In this study, closed-form solutions are presented for two classical problems: the load exerted on strip or circular trapdoors and the stability of tunnel headings in purely cohesive soils, considering both the case of a constant undrained shear strength and of a linear vertical strength profile. The solutions are based on a minor modification of Gunn's lower-bound plasticity solution. According to comparative numerical stress analyses and finite-element limit analyses, the proposed equations accurately estimate trapdoor loads and face support pressures in soils with uniform strength, while they are slightly conservative in the case of depth-dependent shear strength. Thus, they are appropriate for the assessment of the stability of underground structures in saturated, low-permeability soils subjected to short-term loading and exhibiting depth-dependent strength – which, so far, has only been possible numerically.

中文翻译：

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重新审视不排水活板门和隧道掌子面稳定性

在这项研究中，针对两个经典问题提出了封闭形式的解决方案：施加在条形或圆形活板门上的载荷以及纯粘性土壤中隧道掘进的稳定性，同时考虑了恒定不排水剪切强度和线性垂直强度的情况轮廓。这些解决方案基于对 Gunn 的下界可塑性解决方案的微小修改。根据比较数值应力分析和有限元极限分析，所提出的方程准确地估计了具有均匀强度的土壤中的活板门荷载和面支撑压力，而在与深度相关的抗剪强度的情况下，它们略微保守。因此，它们适用于评估地下结构在饱和状态下的稳定性，