious discreteness. To study the correlation between the weak surface of the drift rock burst resistance and the non-uniform working resistance of the anchor rods, a calculation model of the critical stress of surrounding rocks and the rock burst energy absorbed by the anchor rods under the non-uniform working resistance of the roof anchor rods has been established, and the distribution characteristics of the critical stress and rock burst energy absorbed by the roof anchor rods on different positions have been obtained, which have been used to make analysis in combination with the stress in case of the occurrence of rock burst and determine the initial destruction position in case of the occurrence of rock burst under specific conditions. Therefore, a sort of rock burst weak surface classification method has been proposed. The typical rock burst coal mine - haulage drift No. 6305 of Xinjulong Coal Mine is taken as an engineering example. The results show that the critical stress and dynamic load trigger value of surrounding rocks are positively correlated with the working resistance of anchor rods, while the rock burst energy absorbed by anchor anchor rods is negatively correlated with the working resistance of anchor rods. Under the non-uniform working resistance of roof anchor rods, the critical stress, dynamic load trigger value and rock burst energy absorbed by anchor rods on each position of roof anchor rods present obvious differences. The 350.10, 424.10 m haulage drift of the advance working face is taken as a research object. According to the previous similar research results, assume that there is a Ms 2.5 seismic source located 20 m above the drift roof, and there are 11 sections that meet the stress conditions for the occurrence of rock burst. Therefore, it is found that the rock burst easily occur under dynamic load disturbance. In combination with the strengthening measures of the unit support, it is found through calculation that the roof can withstand the rock burst of more than 5 powers of strong mine earthquake and meet the requirements of local rock burst prevention. Based on the regional - local secondary rock burst risk assessment system required by the Rules for the Prevention and Control of Rock Burst in Coal Mines (2018), the three-level (namely, regional - local - weak surface) risk assessment method is proposed and discussed in application, which facilitates the prevention and control of weak surface rock burst risks.

     

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