大倾角大采高采场倾向梯阶结构演化及稳定性分析

Structural evolution of ladder roof and its stability analyses for a fully-mechanized working face with a large mining height in steeply inclined coal seam

以大倾角煤层长壁大采高采场为研究对象,运用数值模拟、相似材料模拟、现场实测和理论分析相结合的手段,揭示了大倾角大采高采场顶板结构形成与演化特征,分析了顶板结构与支架、煤壁及垮冒矸石的相互作用特征。结果表明:大倾角煤层大采高采场空间尺度较一般采高大倾角煤层采场大,垮落顶板向工作面倾斜下方滚、滑特征更为活跃,充填压实程度高,工作面倾斜中、上部顶板岩层破坏运动空间增大,易形成跨层位、大尺度、非对称的空间梯阶状岩层结构。其中,高位梯阶岩层结构周期性破坏具有强度大、步距小、周期短、有冲击性等特点,其对采场低层位岩层、支架和煤壁的稳定性有明显影响。该结构受到切向力和法向力共同作用,且具有拉伸、压剪和复合型失稳模式,易造成工作面倾斜上部支架受载多变、中上部高煤壁片帮。

Taking a longwall working face in the steeply inclined coal seam with a large mining height as the research object, research methods including the numerical simulations, the physical material simulations, field measurement and theoretical analyses are used to analyze the formation and evaluation of roof structure, the interaction among the roof structure, supports and coal face. Research results indicate that the strata movement rules of large mining height face are similar to those of a general mining height face in the steeply inclined seam. However, the space of mining area increases obviously, the rolling-sliding of caving roof is more often. The gob is filled and compassed more tightly. In the middle and top area of working face along the incline direction, the mined-out space becomes more bigger and the ladder roof structure can be formed which shows a cross-layer, big scale and asymmetry space structure. The periodic break of higher ladder structure has several characteristics as follows： strong strength, small step, short period and burst proneness. The higher ladder structure also affects the stabilities of lower strata, support and coal face. Such structure is forced by both the normal and tangential stress and has instability model such as the tensile, shear and compound, which also induces the changeable loading of support at the top of working face and the face failure at middle and top part.