急倾斜短壁综放采场围岩采动应力演化规律

Mining stress evolution law of surrounding rock in short wall fully⁃mechanized caving stope of steeply inclined coal seam

以新疆龙泉煤矿3⁃3c急倾斜煤层水平分段短壁综放开采为工程背景,通过物理相似模拟实验和数值计算相结合的研究方法,分析了多分段采场围岩变形破坏规律,量化表征了第一主应力大小、方向演化特征,揭示了采动应力传递演化机理,确定了急倾斜煤层短壁综放开采合理阶段高度。研究结果表明:急倾斜煤层短壁综放采场围岩应力传递路径呈非对称偏转特征,沿采空区上方顶板形成非对称应力包络拱,采空区倾斜中上部岩体应力释放,分段底部靠近顶板侧岩体应力集中。开采一分段至三分段过程中,顶板垮落高度与裂隙发育增幅较小,应力拱高度与采高比值相近,第一主应力集中峰值较小、应力偏转程度较低,多分段采场围岩结构稳定性较好。开采至四分段,顶板发生大面积垮落,垮落矸石冲击底板诱发滑移破坏,发生围岩大范围链式灾害,应力拱高度突增,拱高与采高比值增大。确定合理阶段高度为3个分段高度30 m左右,能有效防止围岩失稳突变诱发链式灾害,从源头消弭采场动力灾害的产生。

The horizontal sublevel short wall fullymechanized caving mining of 33c steeply inclined coal in Xinjiang,named as Longquan Coal Mine,is taken as the engineering background.By means of the combination of physical similarity simulation experiment and numerical calculation,the deformation and failure law of surrounding rock in multisublevel stope is investigated in detail and the evolution characteristics of the first principal stress size and direction is analyzed through quantitative characterization method.And the transmission and evolution mechanism of mining stress is revealed while the reasonable stage height of short wall fullymechanized caving mining of steeply inclined seam is also determined.The result can be concluded as follows:the stress transfer path of surrounding rock in steeply inclined short wall fullymechanized caving face is characterized as asymmetric deflection with the formation of asymmetric stress envelope arch along the roof above the goaf.And the stress of rock mass in the middle and upper part of the goaf is released while the stress of rock mass near the roof at the bottom of the subsection is concentrated.During the period of mining from the first section to the third section,the height of the roof caving and variation of fracture increase slightly while the value of stress arch height is close to the ratio of mining height.And the first principal stress concentration peak is small while the stress deflection degree is low.It turns out that the stability of surrounding rock structure of multisection stope is better.As the mining stage moves to the fourth section,a large area of roof caving collapse.Due to the impact of caving gangue,it leads to the occurrence of slip failure,a largescale chain disaster of surrounding rock,the rapid increase of stress arch height as well as the rise of arch height and the ratio of mining height.And its convincing that the reasonable stage height can be divided into three sections with the value about 30 m,which is of great benefit to the prevention of the chain disaster induced by the instability of sudden change of surrounding rock as well as the elimination of the occurrence of stope dynamic disaster from the start.