Numerical analysis of one-strut failure in deep braced excavation considering anisotropic clay behavior

Abstract

In recent years, with the rapid development of braced excavation supported by multi-level struts, cases of continuous failure caused by local failure of braced excavation occur frequently. However, in previous studies, soil is usually idealized, and anisotropy is ignored, leading to a certain deviation in the results accuracy. Based on a subway braced excavation in Tianjin, this paper adopted the NGI-ADP soil constitutive model to consider soil anisotropy and established a 3D finite element model to simulate the one-strut failure (OSF) at different positions, which is regarded as the triggering factor for several progressive excavation failure case histories. The axial force response of support system after OSF was quantified by load transfer rate and load increase rate. The results showed that the influence of soil anisotropy on the struts axial force cannot be ignored. The response of the support system is similar when the one-strut fails in the middle of the same level struts. After OSF, there is a nearby load transfer phenomenon and mainly in the vertical direction.

Keywords

one-strut failure / braced excavation / anisotropy / NGI-ADP model / finite element analysis

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