围压效应下煤岩强度及破坏特征的数值模拟
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摘要
为了研究围压对煤岩强度和破坏特征的影响,对围压效应进行了理论分析,并利用FLAC2D模拟不同围压下煤岩的破坏情况。研究表明:煤岩极限破坏强度随围压的增大而增加,二者之间呈非线性关系;煤岩的轴向应力也随围压的增大而逐渐增大,应力区呈锥形和倒锥形分布,锥角大约为60°煤岩的切应力也随围压的增大而逐渐增大,剪切带也逐渐增大,从单重剪切发展到多重剪切;煤岩破坏的角度随围压的增大而逐渐增大;在没有围压时,煤岩外表面更容易达到塑性屈服状态;围压增大后,煤岩屈服后的塑性强化效果显著,符合幂次强化模型;煤岩的屈服极限也随围压的增大而逐渐增大。
In order to investigate the effect of confining pressure on coal strength and failure characteristics,the confining pressure effect was analyzed theoretically and simulated by FLAC2D.It shows that ultimate strength of coal enlarges with increasing confining pressure,and ultimate strength and confining pressure has a nonlinear relationship;axial stress enlarges with increasing confining pressure.The stress area presents taper distribution and reverse taper distribution,cone angle of which is about 60°.Shear stress and shear zone all enlarge with increasing confining pressure.Shear zone develops from single shear to multiple-shear;the rupture form of coal changes with the changing confining pressure.The angle enlarges with the changing confining pressure;the surface of coal more easily achieves the plastic yield state if no confining pressure loaded.Plastic hardening has a remarkable effect on the post-yield coal with increasing confining pressure.It accords with power strengthen model.Yield limit of coal also gradually enlarges with increasing confining pressure.
In order to investigate the effect of confining pressure on coal strength and failure characteristics,the confining pressure effect was analyzed theoretically and simulated by FLAC2D.It shows that ultimate strength of coal enlarges with increasing confining pressure,and ultimate strength and confining pressure has a nonlinear relationship;axial stress enlarges with increasing confining pressure.The stress area presents taper distribution and reverse taper distribution,cone angle of which is about 60°.Shear stress and shear zone all enlarge with increasing confining pressure.Shear zone develops from single shear to multiple-shear;the rupture form of coal changes with the changing confining pressure.The angle enlarges with the changing confining pressure;the surface of coal more easily achieves the plastic yield state if no confining pressure loaded.Plastic hardening has a remarkable effect on the post-yield coal with increasing confining pressure.It accords with power strengthen model.Yield limit of coal also gradually enlarges with increasing confining pressure.
引文
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[2]张流,薛丽霞,施良骐,等.高围压下岩石破坏和摩擦滑动过程中的声发射活动性[J].岩石力学与工程学报,1990,9(1):38-47.
[3]张流,王绳祖.固体围压介质下岩石三轴实验装置的压力标定[J].地震地质,1982,4(4):69-79.
[4]张流,王绳祖,王光根,等.高温高压岩石三轴实验装置(固体传压介质)及实验技术[J].力学与实践,1982,4(4):36-40.
[5]张流,王绳祖,施良骐.我国六种岩石在高围压下的强度特性[J].岩石力学与工程学报,1985,4(1):10-19.
[6]陈忠辉,傅宇方,唐春安.岩石破裂声发射过程的围压效应[J].岩石力学与工程学报,1997,16(1):65-70.
[7]A.Г.艾鲁尼,B.A.鲍宾,A.A.高尔曼洛夫.饱含瓦斯煤体微结构发展机理[J].矿业安全与环保,1987,14(6):46-49.
[8]林伯泉.含瓦斯煤体变形和渗透特性的实验研究[D].徐州:中国矿业学院,1986.
[9]姚宇平.含瓦斯煤的力学性质[D].徐州:中国矿业大学,1987.
[10]许江,鲜学福,杜云贵,等.含瓦斯煤的力学特性的实验分析[J].重庆大学学报,1993,16(5):42-47.
[11]徐涛.煤岩破裂过程固气耦合数值试验[D].沈阳:东北大学,2004.
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