Undrained basal stability of braced circular excavations in non-homogeneous clays with linear increase of strength with depth

Braced circular excavations are commonly used as one of effective retaining structures in practice. Despite a number of studies in the past on the stability of this problem, its stability solution under the framework of lower bound limit analysis is very rare in the literature. The present study focuses on the stability analysis of braced circular excavations in non-homogeneous clays using the lower bound finite element limit analysis under ax-isymmetric conditions. The stability number of the problem is comprehensively investigated, and is affected by depth-radius aspect ratios of excavation, depth ratios of rigid base, and strength gradient factors. The influence of these dimensionless parameters on the predicted failure mechanisms are discussed and compared. The presented new lower bound solutions of braced circular excavations in non-homogeneous clays are useful for an accurate, convenient and reliable stability assessment of the problem in practice.