The hard roof difficult to collapse easily causes gas accumulation, which threatens the production safety of coal mine. Therefore, roof pre-cracking is required. Although blasting and hydraulic fracturing can also crack the roof, blasting can easily induce rock bursts, whereas hydraulic fracturing needs complex equipment. In contrast, soundless cracking demolition agents (SCDAs) with noise-free, dust-free, and safe characteristics have obvious advantages. The main component of SCDA is calcium oxide, which reacts with water to produce higher expansion pressure. In this paper, focused on the angles of the borehole, the effect of SCDA is analyzed by numerical simulation based on Pingdingshan coal mine. The research results showed that the azimuthal angle α (between borehole projection and the roadway direction) does not significantly affect the efficacy of SCDAs, whereas the influence of borehole elevation angle β is far more significant than that of the azimuthal angle. Therefore, the angle β is a dominant factor influencing the effect of SCDAs. Based on different effects of SCDAs at different angle of boreholes, the weakening unit was established, so the SCDAs could give full play to roof fracturing. Moreover, field tests validated the importance of borehole angle on weakening the hard roofs.

难以塌陷的坚硬顶板容易引起瓦斯积聚，危及煤矿的生产安全。因此，需要屋顶预裂。尽管爆破和水力压裂也会使屋顶破裂，但爆破很容易引起岩爆，而水力压裂则需要复杂的设备。相比之下，具有无噪声，无尘和安全特性的无声裂化拆除剂（SCDA）具有明显的优势。SCDA的主要成分是氧化钙，它与水反应产生更高的膨胀压力。本文针对钻孔角度，以平顶山煤矿为例，通过数值模拟分析了SCDA的影响。研究结果表明，方位角α（在井眼投影和巷道方向之间）不会显着影响SCDA的效果，而井眼仰角β的影响远比方位角的影响大。因此，角度β是影响SCDA效果的主要因素。根据SCDA在不同钻孔角度下的不同影响，建立了弱化单元，使SCDA能够充分发挥顶板压裂的作用。此外，现场测试证实了钻孔角度对弱化坚硬顶板的重要性。