深部倾斜煤层采动底板破坏演化特征分析

为研究深部倾斜煤层底板破坏特征及破坏深度,以羊东煤矿8469工作面为研究对象,采用理论分析、数值模拟和现场实测相结合的方法,对煤层采后底板应力分布规律、塑性区发育特征及破坏深度进行了研究。通过数值模拟与理论分析可知:煤层开采后,作用在周围煤岩体上的支承压力产生不同的应力分区。沿煤层走向方向,应力呈对称性变化,形状近似马鞍状,在工作面两端处产生应力集中;沿煤层倾向方向,倾斜剪切力的存在使底板岩体由采动破坏转变成滑移破坏,塑性破坏区和应力变化大致呈勺型分布形态,最大应力集中区出现在工作面下侧。随着工作面向前推进,底板破坏范围相应增大,但推进255m后,破坏深度不再增加。现场实测表明,底板浅部岩层最早受到扰动,且受到的扰动程度最高。扰动范围随最大注水量的减少而增加,在底板下25m范围内的岩层受影响较小。由此可知,该工作面底板破坏深度为25.0～29.2m。

Analysis on evolution characteristics of mining floor failure in deep inclined coal seam

In order to study the floor failure characteristics and depth of deep inclined coal seam floor. Taking 8469 working face of Yangdong coal mine as the research object, the stress distribution pattern, plastic zone development and failure depth are analyzed by using the methods of theoretical analysis, numerical simulation and field measurement. Through numerical simulation and theoretical analysis, it can be seen that after the coal seam mining, different stress zones are generated by the supporting pressure acting on the surrounding rock mass and coal seam. Along the strike direction of coal seam, the stress changes symmetrically, whose shape is similar to "saddle", and stress concentration occurs at both ends of the working face; As for dip direction, under the action of inclined stress, the floor mining failure will be transferred to slip failure. The plastic failure zone and stress disturbance are approximately a "spoon shaped", and the maximum stress concentration area appears at the lower side of the working face. With the working face advancing forward, the failure area of the floor increases correspondingly, but the failure depth does not increase after 255 m. Field testing showed that the shallow strata of the floor was disturbed earliest and most affected. The range of disturbance increases with the decrease of the maximum water injection, and the rock strata in the range of 25 m below the bottom plate are less affected. From these methods, it is concluded that the failure depth of the coal seam floor is 25~29.2 m.