Tunnel Analysis of Dhaka Subway using PLAXIS 2D Considering Building Loads of Pile Foundation

Abstract

To ease the increasing traffic in the city, an underground Dhaka metro system is being planned. Ground movement and surface settlement must get special consideration during the planning of the subway due to the city's high level of congestion. For the long-term design of the tunnel, it is also necessary to take into account the increase in building density as the city expands. Utilizing Plaxis 2D, a 2D finite element analysis was performed for this project. Different soil profiles representing various parts of the Central Dhaka city were taken into consideration, and the surface settlement brought on by tunnel excavation was looked at. It was discovered that as tunnel excavation depth grows, surface settlement diminishes and the settlement trough widens. Additionally, the axial forces and grouting pressure needed for a particular surface settlement after the tunnel was built were analyzed, and it was shown that both of these requirements rise with tunnel depth. Additionally, an analysis of the tunnel lining stresses under various groundwater conditions was done. It was discovered that the axial forces the tunnel lining experiences increase with tunnel depth. Additionally, the future rise in ground water level will primarily cause an increase in the axial forces, bending moments, and shear forces.