College of Safety Science and Engineering, Liaoning Technical University, Huludao, 125000, Liaoning, China.
Key Laboratory of Mine Thermodynamic Disasters and Control of Ministy of Education, Liaoning Technical University, Huludao, 125000, China.
Sci Rep. 2023 Jun 6;13(1):9199. doi: 10.1038/s41598-023-36464-y.
To determine the characteristics of air leakage concerning a "Y" type ventilation in gob-side entry retaining with roof cutting, pressure relief, and the law of a resulted gas accumulation (GA), research is conducted by employing the CFD simulation incorporated with the gauged parameters of working face (WF) mining to analyze the air leakage of "Y" type ventilation. For this purpose, the 1201 fully mechanized coal mining face in the south Wu mining location of the Daxing coal mine is taken as an illustrative example to study the air leakage in the "Y" type ventilation. So, the gas concentration (GC) issue surpassing the limit in the upper corner of the goaf was simulated. The results show that the goaf is formed into an open space when roof cutting and pressure relief technology along the goaf is implemented. The air pressure at the upper corner of the WF would be the lowest, which is only 1.12 Pa. The airflow of air leakage under a pressure difference would move from the gob-side entry retaining to the goaf. Moreover, the simulation of mine ventilation indicates that the volume of air leakage positively correlates with the length of gob-side entry retaining. When the WF is advanced 500 m ahead, the maximum volume of air leakage would reach 247 m/min within the range of 500-1300 m, and then the rate of air leakage gradually would decrease. When the WF is advanced at 1300 m, the air leakage would become the smallest, which is 175 m/min. When gas control is under consideration, the effect of gas extraction would be best with the buried pipe whose depth and diameter are set to 4.0 m and 400 mm, respectively. So, the GC in the upper corner would become 0.37%. After the high-level borehole with a 120 mm diameter is mined, the GC in the deep goaf decreased to 3.52%, and the GC at the upper corner became further reduced to 0.21%. While the high-level borehole gas is extracted by employing the extraction system of the high-concentration gas, the extraction system of low-concentration gas is utilized to extract the upper corner gas of the WF, thus, the problem of gas overrun was resolved satisfactorily. During the recovery period of the mining, the GC at each gauging point was less than 0.8%, which effectively guided the secure production in the Daxing coal mine and provided a theoretical foundation to control gas overrun during the mining process.
为了确定沿采空区切顶卸压沿空留巷“Y”型通风的漏风特性和由此产生的瓦斯积聚（GA）规律，采用 CFD 模拟与工作面（WF）实测参数相结合的方法，对“Y”型通风漏风进行研究。为此，以大兴煤矿南五采区 1201 综采工作面为例，研究“Y”型通风漏风。因此，模拟了采空区上隅角瓦斯浓度（GC）超限问题。结果表明，沿采空区切顶卸压技术形成采空区为开放空间，工作面上部角空气压力最低，仅为 1.12 Pa。在压差作用下的漏风气流将从沿空留巷流向采空区。此外，矿井通风模拟表明，漏风体积与沿空留巷长度呈正相关。当 WF 向前推进 500 m 时，在 500-1300 m 范围内，最大漏风体积可达 247 m/min，然后漏风率逐渐降低。当 WF 推进到 1300 m 时，漏风最小，为 175 m/min。考虑瓦斯治理时，埋管深度和直径分别设置为 4.0 m 和 400 mm，抽采效果最好。因此，上隅角 GC 会变为 0.37%。当直径为 120mm 的高位钻孔开采后，深部采空区 GC 下降到 3.52%，上隅角 GC 进一步下降到 0.21%。利用高浓度瓦斯抽采系统抽采高位钻孔瓦斯时，利用低浓度瓦斯抽采系统抽采工作面上部角瓦斯，从而较好地解决了瓦斯超限问题。在回采期间，各测点的 GC 均小于 0.8%，有效指导了大兴煤矿的安全回采，为采动过程中瓦斯超限治理提供了理论基础。
