断层-围岩系统的形成过程及快速回跳数值模拟
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摘要
采用 FLAC 模拟了断层-围岩系统的形成过程及位移的分布规律．计算中采用了莫尔-库仑与拉破坏复合的破坏准则,峰后岩石本构关系为线性应变软化．两条断层带(或剪切带)汇交时系统形成,之后其承载能力下降．在断层带左侧,由于在系统承载能力降低的过程中,弹性应变的快速恢复,出现了快速回跳现象(系统失稳)．在断层带之外,位移分布是均匀的．在断层带位置, 存在较大的位移梯度．系统承载能力越低,位移梯度越大．远离加载端的区域先回跳,然后回跳区域逐渐扩大,向加载端传播,直到整个系统都回跳．上述过程持续的时间步数较少,说明了系统失稳的突发性．系统整体回跳发生于应变软化阶段．
The formation process of the system composed of fault band and elastic rock block and the shear displacement distribution across a fault band were modeled numerically by FLAC.The adopted failure criterion was a composite Mohr-Coulomb criterion with tension cut-off and the post-peak constitutive rela- tion of rock was linear strain-softening.Once two shear bands combine to form a fault band,the system is formed,subsequently leading to the decrease in load-carrying capacity of the system.On one side of the fault band,snap-back occurs due to the sharp recovery of elastic strain in strain-softening process,indicat- ing the unstable failure.Nearly uniform displacement distribution is observed outside the fault band.A higher displacement gradient exists within the band and increases with the decrease in load-carrying capacity of the system.Snap-back of the zone far away from the loading end is the earliest.Then,the size of the snap-back zone propagating towards the loading end increases until snap-back of the entire system takes place.The process only needs a few time steps,reflecting the abrupt occurrence of instability of the sys- tem.Snap-back of the entire system occurs in the strain-softening stage of a stress-strain curve.
The formation process of the system composed of fault band and elastic rock block and the shear displacement distribution across a fault band were modeled numerically by FLAC.The adopted failure criterion was a composite Mohr-Coulomb criterion with tension cut-off and the post-peak constitutive rela- tion of rock was linear strain-softening.Once two shear bands combine to form a fault band,the system is formed,subsequently leading to the decrease in load-carrying capacity of the system.On one side of the fault band,snap-back occurs due to the sharp recovery of elastic strain in strain-softening process,indicat- ing the unstable failure.Nearly uniform displacement distribution is observed outside the fault band.A higher displacement gradient exists within the band and increases with the decrease in load-carrying capacity of the system.Snap-back of the zone far away from the loading end is the earliest.Then,the size of the snap-back zone propagating towards the loading end increases until snap-back of the entire system takes place.The process only needs a few time steps,reflecting the abrupt occurrence of instability of the sys- tem.Snap-back of the entire system occurs in the strain-softening stage of a stress-strain curve.
引文
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[10]王学滨，潘一山，马瑾．剪切带内部应变(率)分析及基于能量准则的失稳判据．工程力学，2003，20(2)：101
[11]王学滨，宋维源，黄梅，等．考虑水致弱化及应变梯度的断层岩爆分析．岩石力学与工程学报，2004，23(11)：1815
[12]王学滨，海龙，宋维源，等．断层岩爆是应变局部化导致的系统失稳回跳．岩石力学与工程学报，2004，23(18)：3102
[13]王学滨，潘一山，盛谦，等．动力应变局部化传播及尺寸效应数值模拟．计算力学学报，2002，19(4)：500
[14]孙吉主，唐春安．断层地震孕育的椭圆形区域及其前兆规律．地震，1996，16(4)：355
[15]唐春安，傅宇方，赵文．震源孕育模式的数值模拟研究．地震学报，1997，19(4)：337
[2]蔡美峰，孔广亚，贾立宏．岩体工程系统失稳的能量突变判断准则及其应用．北京科技大学学报，1997，19(4)：325
[3]唐春安，徐小荷．岩石破裂过程失稳的尖点突变模型．岩石力学与工程学报，1990，9(2)：100
[4]潘一山，王来贵，章梦涛，等．断层冲击地压发生的理论与试验研究．岩石力学与工程学报，1998，17(6)：642
[5]潘岳，刘英，顾善发．矿井断层冲击地压的折迭突变模型．岩石力学与工程学报，2001，20(1)：43
[6]李长洪，蔡美峰，乔兰，等．岩石全应力-应变曲线与岩爆的关系．北京科技大学学报，1999，21(6)：513
[7]王学滨，潘一山，任伟杰．基于应变梯度理论的岩石试件剪切破坏失稳判据及应用．岩石力学与工程学报，2003，22(5)：747
[8]Wang X B,Yang X B,Zhang Z H,et al.Dynamic analysis of fault rockburst based on gradient-dependent plasticity and energy criterion.J Univ Sci Technol Beijing,2004,11(1):5
[9]Wang X B,Dai S H,Hal L.Quantitative calculation of dissipated energy of fault rock burst based on gradient-dependent plasticity.J Univ Sci Technol Beijing,2004,11(3):197
[10]王学滨，潘一山，马瑾．剪切带内部应变(率)分析及基于能量准则的失稳判据．工程力学，2003，20(2)：101
[11]王学滨，宋维源，黄梅，等．考虑水致弱化及应变梯度的断层岩爆分析．岩石力学与工程学报，2004，23(11)：1815
[12]王学滨，海龙，宋维源，等．断层岩爆是应变局部化导致的系统失稳回跳．岩石力学与工程学报，2004，23(18)：3102
[13]王学滨，潘一山，盛谦，等．动力应变局部化传播及尺寸效应数值模拟．计算力学学报，2002，19(4)：500
[14]孙吉主，唐春安．断层地震孕育的椭圆形区域及其前兆规律．地震，1996，16(4)：355
[15]唐春安，傅宇方，赵文．震源孕育模式的数值模拟研究．地震学报，1997，19(4)：337
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