Undrained trapdoor and tunnel face stability revisited

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