Response of Buildings on Isolated and Raft Foundations Subjected to Tunnelling in Sandy Soil

Abstract This study advances understanding of how tunneling impacts buildings with different foundation systems, providing critical insights for safer underground construction. Through combined experimental and numerical analyses, the ground and building responses of structures resting on isolated and raft foundation systems were investigated. A 1 g scaled laboratory model of a tunnel and building was developed, complemented by a series of 3D finite element simulations assessing the behavior of reinforced cement concrete (RCC) framed buildings in sandy soil. Key parameters, including tunnel cover depth ( C/D ) ratios, tunnel volume losses (Vt), building eccentricity (e), and foundation type, were rigorously analyzed. Numerical results, validated against large-scale experiments and field data, offer high-fidelity predictions of surface settlement, zone of influence, foundation movements, and internal force distributions (shear, axial, and bending moments). Findings reveal that buildings on isolated footings suffer significantly greater surface and footing settlements, as well as higher induced stresses, compared to those supported by raft foundations. The study benchmarks these observations against established literature and standards, enabling the reliable classification of damage to buildings affected by tunneling activities. By offering robust data and predictive models, this research equips tunnel designers, engineers, and risk assessors with critical knowledge to optimize foundation choices, minimize tunneling-induced damage, and enhance urban infrastructure resilience.