Numerical Analysis on the Performance of Anchored Diaphragm Walls for a Deep Excavation in Hanoi

This paper presents a case study and numerical simulations for three-level deep basements in Hanoi city supported by anchored diaphragm walls. Numerical analyses performed using the finite element tool PLAXIS 2D with hardening soil model (HS) were compared with the wall deflection profiles observed at each excavation stage from instruments installed on site. The results show that lateral wall deflections predicted by FE analyses were in good agreement with the observed measured in situ. The ratio of the measured maximum horizontal wall displacement, δh(max), to excavation depth (He) was 0.15%. The influence of various parameters such as prestress force and horizontal anchors spacing on the responses of deep excavation (e.g., lateral wall deflection and diaphragm wall bending moment) were analysed and discussed. Finally, a back analysis of wall deflection for final excavation phase was carried out to determine reasonable stiffness modulus value for clayey sand.