大倾角大采高煤矸互层顶板失稳规律及对支架的影响

为研究大倾角大采高煤矸互层顶板失稳规律及对支架的影响,以新疆焦煤集团2130煤矿25213工作面为研究对象,采用物理相似模拟实验、Rhino+Kubrix+FLAC 3D相结合的数值模拟及现场实测的方法,深入分析了大倾角大采高工作面不同夹矸层数、厚度下煤矸互层顶板失稳规律与顶板-支架相互作用特征。结果表明,煤矸互层顶板破坏是由于倾斜中部、靠近支架的煤线先产生局部压剪破坏,随之向附近软煤夹层、夹矸扩展,导致顶板非均衡破坏,诱发架前冒顶、煤壁片帮等现象。大倾角大采高煤矸互层顶板工作面支架工作阻力、顶板最大主应力及顶板变形均呈明显的非对称性,且随着夹矸层数增加,支架上方煤矸顶板集中应力影响范围、围岩变形影响范围及塑性破坏范围均有所增大。煤矸互层顶板支架与围岩有顶板与支架正接触、破断顶板作用于支架掩护梁、架间相互作用等3种作用特征。较一般顶板的大倾角工作面,煤矸互层顶板对支架作用力明显减小,支架工作阻力整体呈倾斜中、下部大于上部的特征;支架非对称受载表现为前柱侧向载荷大于后柱,但随夹矸厚度的增加,顶梁受载程度趋于均布化。结合研究结果,提出了缩短空顶时间、分区域控制、超前预爆破及工作面实时矿压监测等一系列大倾角大采高煤矸互层顶板稳定性控制措施,其中,重点控制工作面倾斜中部煤矸互层顶板的稳定性,来保证工作面的安全高效生产。

Instability law of the coal-rock interbedded roof and its influence on supports in large mining height working face with steeply dipping coal seam

In order to study the instability law of the coal-rock interbedded roof and its influence on supports at large mining height working face in steeply dipping coal seam,the 25213-working face of Xinjiang Coking Coal Group 2130 coal mine is taken as the research object,the instability law of the roof and the interaction between the roof and supports under different layers and thickness coal-rock interbedded roof of steeply dipping coal seam are analyzed by means of physical similarity simulation experiments,numerical analysis combined with Rhino,Kubrix and FLAC 3D,and field monitoring.The results show that the failure of coal-rock interbedded roof is caused by the partial compression shear failure of interbedded coal first,and then spread to the adjacent soft coal interbedded and gangue,which leads to the unbalanced roof failure and induces roof caving and rib spalling.The working support resistance,roof maximum principal stress and roof deformation have obvious asymmetry characteristics in steeply dipping coal seam under coal-rock interbedded roof.With the increase of the number of gangue layers,the range of concentrated stress,surrounding rock deformation and plastic failure of coal-rock interbedded roof above the supports are increased.There are three interaction characteristics between supports and surrounding rock,namely,positive contact between roof and supports,broken roof acting on support shield beam,and the interaction between supports.Compared with the general roof in steeply dipping coal seam,the acting force of coal-rock interbedded roof on the support is significantly reduced.The support working resistance under coal-rock interbedded roof is asymmetrical,generally,the inclined middle and lower part is larger than the upper part of working face.The supports are asymmetrically loaded,and the lateral load of the supports’front leg are greater than the back leg.However,with the increase of the coal gangue roof thickness,the loading degree of the top beam tends to be uniformly distributed.Based on the research results,in order to ensure safe and efficient production of working face,a series of control principles for the stability of the steeply dipping coal seam under coal-rock interbedded roof are put forward,such as shortening the time of the empty-support,regional control,advance blasting and real-time dynamic monitoring of working face rock pressure.