灵新煤矿地下水库煤柱坝体合理尺寸研究

Research on the reasonable size of coal pillar dam of underground reservoir in Lingxin Coal Mine

近年来,煤矿地下水库技术已成为西部地区保护和利用矿区水资源的重要手段,地下水库矿井水已成为西部地表生态灌溉的重要水源之一。以西部矿区灵新煤矿近距离倾斜煤层群采掘地质条件为工程背景,针对该矿首座煤矿地下水库建设过程中遇到的煤柱坝体留设问题,采用数值模拟的方法,分析了六采区工作面开采和水库储水压力两大因素对煤矿地下水库煤柱坝体的影响。研究表明:相关工作面回采后,会在煤柱坝体及邻近围岩中产生塑性区,随着煤柱坝体宽度的增加,煤柱坝体及附近围岩中塑性区相互贯通的趋势逐渐减弱。当煤柱坝体宽度增至50 m时,塑性区相互贯通的现象消失;当煤柱坝体宽度增加到60 m时,煤柱坝体及邻近围岩中的塑性区间距(塑性区未贯通区域)扩大至40 m左右。在储水压力作用下,煤柱坝体及邻近围岩中的塑性区裂隙将发生二次扩展,随着水压的增大,裂隙扩展长度逐步增大,在3 MPa水压(储水高度300 m)作用下塑性区裂隙扩展长度达到5 m左右。因此,为防止水力作用下煤矿地下水库透水灾害的发生,认为煤柱坝体合理尺寸应取60 m。

In recent years,coal mine underground reservoir technology has become an important means to protect and utilize water resources in mining areas in western China,and mine water from underground reservoir has become one of the important water sources for surface ecological irrigation in western China.On the basis of the geological conditions of mining and excavating of the close inclined coal seam group in Lingxin Coal Mine in the western mining area,aiming at the problems of the coal pillar dam in the construction of the first underground reservoir in the mine,the influences of the two factors of the mining face and the reservoir water pressure on the coal pillar dam of the underground reservoir in the coal mine were analyzed by numerical simulation.The study results showed that after mining of related working face,the plastic zone appeared in the coal pillar dam and the surrounding rock.With the increase of the width of the coal pillar dam,the trend of the plastic zone connecting with each other in the coal pillar dam and the surrounding rock gradually weakened.When the width of the coal pillar dam was 50 m,the phenomenon of the plastic zone connecting with each other disappeared;when the width of the coal pillar dam was 60 m,the distance between the unconnected plastic zones in the coal pillar dam and its adjacent surrounding rock expanded to about 40 m.Under the action of water storage pressure,the cracks in the plastic zones of the coal pillar dam and its adjacent surrounding rock would expand again.With the increase of water pressure,the crack expansion length increased gradually.Under the influence of 3 MPa water pressure(water storage height was 300 m),the crack expansion length in the plastic zone reached about 5 m.Therefore,in order to prevent the occurrence of water inrush disaster of underground reservoir in coal mine under hydraulic action,it was considered that the reasonable size of coal pillar dam should be 60 m.