采场瓦斯运移的三维LBM仿真

3D simulation of gas migration in mining stope based on LBM

地下煤矿工作面上隅角瓦斯积聚并超限是煤矿生产的重大安全隐患。为了解瓦斯积聚规律及瓦斯积聚量,构建了采场统一的三维LBM仿真模型,并开发采场瓦斯运移的三维LBM仿真软件。采场由工作面和采空区2个流场组成,其中,瓦斯与大气混合气体在工作面流场中的运动为紊流运动,而在采空区内的运动为非均质多孔介质的渗流运动。采场统一的LBM仿真模型通过采用不同的松弛时间和平衡分布函数来体现2个流场的特征。由于采场结构复杂,为了提高运算效率,采用分块耦合算法将采场划分成多个块,各块独立并行计算,块与块之间通过耦合交换数据,最终实现整个采场瓦斯运移仿真。模拟实例表明,该方法可以模拟和分析采场瓦斯运移状况,并得到采场瓦斯运移的相关数据。同时也可以得到采场流线分布规律、速度变化规律和采空区瓦斯运移规律。

The main purpose of this paper is to introduce an approach of 3D simulation for the gas migration in mining stope based on Lattice Bohzmann Method （LBM）. As known, gas aggregation exceeding the safe limit at the upper comer of underground mining often resuits in mining pit explosion. Therefore, it is of great urgency to explore the regularities of gas migration in the mining stope better control and prevention of underground gas explosion disasters. In view of this, a 3D simulation model of gas migration in mining stope has been developed to study the principles and volumes of gas aggregation. Mining stope can be divided into two fields： a working face and a goaf field. Mixed air movement in mining stope is complicated and can be classified as turbulent flow at the working face and seepage movement within heterogeneous porous media at the goaf field. An u- nified simulation model is constructed based on LBM in which the characteristics of these two fields are reflected by different relaxation time and distribution functions. Because of the complicated structure of mining stope, blocks coupling algorithm is adopted in order to improve the efficiency of computing. In this algorithm, the mining stope is divided into many blocks. Every block is computed in parallel and the block data are exchanged through the coupled algorithms and finally the simulation of gas migration in whole stope is realized. A case study showed that this method is able to simulate and analyze the situation of gas migration in mining stope and obtain considerable data volume of gas migration such as speed and concentration of random time and location spot of the mining stope. Besides that, laws of streamtrace, speed and gas distribution of the mining stope can be clarified as well. This method provides an alternative method to reveal the laws and the volume of gas aggregation at upper comer and provides a basis for gas aggregation control.