【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．更多还原

【Abstract】 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.更多还原