煤层群重复采动卸压瓦斯储运区演化规律实验研究

Experimental study on evolution law of pressure relief gas storage and transportation area of repeated mining in coal seams

为进一步研究煤层群重复采动卸压瓦斯储运区动态演化规律,以贵州某矿16#、18#煤层开采工作面为背景,通过物理相似模拟实验,研究了煤层群重复采动后上覆岩层裂隙分布特征,明确了卸压瓦斯储运区演化规律,提出了相应的判别方法,并进行了工程应用。结果表明,实验矿井上层煤开采后,覆岩垮落带高度11 m、裂隙带高度53 m。工作面附近覆岩关键层形成的砌体梁结构与其下方岩层之间的离层裂隙成为卸压瓦斯储集的空间。当下层煤开采后,受重复采动的影响,垮落带和裂隙带高度分别为13和83 m。上下煤层之间存在关键层,在其下部仍会形成瓦斯储集空间,采动裂隙贯通后下煤层卸压瓦斯易沿着裂隙区通道向上运移至煤层间隔层关键层下的储集空间,再顺着上煤层冒落带内裂隙通道继续向上。此时,上煤层采动形成的瓦斯储集空间也将充满瓦斯成为抽采的重点区域。基于此,提出采动卸压瓦斯储集空间判别方法,并在贵州某矿进行了抽采验证,抽采效果良好,保证了工作面的安全生产。

In order to further examine the dynamic evolution of the pressure relief gas storage and transportation area of the coal seams after repeated mining,with the mining face of the 16#and 18#coal seam in Guizhou as the background,the overburden after repeated mining was studied through physical similar simulation experiments.The distribution characteristics of rock cracks have clarified the evolution law of pressure relief gas storage and transportation areas,and the corresponding discrimination methods have been proposed and applied in engineering.The results show that after mining the upper coal in the experimental mine,the overburden caving zone is 11m high and the fracture zone 53 m high.The key layer of overlying rock near the working face forms a separation crack between the masonry beam structure and the rock below it becomes a space for pressure relief gas storage.When the lower coal is mined,the heights of the caving zone and fracture zone affected by repeated mining are 13 m and 83 m,respectively.There is a key layer between the upper and lower coal seams,and there will still be a gas storage space in the lower part.After the mining cracks are penetrated,the pressure-relieving gas in the lower coal seam will easily migrate upwards along the channel of the fracture zone to the storage space under the key layer of the coal seam,and then follow the crack channel in the upper coal seam caving zone to continue upward.At this time,the gas storage space formed by the mining of the upper coal seam will also be filled with gas and become a key area for drainage.Based on this,a method for discriminating the gas storage space of mining pressure relief gas was proposed,and the drainage verification was carried out in a mine in Guizhou,which turned out to be effective,and the safe production in the working face was ensured.