煤层水压致裂后煤岩应力解析

Stress analysis on coal after hydraulic fracturing of coal seam

  • 摘要: 水压致裂后煤岩应力分布规律对水压致裂防冲效果起关键性作用。采用理论研究方法得出高压注水压致裂后及卸水后水区和气区的孔隙、瓦斯压力和煤体应力解析解。结果表明,致裂后水区孔隙压力沿径向变化不大,与注水压力接近;气区瓦斯压力沿径向呈递减趋势;在水区外围一定范围内形成瓦斯压力升高区;水区煤体环向应力将会减小,直到变为拉应力;气区煤体径向应力沿径向递减。卸水后水区孔隙压力、煤体径向应力沿径向呈递增趋势;气区煤体径向应力沿径向呈递增趋势,趋近于原始煤体应力;气区煤体环向应力沿径向呈递减趋势;气区孔隙压力沿径向呈递减趋势。这为煤层水压致裂预防冲击地压提供理论基础。

     

    Abstract: The law of coal and rock stress distribution after hydraulic fracturing plays a key role in the effect of scour prevention. the theoretical method was used to study the fracture distribution of water area and gas area, methane pressure and analytical solution of stress on coal seam after hydraulic fracturing and water pressure relief. Study shows that the pore pressure of water area changes little along the radial direction after hydraulic fracturing and is close to water injection pressure, gas pressure of gas area showes a decreasing trend along the radial direction. In a certain extent, the gas pressure rise area is formed in the periphery of the water area. The circumferential stress in the water area of the coal body will be reduced until it becoms tensile stress. Radial stress of coal body in gas area shows a decreasing trend along the radial direction. While after the water pressure is relieved, the pore pressure and radial stress of coal body in water and gas area both show a decreasing trend along the radial direction and the value of the radial stress of coal body in gas area is close to primary stress of coal body. The tangential stress and pore pressure of coal body in gas area shows a decreasing trend along the radial direction. All of the studies have provided the theoretical basis for using hydraulic fracturing to prevent rock burst.

     

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