Evaluation of effect of basal geotextile reinforcement under embankment loading on soft marine deposits

This paper presents a case history on the performance of a coastal embankment reinforced by a layer of geotextile at the bottom of the embankment on soft marine deposits. The coastal embankment is the sea wall of the Qinshan nuclear power station on the northern side of Hangzhou bay near Shanghai, China. Monitoring of settlement and excess pore water pressure were carried out during and after embankment construction. The finite element method (FEM) was used to analyse the performance of the geotextile reinforcement and its effect on soil behaviour under the embankment loading, based on the field monitored results. Stability analyses were conducted using two approaches: c-ϕ reduction in FEM, and limit equilibrium analysis. Both field and simulation results indicate that the geotextile has an effect on reducing the vertical displacements of subsoil. However, the results show basal reinforcement cannot increase the overall factor of safety, but the factor of safety at the local position, under reinforcement, can be increased during the construction procedure, and this is due to the confinement of the soil element by the reinforcing fabric. Thus, in these circumstances, one layer of basal geotextile reinforcement can prevent sudden failure of subsoil during embankment construction.