覆岩高位整层爆破卸压“人造预裂层”源头防治冲击地压技术体系及应用

Technology system and application of “artificial pre-fracture layer” by high level whole layer blasting for pressure releasing to source prevention and control of rockburst

  • 摘要: 主动卸压防冲是落实强化煤矿冲击地压源头治理的重要措施。现行的主动卸压防控方式,或采用回采工作面平巷布孔卸压,或采用井下原位水力压裂技术,具有卸压保护范围有限、卸压施工进度制约等不足;或采用地面水力压裂防冲系统,具有卸压范围广时效长等优点,也需要解决前期投入等。因此,秉持源头防治、防患未然、经济高效的一体化的防冲卸压创新战略思想,研究一种实践易行、效果显著、可全面推广的新型区域卸压源头防冲技术体系势在必行。提出了覆岩高位超前整层爆破卸压技术体系,针对可产生动载荷的较高位关键层,创新高位岩巷、高位钻场、爆破钻孔布置,将高位坚硬岩层超前、整体、均匀爆破预裂,从而形成“人造预裂层”。该方法突破了一般的长钻孔距离限制,使得岩层爆破的卸压高度、卸压范围、卸压效果均大幅提高,可形成覆盖整个工作面区域甚至多个工作面的超前工作面开采的高位“人造预裂层”。高位爆破“人造预裂层”首先使得该高位坚硬岩层的来压步距和来压强度大幅减弱,其次也缓冲减弱了其上硬岩层向下传递的矿山压力,最后还可降低其下方硬岩层的来压步距。在陕西长武亭南煤业3409工作面首次进行了覆岩高位整层爆破卸压“人造预裂层”技术试验后,现场实测效果表明采用该方法较之常规爆破卸压区域,支架的平均来压强度、来压步距、来压持续距离和压力报警频次均大幅减少;巷道深孔和浅孔应力也均减少;微震事件总能量、大能量微震事件大幅度减少,且密集程度显著降低,工作面中段的微震事件尤为稀疏;地音高能事件、震源CT获得的冲击风险区域也有减少,各种实测手段均验证了高位爆破人造预裂层卸压防冲技术的优越性。

     

    Abstract: Active pressure relief is an important measure for source controlling of rockburst in coal mines. The current active pressure relief prevention and control method, or using the arranging holes along the roadway of the mining face, or underground in-situ hydraulic fracturing technology, has some shortcomings such as limited pressure relief protection range and constrained by the progress of pressure relief operation. When a surface hydraulic fracturing prevention system is used, it has the advantages of a wide range long-term of pressure relief, but may have the problem of high early investment, etc. Therefore, adhering to the innovative strategic ideas for pressure relief to prevent and control rock burst, which is from the source, prevention and economic efficiency, it is imperative to propose a new type of regional pressure relief source prevention technology system that is easy to practice, significant in effect, and can be comprehensively promoted. This paper proposes a new pressure relief technology system for high level whole layer pre-blasting of overlying rock. To blast higher key layers that can generate dynamic loads, the innovative high level rock tunnels, high level drilling sites, and blasting drilling arrangements are used to evenly pre-crack high level entire hard rock layers in advance, thus forming an “artificial pre-fracture layer”. This method breaks through the general limit of long drilling distance, greatly improving the pressure relief height, range, and effect of rock blasting, and can form a high-level “artificial pre-fracture layer” that covers the entire working face area or even multiple working faces before mining. The “artificial pre-fracture layer” of high level blasting first significantly weakens the weighting distance and weighting strength of the high level hard rock layer. Secondly, it also cushions and weakens the mining pressure transmitted downwards by the hard rock layer above it. Finally, it can also reduce the weighting step of the hard rock layer below it. After conducting the first “artificial pre-fracture layer” technology test for high level blasting pressure relief of overlying rock at the 3409 working face of Tingnan coal mine, the on-site measurement results show that compared to conventional blasting pressure relief areas, the average pressure strength, pressure step distance, pressure duration distance, and pressure alarm frequency of the support are significantly reduced using this method. The stress in both deep and shallow holes of the roadway is also reduced. The total energy of microseismic events and high-energy microseismic events have significantly decreased, and the intensity has significantly decreased. Microseismic events in the middle section of the working face are particularly sparse. The burst risk area obtained from seismic source CT and the high energy AE events has also been reduced, and various actual measurement methods have verified the superiority of the artificial pre-fracture layer pressure relief prevention technology for high-level blasting.

     

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