采空区裂隙岩体动态网络特性及其对气体渗流控制机制研究

In order to reveal the evolution mechanism of coal spontaneous combustion and methane coexisting hazards in goaf from the view of network structure and its perspective on gas seepage control, take the typical U mining face as the typical research object, firstly an equal ratio working face mining model is established by using discrete element software and stepwise excavation method is used to simulate the mining process. The spatial-temporal evolution rule of porosity in goaf is obtained. Three dimensional reconstruction and reverse engineering technology are used to construct the fracture network model of equivalent goaf in different mining periods. Fractal theory is applied to quantitatively characterize the degree of fracture development in different locations. Then the three-dimensional gas seepage experimental system of goaf is built to simulate the fracture failure and seepage environment of the goaf, and analyze the gas seepage and temperature evolution law of goaf under different air supply volume, different mining period and different heat sources. Finally, COMSOL software to read the PFC simulation results of porosity is realized , proposed goaf seepage zone of fracture network and gas seepage control model based on thermodynamics, and compared to the model simulation results with the physical experiment and numerical classification of mined out space area of coal spontaneous combustion and gas coupling hazard area, provide a theoretical basis for the for the analysis and prevention of goaf coal spontaneous combustion and gas coupling disaster spatial characteristics.

为了从网络结构及其对气体渗流控制角度揭示采动作用下采空区煤自燃与瓦斯耦合灾害形成机理，以典型U型开采工作面为研究对象，首先利用离散元软件建立等比例工作面开采模型，采用分步开挖方法模拟工作面开采过程，得到采空区孔隙率时空演化规律，并采用三维重建和逆向工程技术构建不同开采时期等价采空区裂隙网络模型，采用分形理论对不同位置裂隙发育程度进行定量表征；然后建立采空区三维气体渗流实验系统，模拟采空区裂隙破坏与渗流环境，分析不同供风量、不同开采时期、不同热源情况下采空区气体渗流和温度演化规律；最后，实现COMSOL多场耦合软件对PFC模拟孔隙率结果读取，提出基于渗流-热力学的采空区裂隙网络与气体渗流控制作用模型，并结合物理实验和数值模拟结果对比对模型进行修正，划分采空区煤自燃与瓦斯耦合灾害空间危险区域，为采空区煤自燃与瓦斯耦合灾害空间特性分析和防治提供理论依据。

采动覆岩裂隙网络对采空区气体运移规律具有显著影响，为提高深部高地压高地温矿井煤自燃与瓦斯耦合灾害等热动力灾害防治的针对性和有效性，本项目通过理论分析、实验室实验、相似材料实验和数值模拟相结合的方法，分析了关键层位置对裂隙网络发育影响，完善了煤岩体宏细观参数校正和赋值流程，提出了采动覆岩裂隙网络构建方法，分析了基于DEM-CFD的采空区煤自燃与瓦斯耦合危险区域快速识别技术，开发完善了采空区煤自燃与瓦斯耦合灾害动态隔离系统防治体系，并提出了隔离参数的确定方法，研发适用于该技术的凝胶泡沫材料。主要研究内容和创新成果如下：.首先，选择典型煤自燃与瓦斯灾害共生矿井，完成了不同关键层位置采动覆岩裂隙网络发育表征，利用相似材料模型对结果进行了验证，探讨了基于孔隙率发育结果的采动覆岩渗透分区划分方法；其次，完成了典型地区煤岩体采取和分析工作，通过取芯机在块煤和岩石上钻取原煤煤芯和岩芯，制成圆柱体标准试件，型煤利用取原煤后的煤块制成，进行煤岩体单轴压缩和巴西劈裂实验和预置裂隙煤岩破坏特性分析，结合物理力学实验和数值模拟结果，进而完善PFC模型细观力学参数赋值及校正流程，结合数值模拟结果、数字重建技术，提出了采动覆岩裂隙网络模型构建方法，并对模拟结果的分形特性进行分析；完成了采空区三维气体运移规律物理实验平台构建；最后，完成了采空区煤自燃与瓦斯耦合热动力灾害的快速识别与预测预警方法研究，阐述了采动覆岩裂隙网络对气体渗流的控制机制，对采空区煤自燃与瓦斯耦合共生灾害协同防治技术进行研究，对动态隔离参数进行了完善，并研发了对应的凝胶泡沫材料，为该类灾害防治提供保障。