巷道断层带瓦斯突出及防护岩柱临界厚度确定

Fault Gas Outburst in Roadway and Determination of Critical Thickness of Prevention Rock Pillar

矿井巷道在穿越含瓦斯断层或石门揭煤的掘进过程中,常常遇到岩石(煤)与瓦斯的超前突出。为科学地预留安全岩柱,通过深入分析各种突出影响因素,笔者修正了微元体中有效应力的表达式,从断裂力学的角度分析了岩柱内裂隙面上的应力状态,通过分析裂纹尖端周边的应力场,得出了裂纹尖端应力集中的力学成因,认为岩石(煤)与瓦斯突出是裂纹尖端应力强度因子达到岩体的断裂韧度时裂纹发生失稳扩展从而产生破坏的动力现象,并以此建立了岩柱临界安全厚度的计算模型。实践证明,计算得出的安全岩柱厚度与施工中的实际案例较为吻合。

Rock（coal） and gas pro-outburst always happen during the excavation process of mine in gascontaining fault zone or crosscut.In order to preserve the safe pillar scientifically,this paper analyzes various influencing factors in-depth,and modifics the expression of effective stress in micro unit,then analyzes the stress state of the surface of cracks in rock pillar from the view of fracture and damage mechanics.Mechanical causes of stress concentration at cracks tip can be get from the stress field around the cracks tip,that is,the rock（coal） and gas outburst is due to the cracks tip stress intensity factor reaches the fracture toughness of rock mass,then instable propagation occurs to cracks and resulting in destruction,and then calculation model of excavation can be cstablished based on above analysis.Practice shows that the safe thickness from calculation is about the same with the thickness in actual case under construction.