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针对毛洞隧道稳定性问题,利用自编刚体平动运动单元上限有限元程序进行计算分析,获得了失稳临界系数γD/c的上限解图表及相应的刚性运动块体破坏模式。结果表明:(1)失稳临界系数γD/c随土体内摩擦角ф的增大而增大,随隧道埋深与直径比H/D的增加而减小;不过,H/D对γD/c的影响并不显著,特别是对于内摩擦角较大的情况。(2)刚体平动运动单元上限有限元所得隧道刚性运动块体破坏模式大致具有两组交叉滑动面的特征;随着土体内摩擦角ф增大,隧道横向破坏范围明显收缩,刚性块体间的相互错动更加显著;H/D对破坏模式的形态影响不明显,当H/D增大时,隧道横向的破坏范围增加。
Aiming at the problem of the stability of the moulded tunnel, the finite element program of the upper limit of the translational rigid-body motion unit is used to calculate and analyze the upper bound solution of the critical stability coefficient γD / c and the corresponding rigid-body failure mode. The results show that: (1) The critical instability coefficient γD / c increases with the increase of soil friction angle ф, and decreases with the increase of tunnel depth and diameter ratio H / D. However, The effect of c is not significant, especially for larger internal friction angles. (2) The failure mode of the tunnel rigid motion block resulting from the upper limit finite element of the rigid body translational motion unit generally has the characteristics of two groups of cross sliding surfaces. As the friction angle ф of the soil increases, the transverse failure range of the tunnel obviously shrinks, The mutual dislocation of the tunnel is more significant; H / D has no obvious effect on the morphology of the failure mode. As the H / D increases, the damage range of the tunnel in the horizontal direction increases.