Analysis of Pile Foundation of an Underground Building Under the Influence of Tunnel Using Plaxis 3d

Abstract

Day by day competition is increasing for surface space, to fulfil the objective of sustainable development, use of subsurface space becomes very important. Underground structures being difficult and uneconomical to construct were restricted to only special structures like tunnels, hydropower stations, railway platforms, defence purpose buildings and mining. But presently, in a increasing number of cases, public buildings are also being built underground in some of the metro cities for many reasons, most common reason being effective use of land and location. Construction of underground multi-storey building is provided with pile foundation. But in future, this pile foundation, being at large depths, may get affected by newly built tunnel passing close to it. This project mainly deals with analysis of pile foundation of building under the influence of tunnel with the use of finite element analysis software PLAXIS 3D. For analysis purpose, a fully developed model was made and simulated for various positions and diameters of tunnel with respect to foundation of building. Results were analysed to find changes in the behaviour pile foundation in terms of total displacement. After thorough analysis of results of simulation, it was found that pile foundation of building is influenced by tunnel only when tunnel is in very close vicinity of pile and its influence is negligible if located far away from the structure. The distribution of internal forces induced by tunnel depend on the position of the pile with respect to the tunnel horizontal axis. The critical position of tunnel corresponds to pile with a tip just below of the tunnel. When tunnel is located at various depths, the variation of total displacement with depth of pile depends upon position of tunnel and the tip of pile. The diameter of tunnel also has small influence on displacement of pile. Displacement of pile is also influenced by diameter of tunnel to a small extent.