煤壁矿压测定及其在沿空掘进中的应用

MINE PRESSURE MEASUREMENT IN COAL PILLAR AND ITS APPLICATION TO ROADWAY DRIVEN CLOSE TO GOAF

沿空掘巷是减少煤柱压煤,提高煤炭回收率的有效方法之一。在淮北、潞安、晋城等水文地质条件相对简单的矿井已经得到广泛应用,但是由于沿空掘巷的力学环境与一般的煤巷不同,矿压较高,维护困难。许多学者专门对此进行了研究,但很少有人对沿空掘巷围岩的矿压和位移进行长期观测。为此在刘桥二矿655工作面掘了一个专门巷道进行为期半年的观测。经观测发现,煤柱分为3个区:塑性变形区,煤壁内0～4 m;残余压力支承区,煤壁内4～10 m;原岩压力区,煤壁10 m以外的区域。观测还发现在塑性区,煤柱的矿压随时间在衰减,但衰减的速率随时间而减少,在采后146 d趋于稳定。由此可以确定沿空掘巷的位置应在煤柱0～4 m内,即小煤柱的尺寸不应大于4 m,掘巷的滞后时间不应小于146 d。这一研究结果在皖北矿区各矿的应用效果显著。

Roadway driving close to the goaf is one of the effective methods to reduce the non-mineable coal reserve confined in the pillar and to raise coal productivity. The method is widely applied in the coal mines with relative simple hydrogeological conditions, such as the coal mines in North Anhui Coal Field, Lu＇an Coal Field and so on. Because the stress condition in roadways close to goaf is rather different from the normal ones, the goaf roadways have high strata pressure and it is difficult to maintain. In order to solve the problems, many scholars have made site investigations by observation, numerical and physical simulations, and the structural analysis of the roof strata. But few long-term observations about mine stress and roof-floor closing displacement in the coal pillar, in which the goal roadways are planned to drive, are reported. To understand the stress and the displacement, a special appendix opening is driven from the roadway in work face 655, the Second Liuqiao Coal Mine： and the measurements were made for about 146 days. According to the observation, it is found that the pillar can be classified as 3 zones in stress conditions as follows： （1） the plastic zone, 0-4 m from the edge of the pillar; （2） the zone of abutment pressure on integrated coal, 4-10 m from the pillar; and （3） undisturbed zone, 10 m and above. In plastic zone, the strata pressure is reduced with time, and the reducing speed is attenuated with time to zero after 146 days when the coal was mined. The strata pressures in other zones remained high during the observation. Therefore, the suitable place for the goal roadway is seen in the plastic zone; and the pillar between the roadway and the goal should not be larger than 4 m and not be earlier than 146 days after the coal is mined. The achieved results are successfully used in the mines of northern part of Anhui Province.