断层应力状态对煤与瓦斯突出的控制
Stress control for coal and gas outburst on a fault plane
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摘要: 在建立断层面受力模型的基础上,通过断层面正应力和孔隙压力关系分析影响断面附近煤与瓦斯突出的关键参数,重新定义封闭系数并引入剪切指数概念,以此判断断层的封闭性及结构稳定性。研究发现,正应力大小与断层走向锐夹角正相关,而切应力与走向锐夹角关系取决于最大、最小水平应力和与正应力比值; 在断层附近发生煤与瓦斯突出,依据断层结构参数和应力场差异,瓦斯压力存在极值条件,结合构造煤分布及瓦斯压力与正应力关系将其分为两大模式:流压控制型(FPC)和流-固耦合型(FSC),并通过一个具体案例证实断层应力状态对煤与瓦斯突出的控制。Abstract: A mathematical model is developed to describe the stress state of a fault plane. The control factors for coal and gas outburst near the fault are identified using the relationship between section normal stress and shear stress. The sealing coefficient is redefined and the concept of shear index is introduced to judge sealing ability of the fault and its structural stability. The study shows that the magnitude of normal stress is positively correlated with the acute angle between the fault strike and the maximum horizontal principal stress. However, it is not always between the magnitude of shear stress and the acute angle, which depends on the maximum/minimum horizontal principal stress and the normal stress. When certain intensity is satisfied, the gas pressure is a premise condition for the coal and gas outburst near the fault. Combined with the deformed coal distribution, according to the restrict relationship between gas pressure and normal stress in the fault, the coal and gas outburst are classified into 2 types: flow pressure controlling (FPC) and fluid solid coupling (FSC). An engineering case is employed to validate the stress control for the coal and gas outburst on the fault plane.