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根据大采高工作面采空体积大及其矿压活动特点,将工作面覆岩分为直接顶内有结构岩层和无结构岩层两类,考虑采空区冒落矸石自重压缩和结构岩层失稳向采空区施加荷载,建立了两类结构不同开采阶段冒落带动态分布方程,揭示了采空区冒落带动态分布特征。结果表明:大采高工作面覆岩采空区冒落带呈明显的动态变化特征;冒落带高度变化与覆岩结构岩层厚度、容重、工作面开采时间、冒落矸石初始碎胀系数及压缩模量相关;基本顶砌体梁结构破断前冒落带在短时间内急剧增大,并达到极值,该阶段冒落带矸石自重压缩增加了采空高度使冒落带进一步增加;基本顶砌体梁结构回转载荷和直接顶内结构岩层滑落失稳施加的动荷载,对采空区矸石压缩作用受岩层厚度、容重及持续时间决定;整体下沉阶段冒落带高度随开采时间的增加而缓慢下降,一定时间后趋于稳定。
According to the large mined-out face and the characteristics of its underground pressure, the overburden strata are divided into two types: direct top-structured rockfill and non-structural rockfill. Considering the self-weight compression of the falling waste rock and the loss of structural rock strata in the goaf, Steady load applied to the goaf, the dynamic distribution equations of caving zone in two types of mining structures with different mining stages were established, and the dynamic distribution characteristics of the caving zone in the goaf were revealed. The results show that the caving zone of the mined-out area has obvious dynamic change characteristics in the big mining height working face. The height of the caving zone changes with the thickness of the overburden rock, the bulk density, the mining time of the working face, Compressive modulus. Before the rupture of the basic masonry beam structure, the caving zone increases sharply in a short time and reaches the extreme value. At this stage, the weight of the caving gangue increases by the self-weight compression and further increases the caving zone; And the dynamic load applied by the rock-slide instability of the directly overhead structure is determined by the rock thickness, bulk density and duration of the rock mass. The height of the caving zone during the whole subsidence phase varies with the mining time Increase slowly and slowly, after a certain period of time tends to be stable.