浅埋煤层非充分垮落采空区下重复采动致灾机理

This project is setting up on the background of disaster mechanism of closed-up mining under the shallow non-fully collapsed gob. Focusing on the unknown bearing characteristics of broken rock mass in the shallow non-fully collapsed gob, difficult to evaluate the stability of coal pillar group, hard to determine the development regularity of crack network after repeated mining and etc. By using multi-dimensional research methods such as theoretical analysis, physical simulation, numerical calculation and field measurement, the characteristics of roof stability in the non-fully collapsed gob are revealed, finding out synergistic bearing characteristics of "pillars- broken rock mass", analyzing the propagation law of concentrated stress in the roof of the lower seam, then revealing the breaking rule of the lower seam roof and the formation mechanism of the impact load, building the model of cracks network after repeated mining and the flow characteristics of fluid in cracks, then, proposing the method for weakening dynamic load produced by roof collapsing of lower seam, providing the relevant theoretical support for the safety mining under the shallow non-fully collapsed gob.

本项目以浅部非充分垮落采空区下近距离煤层开采致灾机理为研究背景，针对非充分垮落采空区内破碎岩体承载特性未知，煤柱群稳定性难以评价，重复采动后覆岩裂隙网发育规律确定困难等特征，综合运用理论计算、物理模拟、数值计算及现场实测等研究手段，摸清非充分垮落采空区内顶板稳定特征，研究“煤柱群-采空区碎石”协同承载特性与集中应力在底板中传播规律，揭示下组煤顶板破断规律及冲击载荷形成机理，建立重复采动后覆岩中裂隙网分布模型，阐明流体在裂隙网中的流动特性，为浅埋煤层非充分垮落采空区下安全开采提供相关理论支持。

本项目以浅部非充分垮落采空区下近距离煤层开采致灾机理为研究背景，针对非充分垮落采空区内破碎岩体承载特性未知，煤柱群稳定性难以评价，重复采动后覆岩裂隙网发育规律确定困难等特征，综合运用了理论计算、物理模拟、数值计算及现场实测等研究手段。本项目主要研究了浅部非充分垮落采空区顶板稳定特征及空隙度分布规律、煤柱群长期承载特征及稳定性评价、采空区内破碎岩体承载特性及上覆集中载荷确定方法、集中载荷在底板中的传递规律与下组煤顶板破断特征和重复采动后覆岩中空隙演化规律及分布特征。得出了如下重要结论：①得到了间隔式采空区内顶板稳定特征及地表沉陷变形规律，揭示了破碎煤岩体孔隙结构变化特征和孔隙、喉道直径的变化规律；②建立了一维重整化煤柱群模型，评价了间隔式煤柱群的稳定性；③确定了采空区承载范围及承载特征表达式，得到了不同地貌下煤柱上覆集中载荷表达式；④确定了间隔式煤柱群下方应力集中深度，阐明了下煤层工作面顶板运移过程中动载形成机理；⑤揭示了非充分垮落采空区下重复采动前后的围岩裂隙发育规律，得出了非充分垮落采空区下重复采动围岩渗流特征。本项目的实施为浅埋煤层非充分垮落采空区下安全开采提供了相关理论支持，有效防控了非充分垮落采空区下重复采动可能面临的灾害。