Excavation in the Vicinity of an Anti-Flood Embankment—A Case Study

According to Polish law, it is prohibited to perform excavations or locate buildings closer than 50 m to an embankment. In order to obtain exemption from this ban, filtration and stability analysis of the embankments and excavation in flood conditions must be performed. This paper presents the results of a numerical investigation of a real case on the interactions between an excavation and an embankment. A transient flow model was used for filtration simulations, and the obtained pore pressure distributions automatically underwent stability analysis. The stability and filtration simulation results are presented. The safe design of an excavation support is proven. Changes in the values of the Stability Factor (SF) and stability loss mechanism (sliding surface location) during a flood are observed and discussed, with possible explanations given. A parametric study focused on the influence of the length and stiffness of the steel sheet pile wall on the embankment and excavation behavior. The relationship between wall length and the Stability Factor (SF) is strongly nonlinear and differs significantly between the various phases of flooding. Shortening of the wall may lead to either a decrease or increase in the bending moment. The main novelty of this work is the combination of excavation support and anti-flood embankment analysis, for which references are very limited. Also, the parametric study is considered novel, with no similar analyses being found in the literature. The problem of the reasonable selection of design values of the bending moment in the sheet pile wall is also often omitted. Additionally, one of the analyzed excavations is located on the waterside, where usually only excavations located on the airside are taken into account. All numerical simulations were performed using the ZSOIL.PC FEM (Finite Element Method) system.