Liu Jun, Zhang Luwei, Wei Yanzhao, Wu Zeping
School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China.
Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Jiaozuo 454003, China.
ACS Omega. 2021 Dec 6;6(50):34920-34930. doi: 10.1021/acsomega.1c05574. eCollection 2021 Dec 21.
Most coal mine field application processes are carried out using empirical formulas because of the insufficient understanding of the fracture development law of the static blasting technology. This lack of understanding results in poor coal seam gas extraction. In this study, a stress-damage coupling model was established to investigate the construction parameters of the static blasting technology using COMSOL simulation software. Then, a stress-damage-seepage coupling model was designed to study the evolution of the fracture field (seepage field) during the static blasting process using realistic failure process analysis simulation software. Finally, the influencing factors and fracturing effects were analyzed comprehensively. The research results show the following. (1) Comparing the simulation results with previous field tests reveals that the seepage law of the numerical simulation of the static blasting technology is consistent with the field test results, verifying the rationality of the stress-damage-seepage coupling model. (2) The development of coal seam fractures is affected by the expansion pressure, elastic modulus, and guide hole arrangement; the guide hole arrangement can play a role in guiding the development direction of fractures and enhancing the effect of fracturing. (3) The coal body mainly experienced the following five stages of fracturing: coal body compaction, microdamage formation, microfracture formation, large fracture formation, and fracture propagation. In addition, because of the rapid release of soundless cracking agents during the large fracture formation stage, the gas flow decreased in a short time. (4) The static blasting technology causes the coal seam permeability coefficient to increase. Compared with conventional extraction, the effective influence radius in the horizontal direction increases by 5.1 times, and the effective influence radius in the vertical direction increases by approximately 3 times. The static blasting technology can increase the number of coal seam fractures and significantly reduce the coal seam gas pressure, thereby enhancing coal seam permeability and realizing safe coal mining.
由于对静态爆破技术的裂隙发育规律认识不足，多数煤矿现场应用过程采用经验公式进行。这种认识不足导致煤层瓦斯抽采效果不佳。本研究利用COMSOL模拟软件建立应力-损伤耦合模型，研究静态爆破技术的施工参数。然后，利用真实破坏过程分析模拟软件设计应力-损伤-渗流耦合模型，研究静态爆破过程中裂隙场（渗流场）的演化。最后，综合分析影响因素和压裂效果。研究结果如下：（1）将模拟结果与以往现场试验对比可知，静态爆破技术数值模拟的渗流规律与现场试验结果一致，验证了应力-损伤-渗流耦合模型的合理性。（2）煤层裂隙发育受膨胀压力、弹性模量和导向孔布置的影响；导向孔布置对引导裂隙发育方向、增强压裂效果有作用。（3）煤体主要经历煤体压实、微损伤形成、微裂隙形成、大裂隙形成和裂隙扩展五个压裂阶段。此外，在大裂隙形成阶段由于无声破碎剂的快速释放，气体流量在短时间内下降。（4）静态爆破技术使煤层渗透系数增大。与传统抽采相比，水平方向有效影响半径增大5.1倍，垂直方向有效影响半径增大约3倍。静态爆破技术可增加煤层裂隙数量，显著降低煤层瓦斯压力，从而提高煤层渗透率，实现煤炭安全开采。
