Taking a foundation pit in Beijing as the background

the fast Lagrangian analysis of continua in 3 dimensions (FLAC3D) numerical calculation program and Mohr-Coulomb constitutive model are adopted to make analysis of the deformation and force condition of pile-anchor supporting system on the case of deepening excavation of the existing foundation pit. Calculation results show that the deepening excavation will induce poor bending performance of pile

larger horizontal displacement of supporting structure and failure of anchor system based on the existing supporting scheme. In order to ensure stability of the foundation pit

increasing pile fulcrum is necessary. Several reinforcement schemes are compared on the basis of design change and construction condition. The scheme of increasing anchor cable is adopted to reinforce the foundation pit. The mechanical behavior of foundation pit after deepening excavation with above supporting scheme is analyzed by using numerical simulation. The calculated deformation of foundation pit and supporting system is compared with field monitoring data; and the result shows that the scheme is reasonable. So the research results are of significance as a reference for similar engineering.