The demand for tunnels in densely populated urban areas is growing rapidly to address mobility challenges. Mechanized tunneling is widely adopted in urban environments due to its high productivity and the relatively small ground deformations it induces. However, urban tunneling is highly complex because of the typically shallow depths and interactions with aboveground structures. Therefore, accurately predicting ground deformations induced by mechanized tunneling at the design stage is crucial for assessing potential building damage. To investigate these deformations, a series of centrifuge tunnel tests have been conducted at academic institutions such as the Universities of Cambridge and Nottingham to study the behavior of shallow mechanized tunnels in cohesionless soil. These tests serve as excellent benchmarks for numerical model calibration. Once calibrated to replicate centrifuge test results, numerical models can efficiently analyze a wide range of scenarios at a fraction of the time and cost. This paper investigates ground deformations induced by shallow tunneling in cohesionless soil using numerical models calibrated against selected centrifuge tunnel tests, which encompass varying tunnel diameters, depths, and sand relative densities. The numerical modeling results presented in this paper provide extensive insights into tunnel behavior, illustrating how tunnels respond to different relative densities and depths under tunnel volume losses of up to 5%, approaching failure conditions. Additionally, a comprehensive analysis of ground deformations caused by shallow tunnels in sandy soils and their potential impact on buildings is presented.

Mumbai is an elongated island city and spreading towards northern side as the southern side is sea face. Mumbai Metro Line 3 (MML-3) project corridor from Colaba to Seepz, is fully underground metro of a total length 33.5 km twin tunnel. In this project, 17 nos. of TBMs deployed to construct the tunnel. The tunnel is excavated through Basalt underlying filled up material and soil strata (sandy and clayey). A systematic instrument arrays are installed along the tunnel alignment to monitoring at the ground, on the ground and in the tunnel, existing buildings along the tunnel alignment in the influence zone (both side of tunnel alignment) as per monitoring scheme. Monitoring of instruments was done as per the frequency required for tunnelling activities based on the excavation stages and to acquire the recorded data. Based on the monitoring data and their interpretation, design modification has been done to achieve safe tunnelling which is the first and foremost requirement in urban tunnelling. This paper highlights the surface settlement at the ground surface and in the tunnel excavated zone due to tunnelling.