基于渗流-热动力耦合的采空区煤自燃基础研究

Based on the coupled characteristics of gas percolation and thermal dynamic, the laws of distribution and evolution, gas flow, concentration, temperature and oxidation zone, were revealed in the process of coal spontaneous combustion in goaf. By means of advanced analysis, such as XRD, FTIR, SEM, mercury porosimeter, then phase components, surface functional groups, micro structure, fracture channel and pore structure characteristics were analyzed after the actions of different temperature, and combined with stress and permeability test by MTS the coal permeability characteristics were evaluated, the coal permeability evolution equation with athermodynamic process was established; the gas coupling mechanism about seepage and thermal power was discussed, and then the hot air pressure mechanism and its influence in gas flow path and scope were revealed in the process of coal spontaneous combustion in goaf. Based on the gas nonlinear percolation-oxygen concentration distribution-heat transfer equation, multiphysics numerical simulation of goaf was done; then, based on the simulation experiment table of coal spontaneous combustion process in goaf, and verify the numerical simulation modeling.

为了从气体渗流与热动力耦合的角度揭示采空区煤自燃过程煤体微细观结构和物化组份变化特征，得到气体渗流场、浓度场和温度场的耦合分布和演化规律，本项目运用XRD、FTIR、SEM、压汞仪等先进的分析手段，分析不同热力过程作用后煤体物相组份、表面官能团、微细观结构、裂隙通道以及孔隙结构特征，结合MTS应力-渗透特性试验，研究不同热力过程作用后煤体的渗透特征，建立随温度变化的煤体渗透率演化方程；通过建立煤自燃过程气体升浮-扩散效应热力学模型，探讨气体渗流、传热与升浮-扩散热力学作用机理；基于流体动力学、传热学和热动力学理论，依据热动力参数与网络裂隙场、渗透率、渗透压的内在关系，建立渗流-热动力耦合的数学模型，模拟分析热动力作用对采空区多场耦合分布的影响规律；最后利用采空区煤自燃过程模拟实验系统进行有热源项和无热源项存在两种条件下的煤自燃模拟实验，对基于渗流与热动力耦合的数学模型进行验证。

为了揭示基于气体渗流与热动力耦合的采空区煤自燃规律，开展了不同温度煤样程序升温特性实验，运用XRD、FTIR、SEM、压汞仪等先进的分析手段，分析不同热力过程作用后煤体物相组份、表面官能团、微细观结构、裂隙通道以及孔隙结构特征；分析了采空区空隙和渗透率分布特征，建立了随温度变化的煤体渗透率演化方程；通过建立煤自燃过程气体升浮-扩散效应热力学模型，探讨气体渗流、传热与升浮-扩散热力学作用机理；基于流体动力学、传热学和热动力学理论，依据热动力参数与网络裂隙场、渗透率、渗透压的内在关系，建立渗流-热动力耦合的数学模型，采用FLUENT数值模拟软件模拟了采空区多场耦合分布规律；最后利用采空区煤自燃过程模拟实验系统进行有热源项和无热源项存在两种条件下的煤自燃模拟实验，对基于渗流与热动力耦合的数学模型进行验证。