磨砂射流轴向切顶技术防冲机理及效果研究

Research on the mechanism and effect of sandblasting jet axial roof cutting technology for rock burst prevention

  • 摘要: 磨砂射流轴向切顶技术为近些年开发的新技术,其防冲机理研究还不够明确。以大海则煤矿20101工作面为工程背景,采用理论分析和现场实测等方法,分析了采取磨砂射流轴向切顶技术前后覆岩空间结构特征,研究切顶对厚硬岩层能量聚集和侧向支承压力分布规律影响,揭示了磨砂射流轴向切顶技术防冲机理。结论如下:① 采取磨砂射流轴向切顶技术后,顶板岩层裂隙增多,致使顶板短边断裂线向前移动,减小或消除了悬臂作用,降低了切顶区域下方的静态支承压力,与此同时,切顶后顶板及时垮落并对上位岩层进行支撑,减少了上位岩层能量聚集和来压产生的动载压力,从而降低了冲击危险;② 采用瞬变电磁探测仪和统计疏水孔排水速度方法对切顶前后顶板视电阻率和排水速度进行探测和统计,以评估切顶效果。结果表明,切顶后高位岩层视电阻率显著升高,低位岩层视电阻率局部升高,与此同时疏水孔平均排水量为0.88 m3/h,提高了1.47倍,表明切顶后高低位岩层含水率显著降低,排水速度加快,顶板裂隙明显增加,切顶效果良好;③ 20101工作面微震和支架阻力监测结果表明:采用磨砂射流轴向切顶技术后,端头顶板及时垮落未出现悬顶作用,支架循环末阻力明显增大,微震事件总能量、总频和大能量事件频次分别下降56.50%、63.02%和33%,微震事件沿走向方向距工作面煤壁增大了30 m、倾向方向频次减少,顶板破裂高度从145 m降至75 m。

     

    Abstract: Sandblasting jet axial roof cutting technology has been developed in recent years, but its mechanism for rock burst prevention is not yet fully understood. Based on the work at the 20101 face of the Dahaize Coal Mine, theoretical analysis and field measurements were used to analyze the spatial structural characteristics of the overlying strata before and after the application of the sandblasting jet axial roof cutting technology. The impact of roof cutting on the energy accumulation in thick hard rock layers and the distribution of lateral support pressure was studied, revealing the mechanism of rock burst prevention of the sandblasting jet axial roof cutting technology. The conclusions are as follows: ① The application of sandblasting jet axial roof cutting technology increases the fractures in the roof strata, causing the short-edge fracture line of the roof to move forward, reducing or eliminating the cantilever effect, and lowering the static support pressure beneath the roof cutting area. At the same time, the roof collapses promptly after cutting, providing support for the overlying strata, reducing the energy accumulation in the upper strata and the dynamic load pressure generated by the roof weight, thereby reducing the risk of rock bursts. ② Using transient electromagnetic detectors and statistical methods to measure the drainage speed of desorption holes, the apparent resistivity and drainage speed of the roof before and after cutting were detected and statistically evaluated. Compared to before cutting, the apparent resistivity of the upper strata significantly increased after cutting, while the apparent resistivity of the lower strata increased locally. Meanwhile, the average drainage rate of the desorption holes increased to 0.88 m3/h, a 1.47-fold increase, indicating that the water content in both the upper and lower strata significantly decreased, the drainage speed increased, and the fractures in the roof significantly increased, demonstrating good cutting effectiveness. ③ Microseismic and support resistance monitoring results at the 20101 face show that after the application of sandblasting jet axial roof cutting technology, the end roof collapsed promptly without forming a cantilever. The end-cycle support resistance increased significantly, while the total energy, total frequency, and high-energy event frequency of microseismic events decreased by 56.50%, 63.02%, and 33%, respectively. Additionally, the distance of microseismic events from the working face coal wall increased by 30 meters along the strike direction, and the frequency decreased in the dip direction. The roof fracture height reduced from 145 meters to 75 meters.

     

/

返回文章
返回