干砂地层中盾构开挖面失稳模式及土拱效应试验研究

Model test study of the failure mechanism of shallow tunnels in dry sands

盾构开挖面的稳定直接关系到盾构施工的安全,而国内外关于开挖面失稳模式的大型模型试验研究却很少。利用直径1m的盾构模型,对干砂地层中盾构开挖面稳定性问题进行了研究。通过对开挖面前方土体应力状态变化的监测,从土体应力变化的角度,揭示了随着土拱的形成、发挥和发展过程,开挖面经历了局部失稳和整体失稳这样一个渐进破坏的模式。将试验结果和楔体模型计算结果进行对比,对计算模型参数的选取提出了建议。

A large-scale model test on the face stability of shield tunneling is conducted in dry sand with the shield diameter 1m.By monitoring the change of the stress state in front of the face,the formation and development of soil arching is identified,and the collapse occurs in two stages： local instability and global instability.Comparing the test results to the wedge model calculation results,the values of the model parameters are proposed.