采动岩层渗透率与应力耦合关系数值模拟研究
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摘要
根据上覆岩层在采动条件下渗透率随应力变化的分布特点,建立了渗透率-应力模型,并通过fish语言将渗透率-应力模型镶嵌到FLAC3D软件,对采动条件下上覆岩层的渗透率与应力变化规律进行了模拟,同时以渗透率变化来判定采动卸压带的高度。结果表明:岩层采动后,渗透率随应力增大而减小;卸压带高度随开采距离增加而增加,但最后却趋于某一恒定值;开采保护层能很好地增强被保护层煤岩层的渗透性,能有效提高被保护层瓦斯抽采效率;被保护层开采后,其采空区上覆岩层的渗透率是保护层开采时上覆岩层渗透率的3倍左右。
A new model is established to describe the relationship between permeability and stress according to the distribution characteristics of overlying rock permeability with the stress change under mining-induced condition.The permeability-stress model,through the fish language,is embedded into the FLAC3D software to simulate the change law between permeability and stress of the overlying strata.At the same time,the permeability change is used to determine the height of the pressure relief zone.Numerical results show that the permeability decreases with the increase of stress;the pressure releasing height increases with the increase of the mining distance,but the final value tends to a constant value;the protective layer can enhance the permeability of the coal layer,and can effectively improve the efficiency of gas drainage;after being protected by the protective layer,the permeability of the overlying strata in the mined area is about 3 times that of the overlying strata.
A new model is established to describe the relationship between permeability and stress according to the distribution characteristics of overlying rock permeability with the stress change under mining-induced condition.The permeability-stress model,through the fish language,is embedded into the FLAC3D software to simulate the change law between permeability and stress of the overlying strata.At the same time,the permeability change is used to determine the height of the pressure relief zone.Numerical results show that the permeability decreases with the increase of stress;the pressure releasing height increases with the increase of the mining distance,but the final value tends to a constant value;the protective layer can enhance the permeability of the coal layer,and can effectively improve the efficiency of gas drainage;after being protected by the protective layer,the permeability of the overlying strata in the mined area is about 3 times that of the overlying strata.
引文
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[3]徐涛,唐春安,宋力,等.含瓦斯煤岩破裂过程流固耦合数值模拟[J].岩石力学与工程学报,2005,24(10):1667-1673.
[4]张春会,赵莺菲,王来贵,等.采动煤岩渗透率演化模型及数值模拟[J].岩土力学,2015,36(8):2409.
[5]申林方,王志良,李邵军.基于格子博尔兹曼方法表征体元尺度土体细观渗流场的数值模拟[J].岩土力学,2015(S2):689-694.
[6]申林方,王志良,李邵军.基于土体细观结构重构技术的渗流场数值模拟[J].岩土力学,2015,36(11):3307.
[7]吴志伟,宋汉周.基于流-热耦合模型的土石坝渗流热监测研究[J].岩土力学,2015,36(2):584-590.
[8]郭建春,庄园,刘超.考虑非达西效应的酸蚀裂缝流场数值模拟[J].岩土力学,2015,36(11):3315-3321.
[9]陈曦,张训维,陈佳林,等.水位波动下非饱和心墙土坝体的渗流和稳定性[J].岩土力学,2015,36(S1):609-613.
[10]赵阳升.多孔介质多场耦合作用及其工程响应[M].北京:科学出版社,2010.
[11]周世宁,林柏泉.煤层瓦斯赋存与流动理论[M].北京:煤炭工业出版社,1996.