Face stability model for rectangular large excavations reinforced by pipe roofing

Abstract

This paper presents a model for the analysis of the face stability of rectangular excavations supported by roof-box jacking (RBJ), which are recommended for underground passages in crowded urban spaces. The model is based on the limit equilibrium method, which takes into consideration the change in the overburden earth pressure acted on the sliding block due to the presence of the pipe roof. Elastic foundation beams are used to consider the mechanical action of the pipe roof. The proposed model is then used together with the finite element software ABAQUS for the analysis of a roof-box jacking excavation in Tianlin Road in Shanghai. The analyses show that the results of the proposed model are close to that of the finite element analysis and that this model could be used in engineering practices.