煤层开采过程中上覆岩层裂隙演化规律研究

Study on the fissure evolution law of overlying strata during mining

以淮南煤矿典型工作面为例,采用离散元数值软件UDEC(universal distinct element code)对工作面回采过程中上下煤岩体内应力场的变化及直接顶冒落过程进行了模拟,分析了上覆煤岩体裂隙产生、发展的形成过程,得到了上覆煤岩裂隙演化规律。研究结果表明,倾向方向工作面回采后,上覆煤岩体内产生冒落、裂隙带和离层带,在工作面内上角位置产生O型圈裂隙带,裂隙发育最大高度为45 m。煤层走向回采方向得到了初期来压步距约50 m,周期来压步距约20 m,上覆煤岩体裂隙在采空区上方约呈45°角发展,并随工作面的前进由下向上、由后往前依次演变。该结果对于煤与瓦斯共采中瓦斯抽放钻孔方位的布置具有工程指导意义。

A typical mining face of the Huainan mining area was taken for example,and the puking of the nether roof was simulated by UDEC（universal distinct element code）.The stress field and the development of overlying coal fissure were monitored and analyzed by the numerical model.The fissure evolution law was obtained through numerical simulation.The results showed that,after stoping,the caving zone,fractured zone and separation zone appeared in overlying coal,and the O-ring fracture zone developed on the upper side of the acting surface,of which the maximum height was 45 meters.The strike model study showed that the first presses pace was 50 meters,and the period presses pace was 20 meters.The fissures of overlying coal expanded at a 45-degree angle above goaf,which developed from down to up and moved forward continuously with the advancing mining.This conclusion will give some help for determining borehole location of gas extraction.