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为了研究在非均匀收敛条件下浅埋隧道围岩塑性区的分布,进行了公式推导和理论分析,并采用有限元软件ABAQUS建立了隧道的有限元模型进行验证,并结合坡荣隧道的工程实际建立了ABAQUS有限元模型。探讨了5种变形模式的塑性区分布规律,并与建立的ABAQUS验证模型得出的塑性区分布进行对比分析。最后采用边界条件0(BC0)建立了坡荣隧道进口段的模型,并将模拟得到的地表沉降数值与实际监测所得数据进行对比。研究结果表明:其理论方法计算结果与ABAQUS计算结果塑性区具有相同的形态,但相对ABAQUS计算结果更为保守,塑性区范围稍大;采用非均匀收敛模式计算时,在拱顶均有最大塑性半径,而拱腰和拱底相对较小,对于不同的收敛模式,塑性半径计算值不同;采用均匀收敛模式计算时,拱底塑性区较大,拱顶塑性区最小,这种计算情况与实际隧道塑性区分布不符,因此仅仅考虑隧道周边均匀径向收敛不足以表述隧道的真实塑性分布情况。
In order to study the distribution of plastic zone of surrounding rock in shallow tunnel under non-uniform convergence conditions, the formula derivation and theoretical analysis were carried out. The finite element model of tunnel was established by finite element software ABAQUS to verify. Combined with the engineering practice The ABAQUS finite element model is established. The distribution of plastic zone in five deformation modes was discussed and compared with the plastic zone distribution obtained by the established ABAQUS validation model. Finally, the boundary condition 0 (BC0) was used to establish the model of the inlet section of the slope-wing tunnel. The simulated ground settlement values were compared with the actual monitored data. The results show that the calculated results of the theoretical method are the same as those of the plastic zone calculated by ABAQUS, but the results are more conservative than the ABAQUS calculation and the plastic zone is slightly larger. When using the non-uniform convergence mode, the maximum plasticity The radius of the arch and the arch bottom are relatively small, the calculated values of the plastic radius are different for different convergence modes; when the uniform convergence mode is used, the plastic area of the arch bottom is larger and the plastic area of the arch is the smallest. The distribution of plastic zone in the tunnel is inconsistent. Therefore, considering the uniform radial convergence around the tunnel is not enough to express the true plastic distribution of the tunnel.