Analysis of a Deep Excavation Adjacent to the Metro Tunnel Line of Ho Chi Minh City

The back analysis is carried out to investigate and assess the deep excavation by Plaxis 3D software and actual Nexus project monitoring data that includes Metro Tunnel system line No. 1 (Metro Tunnel) deformation as well as horizontal diaphragm wall displacement (normal diaphragm wall (DW) and buttress walls (BW)). The validity of the 3D Plaxis finite element, as well as a preliminary assessment of the acceptability of E50ref according to undrained shear resistance (Su) in the case of cohesion soil and E50ref according to SPT value in the case of cohesionless soil, combined with subdividing a thick sand layer into many elemental layers. In addition, the stiffness of the Metro tunnel in the cross-sectional and longitudinal directions is different, making the two—directional behaviour of the tunnel anisotropically. It has recommended a reasonable stiffness ratio (E1/E2) for these two modules based on the back analysis value, which is pretty comparable to Metro tunnel system monitoring data. In this study. Moreover, the buttress walls effectively reduce the deformation compared to the normal diaphragm wall.