Response analysis of the excavation of a deep foundation pit for a metro station in soft soils

Abstract: We present a slightly abridged and adapted translation of the report “Response analysis of the excavation of a deep foundation pit for a metro station in soft soils” by Chinese geotechnical engineers (Wu et al., 2019). This report was presented in 2019 at the International Conference on Advances in Civil Engineering, Energy Resources and Environment Engineering in Jilin (China). It was also published as an article in the journal “Earth and Environmental Science” by the publishing company of the British scientific society “Institute of Physics” (IOP) that is now virtually international. It is an open access article under the CC BY 3.0 license that allows it to be distributed, translated, adapted, and supplemented, provided that the types of changes are noted and the original source is referred to. In our case, the full reference to the original paper (Wu et al., 2019) used for the presented translation is given in the end. The whole process of the construction of a deep foundation pit for a subway station in Ningbo soft soil area was modeled using the PLAXIS finite element software on the basis of the HS (Hardening Soil) constitutive model. A comparative analysis of the obtained simulation results and field monitoring data was carried out. The analysis indicated that the numerical simulation results could be well fitted to the field monitoring data. It was proved that the PLAXIS model on the basis of the HS constitutive model could perform the numerical simulation analysis of complex foundation pit excavation in a soft soil area very well. According to the monitoring data and calculated values, the horizontal displacements of the retaining wall (diaphragm wall) and surface settlements, which were caused by the excavation of the auxiliary foundation pit, were small and had little effect on the main foundation pit. It was proved that the construction method of the foundation pit support system for the considered project could control the influence of the excavation of the auxiliary foundation pit on the main foundation pit very well.

Keywords: soft soils; complex pit; retaining system; retaining wall; diaphragm wall; horizontal displacements; surface settlements; finite element modeling; hardening soil; model; field monitoring; comparative analysis.