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复杂顶板条件下切顶留巷关键技术研究

Research on key technology of gob-sideentry by roof cutting with complex roof condition

  • 摘要: 针对店坪矿切顶留巷初期挡矸,锚索和单体液压支柱等支护体失效导致的巷道报废的问题,采取了全巷道顶板岩性探测的方法,分析了试验巷道的复杂顶板条件下切顶留巷的关键问题。通过建立留巷围岩稳定结构及其受力模型,分析了切缝高度及岩石碎胀性对基本顶运动的影响规律、恒阻锚索对顶板的支护原理以及液压支柱对切缝侧顶板的剪切作用,指出留巷的顶板运动,从时间和空间上可分为直接顶垮落期、基本顶断裂下沉期和压实稳定期3个时期,恒阻锚索支护和留巷动压期支护的参数设计要以顶板运动最剧烈期为基础进行计算。给出了留巷的预裂切缝、恒阻支护和动压期临时支护等关键技术参数的理论公式,并结合巷道各段围岩特性,将试验巷道划分7个区间段,并分段优化了留巷的关键技术参数。通过对现场留巷门架压力数据分析,滞后工作面0~60m为直接顶垮落和基本顶周期性断裂阶段,顶板运动剧烈;滞后工作面60~160m为垮落矸石逐渐压实阶段,顶板运动缓慢;滞后工作面160m以后,留巷围岩变形逐渐趋于稳定。现场应用表明:分段优化前留巷顶底板和两帮累计变形量分别为1200mm和1420mm,巷道回缩率54%;采取分段优化后,两处变形分别控制在420mm和435mm以下,巷道回缩率在18%以下,留巷围岩变形控制效果良好。

     

    Abstract: In view of the problem of the roadway scrapping caused by the failure of the retaining bodies such as anchorage, anchor cable and single column in the initial stage of the gob-side entry retaining by cutting roof in Dianping Mine, the method of detecting the lithology of the roof of the roadway was adopted to analyze the key problems of the gob-side entry retaining by cutting roof under the complex roof conditions. By establishing the surrounding rock stability structure and its mechanical model, the influence of the cutting height of the cutting seam and the rock swell on the basic roof movement, the supporting principle of the NPR anchor cable to the roof and the shear action of the hydraulic prop to the roof on the side of the cutting seam were analyzed. It is pointed out that the roof movement of retaining roadway can be divided into three periods: direct roof caving period, basic roof fracture subsidence period and compaction stability period. The parameter design of the constant-resistance anchor cable support and the retaining dynamic pressure period support should be calculated based on the most intense period of roof movement. The theoretical formula of the key technical parameters, such as the pre-splitting of roof, constant resistance support and the temporary support during the dynamic pressure period were given. Combined with the surrounding rock characteristics of each section of the roadway, the experimental roadway was divided into 7 sections. The key technical parameters of the roadway were optimized.Through the analysis of the mine pressure data of the roadway on site, the top plate movement was severe in the 0~60 m lag working surface, and the roof movement was severe. The lag working surface was 60~160 m, which was the compaction of the fallen waste rock. At the stage, the roof movement was slow; after the lag working surface reached 160 m, the deformation of the surrounding rock gradually stabilized. The field application shows that the cumulative deformation of the roof and floor and two sides of the retaining roadway are 1 200 mm and 1 420 mm respectively at the initial stage, and the roadway retraction rate is 54%. After subsection optimization, those are controlled below 420 mm and 435 mm, the shrinkage rate is below 18%, and the effect of deformation control of surrounding rock is good.

     

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