煤巷掘进工作面煤与瓦斯突出预测的“掩护罩”理论

Role of shelter theory in forecasting coal and gas outbursts at the coal tunnel excavation faces

为了解决煤巷掘进工作面煤与瓦斯突出预测(以下简称"突出预测")的理论计算问题,首先,根据突出事故发生的一般规律和现行的突出预测方法建立了突出预测的物理模型,提出了突出预测的"掩护罩"理论,对瓦斯压力、地应力、煤的力学性质等在突出预测中的作用进行定性分析,提出了瓦斯压力起主要作用的观点;在此基础上,以瓦斯渗流理论为基础,建立了"掩护罩"不失效的临界条件——迎头内瓦斯压力的临界值与几何参数、煤的剪切强度等指标之间的定量关系,包括掘进过程中失效和延时失效两种情况,可以解释延时突出现象;最后,提出了需进一步研究的问题,包括快速获得迎头内瓦斯压力、煤体剪切强度指标的方法,以及非线性渗流偏微分方程线性化处理的误差问题。

This paper takes it as its target to solve the theoretical calculation problem for forecasting the likely outbursts at the coal tunnel excavation faces. For this purpose, we have set up first of all a physical model for forecasting the coal and gas outburst on the basis of the general characteristic features of the accidents that have taken place ever before with the methods available for the time being both at home and abroad so as to create a new concept of protective shelter. And, secondly, we have done a qualitative analysis of the effects of the gas pressure, gravity and the shear force of the coal-gas seam in the process of coal and gas outburst, in hoping to point it out that the process of the outburst takes place just due to the extremely high gas pressure. Afterwards, we have managed to make a detailed exploration of the non-failure criteria for the shelter, i.e. the quantitative relation between the maximum gas pressure allowable and the geometrical parameters in addition to the shear force of the coal, etc. at the coal tunnel excavation front based on the approximate mathematical solution of 1-D non-linear flow equation. The cr/teria we have gained can be applied to explain the instantaneous and/or delayed outburst accidents in the coal production. Finally, problems for further studies, including the fast determination of the gas pressure and the coal shear strength in the working faces, have been briefly mentioned along with the error analysis for the linear treatment to the non-linear partial differential equation of the fluid in porous media, etc.. However, this paper is mainly focused on the theoretical discussion of the problem, which is expected to win the at- tention and consultation interest from the experts concerned.