瓦斯压力对煤体应力及失稳破坏特性影响分析  

Analysis of the influence of gas pressure on coal stress and instability failure characteristics

作　　者：张士岭[1,2] 和树栋 ZHANG Shiling;HE Shudong(Gas Research Branch,CCTEG Chongqing Research Institute,Chongqing 400037,China;State Key Laboratory of the Gias Disaster Detecting,Preventing and Emergency Contolling,Chongqing 400037,China)

机构地区：[1]瓦斯灾害监控与应急技术国家重点实验室,重庆400037 [2]中煤科工集团重庆研究院有限公司瓦斯研究分院,重庆400037

出　　处：《采矿与安全工程学报》2022年第4期847-856,共10页Journal of Mining & Safety Engineering

基　　金：国家重点研发计划项目(2018YFC0808305)。

摘　　要：为探索渗流场下煤体应力分布及失稳破坏机制,借鉴土力学流土、管涌理论,基于达西定律与煤体渗流试验,对渗流场中瓦斯压力的作用形式、性质、大小进行了研究,进而建立了煤体一维渗透破坏机制。通过渗流-固体耦合作用下工作面煤体应力场分析,得出煤体失稳破坏时地应力、瓦斯压力和煤体力学性质共同作用的力学模型,并进行了数值模拟验证。结果表明:渗透力是瓦斯压力作用在煤体的重要形式,是一种体积力,反映的是单位体积煤体所受到瓦斯流的推动和拖拽力,作用方向及量纲与瓦斯压力梯度一致。工作面煤壁是最易发生渗透破坏的位置,其渗透破坏所需瓦斯压力与采掘空间气压、降压区长度、煤体黏聚力乘积的0.5次方成正比,与煤厚和孔隙率乘积的0.5次方成反比。由于渗透力的作用,工作面煤壁产生拉应力,瓦斯压力为3 MPa时,拉应力超过0.4 MPa。煤体失稳破坏时瓦斯压力、地应力发挥作用大小随空间变化,越靠近煤壁,瓦斯压力作用越大,瓦斯压力梯度达到一定值后甚至占据主导作用;远离煤壁,瓦斯压力作用减小,地应力占据主导作用。In order to explore the stress distribution and instability failure mechanism of the coal under the gas seepage field, referring theories of fluid soil and piping in soil mechanics and based on Darcy’s law and coal seepage tests, the action form, character and size on the gas pressure in the coal seepage field were studied. The one-dimensional coal seepage failure mechanism was established. Through the analysis of the coal stress field in the working face under the coupling action of seepage and solid, the relationship equations among the earth stress, gas pressure and the mechanical properties of the coal mass under the limit equilibrium state are obtained. And through the above equations and numerical simulations, the following conclusions are drawn. Seepage force, which is a kind of volume force, is an important form of gas pressure acting on coal. The direction and dimension are consistent with gas pressure gradient. The coal wall of the working face is the location where seepage destruction is most likely to occur. The gas pressure required for seepage destruction is proportional to 0.5 power of the product of mining space air pressure, length of pressure drop zone and coal location, while it is inversely proportional to 0.5 exponentiation of the product of coal thickness and porosity. Due to the effect of permeability, tensile stress is generated on the coal wall of the working face. When the gas pressure was 3 MPa, tensile stress exceeded 0.4 MPa. When the coal body is destroyed, the gas pressure and ground stress will change with space. The closer to coal wall, the greater the gas pressure effect, and the gas pressure gradient even takes the leading role after reaching a certain value. The farther away from the coal wall, the gas pressure will decrease and the ground stress will take the leading role.

关 键 词：渗透力 瓦斯压力梯度 煤与瓦斯突出 力学模型 渗透破坏 

分 类 号：TD315[矿业工程—矿井建设]