基于渗透失稳机理的煤与瓦斯突出过程和控突措施作用机制分析

基于流固耦合理论，提出煤与瓦斯突出属渗透失稳的观点，把临界失稳梯度作为煤体的抗失稳强度指标。通过对突出过程中瓦斯压力梯度变化规律的分析认为：把瓦斯压力梯度达到临界失稳梯度的降压区的煤体视为一个“失稳分层”，突出是煤体以“失稳分层”的形式向前推进的过程，而每个“分层”的失稳表现为“整体性”失稳：延期突出是煤层瓦斯压力梯度逐渐增加并最终达到临界失稳梯度的结果；突出形成的”口小腹大”的孔洞形状．是突出发生过程中流场形态发生变化所致。并将控突措施的作用机理分为4类：降低煤层瓦斯压力、增大巷道气压背景值、延长降压区宽度和提高煤体临界失稳梯度。

Coal and Gas Outburst Process and Controlling Measures Action Mechanism Analysis Based on Seepage Instability Mechanism

Based on liquid-solid coupling theory, a concept of coal and gas outburst is a kind of seepage instability has been put forward, and takes the critical instability gradient as the coal mass instability-resistant intensity index. The analysis of gas pressure gradient variation during outburst process considered that： regarding the coal mass in a depressed area with the gas pressure gradient arrives at critical instability gradient as an ＂instability unit＂, the outburst is a process of coal mass as a form of ＂instability unit＂ pushing forward, while the instability of each ＂unit＂ appears as ＂integral＂ instability. Postponed outburst is a result of coal seam gas pressure gradient gradually increasing and finally arrives at critical instability gradient. ＂Urn-shaped＂ pore space formed by outburst is caused by flow field configuration diversification during the outburst bobbed up process. The action mechanism of outburst controlling measures can be classified into 4 kinds： lowering down coal seam gas pressure, increasing roadway gas pressure background value, extending depressed area width and boosting coal mass critical instability gradient.