巨厚松散砂砾岩覆盖层下倾斜煤层巷道矿压显现规律研究

    Study on mine pressure behavior law of inclined coal seam roadway under great thick and loose sandy conglomerate overburden

    • 摘要: 针对浅埋巨厚砂砾岩覆盖层下巷道矿压显现异常的问题,以新疆乌苏市某矿巨厚砂砾岩覆盖下倾斜煤层巷道作为研究对象,探讨了不同岩性覆盖层下巷道围岩载荷差异特征,通过理论分析、数值模拟揭示了巷道对巨厚砂砾岩层载荷的矿压显现响应机制。研究结果表明:巨厚松散砂砾岩覆盖下巷道围岩应力包括覆盖层自重荷载和侧方覆盖层运移区域的附加荷载,当覆盖层强度越低,内摩擦角越小,覆岩的运移角和运移面积越大,施加给巷道围岩的附加载荷越高;巷道开挖后顶板巨厚覆盖层会形成“漏斗形”应力降低区,而倾斜煤层巷道开挖后“漏斗形”应力降低区表现出非对称性;巨厚松散砂砾岩覆盖层下方80~100 m范围内,巷道受松散层应力转移作用明显,不同岩性覆盖层下围岩应力存在差异性,巨厚松散砂砾岩相较于巨厚砂岩层峰值应力增高了1.19 MPa,且巷道距离巨厚松散砂砾岩覆盖层80 m相对距离9 m时塑性区面积和顶板位移量分别减少了86.55%、97.79%,当巷道与覆盖层距离超过80~100 m后,此时覆岩自重对巷道围岩受力影响开始显现,围岩应力、塑性区和顶板位移量随埋深增加逐渐增长;浅埋巷道受自重应力和附加载荷叠加影响,其中附加载荷由巨厚砂砾岩层滑移面积决定,需通过加强巷道顶板支护强度以控制巨厚砂砾层的滑移角和滑移面积;巷道支护优化后,其顶底板的相对移近量约为70 mm,两帮相对移近量约为130 mm,整体支护效果较好,未出现矿压显现情况。

       

      Abstract: Aiming at the abnormal mine pressure behavior of roadway under shallow buried great thick sandy conglomerate overburden, the inclined coal seam covered by thick sandy conglomerate in a mine in Wusu City, Xinjiang was selected as the research object, and the load difference characteristics of roadway surrounding rock under different lithologic overburden conditions were discussed. Through theoretical analysis and numerical simulation, the response mechanism of roadway to the load of thick sandy conglomerate was revealed. The results show that: the stress of roadway surrounding rock under the cover of extremely thick and loose sandy conglomerate includes the self-weight load of overburden and the additional load of lateral overburden migration area. When the strength of overburden is lower, the internal friction angle is smaller, the migration angle and migration area of overburden are larger, and the additional load applied to roadway surrounding rock is higher; after the excavation of the roadway, the great thick overburden of the roof will form a “funnel-type” stress reduction zone, while the “funnel-type” stress reduction zone shows asymmetry after the inclined coal seam roadway excavation; in the range of 80 m-100 m below the great thick and loose sandy conglomerate overburden, the roadway is obviously affected by the stress transfer of the loose layer. There are differences in the stress of surrounding rock under different lithologic overburden conditions. The peak stress of the great thick loose conglomerate increased by 1.19 MPa compared with that of the extremely thick sandstone layer, and the plastic zone area and roof displacement are reduced by 86.55 % and 97.79 % respectively when the roadway is 9 m away from the 80 m relative distance of the great thick sandy conglomerate overburden. When the distance between the roadway and the overburden exceeds 80-100 m, the influence of the overburden weight on the stress of the surrounding rock of the roadway begins to appear. The stress of surrounding rock, plastic zone and roof displacement increase gradually with the increase of buried depth. The shallow buried roadway is affected by the superposition of self-weight stress and additional load, in which the additional load is determined by the slip area of the great thick and loose sandy conglomerate layer. It is necessary to control the slip angle and slip area of the great thick and loose sandy conglomerate layer by strengthening the roof support strength of the roadway. After the optimization of the roadway support, the relative displacement of the roof and floor is about 70 mm, and the relative displacement of the two sides is about 130 mm. The overall support effect is better, and there is no mine pressure appearance.

       

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