This paper deals with the determination of upper and lower bounds for the three-dimensional undrained stability of shallow tunnels. The tunnel is circular and a distance between its face and its lining is considered. The soil shear strength is modeled using the Tresca criterion. Results of the upper and lower bounds of the stability number are presented, for several geometrical and resistance configurations and their comparison with previous results is made, showing the clear improvement obtained. Finally, equations approaching the stability number are proposed.

中文翻译：

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浅埋隧道三维不排水稳定性的上下限

本文探讨了浅埋隧道三维不排水稳定性的上限和下限的确定。隧道是圆形的，并考虑了其表面与衬砌之间的距离。使用Tresca准则对土壤抗剪强度进行建模。给出了几种几何构型和阻力构型的稳定性数上下限的结果，并与以前的结果进行了比较，显示出明显的改进。最后，提出了逼近稳定数的方程。