Study of Surface Displacements on Tunnelling under Buildings Using 3DEC Numerical Modelling

Area of Science:

• Geotechnical Engineering
• Urban Infrastructure Development
• Soil Mechanics

Background:

• Shallow underground structures like metro lines are common in urban areas, often beneath existing buildings.
• Tunneling operations induce significant ground movement and distortion in surrounding soil strata.
• The impact of tunneling on granular soils and overlying structures requires further investigation.

Purpose of the Study:

• To investigate surface displacements in granular soils due to tunneling.
• To analyze the influence of building characteristics (storeys, eccentricity) on tunnel-soil-structure interaction.
• To evaluate the effect of geosynthetic layers on footing behavior.

Main Methods:

• Parametric numerical studies using 3DEC software to simulate tunneling effects.
• Model validation against field data from a tunnel in South India.
• Analysis of surface and subsurface displacements under various conditions.

Main Results:

• Building inclusion reduces surface displacements in dense granular soils.
• In very dense strata, buildings can increase surface displacements compared to no-building scenarios.
• Increased building eccentricity leads to surface settlements approaching those without a building.

Conclusions:

• Building characteristics and soil density significantly influence tunnel-induced ground movements.
• Geosynthetic layers may mitigate settlement effects, warranting further study.
• 3DEC software is applicable for simulating such complex urban tunneling scenarios.