Assessing seismic vulnerability in metro systems through numerical modeling: enhancing the sustainability and resilience of urban underground utilities (3U)

The significance of meticulous consideration for the complex domain of Urban Underground Utilities (3U), particularly the subterranean utilities in seismic-vulnerable metropolises, demands an exclusive focus on the formulation of designs that embody sustainability and resilience. In the present study, specific aspects of seismic vulnerability are focused on the structural integrity of the tunnels, the impact of ground motion effects, site characterization, the performance of construction materials under seismic conditions and the influence of overburden pressure on tunnel stability to enhance seismic resilience. The seismic vulnerabilities of the tunnel in Delhi metro were meticulously analyzed using a triad of analytical frameworks: geostatic, eigenvalue, and nonlinear time history analyses. MIDAS GTS NX, a cutting-edge finite element software, was employed to assess the tunnel’s sensitivity to variations in material properties, tunnel lining characteristics, and overburden depth. The analysis revealed that material properties significantly influence structural forces, surpassing the impact of the seismic event’s magnitude. Interestingly, increasing the tunnel lining showed minimal changes in ground and tunnel crown displacement. However, higher overburden depth and Peak Ground Acceleration (PGA) led to increased axial force and bending moment values. These findings provide valuable insights for stakeholders like consultants, designers, and policymakers involved in hazard mitigation efforts.