By the year 2035 it is estimated that Delhi and Mumbai will become two of the most populous cities around the globe. The massive population growth rate has led to the rise of land scarcity, urbanization, and industrialization and developments for rapid transit systems have made accordingly. Modern rapid transit systems comprise Metro rails and subways etc., and increase underground-construction activities. Nowadays, the tunnel-construction process heavily relies on massive machineries such as tunnelling-boring machines (TBM) and operations that produce great hindrance in the soil mass resulting in ground settlement at the surface. This study aimed to address these issues through small-scale laboratory experiments and further amplification to real-valued problems utilizing numerical methods. A cubic box of edge length 1 m made up of mild steel was generated to simulate a tunnelling operation and aluminum-made lining were used to simulate concrete tunnel linings. A finite element-based numerical investigation was done for a 2D elastoplastic numerical tunnel model with dimensions of 42 m × 42 m. Analysis was carried out on Optum G2 software. The analyzed variations in lining shapes of lining included circular, horseshoe, arch, elliptical, and square. Results showed that elliptical-shaped linings experienced the least ground settlement and these are recommended for places where surface settlement may cause major damage. It is also recommended that square-shaped linings should not be used in such situations due their higher settlement values.

Concrete gravity dam is considered as acritically important mega structure and lifeline of countries with rich water resources. Its failure due to natural and manmade hazard may cause a huge loss of human life and economy. The recent terror attacks involving intentionally crash of aircrafts have raised the safety concern of these critical structures. In the present study, a finite element analysis has been carried out to analyse the behaviour of concrete gravity dams against possible aircraft crash. Reaction-time curve of fighter jet Phantom F4 has been applied on the crest of the dam from upstream face. The Concrete Damaged Plasticity model has been incorporated to predict the behaviour of concrete under high strain loading. It has been found that at a crash speed of Mach 1, fighter jet had caused severe damage to dam. Although the penetration will be small on the loading face of the dam due to massiveness of structure, however, the concrete around crest and neck will fail in tension. Further, redistribution of moments will cause failure of the structure. Maximum deformation has been found to be 8.8 mm. Stresses are quite high at the impact face, however it diminishes at a depth of 8 m from the impact face.

The safety of critical infrastructures like concrete gravity dams against high-strain dynamic loads has gained significant attention due to their strategic importance. This study presents a finite element analysis to evaluate the structural response of five differently shaped concrete gravity dam models under aircraft impact loading. A three-dimensional simulation was performed using the Finite Element Method (FEM), employing the Concrete Damaged Plasticity (CDP) model to accurately capture the nonlinear behavior of concrete under high-strain rates. The impact of a Phantom F4 aircraft impacting at a velocity of 215 m/s, simulated using Riera’s reaction-time force history, targeting the freeboard region of each dam model. Comparative analysis revealed that the maximum deformation (620 mm) and tensile damage were concentrated around the impact zone, particularly for Dam 1, while other dam geometries exhibited distributed stress patterns and lesser damage. Stress-time history plots demonstrated tensile dominance near the impact region and compressive dominance near the dam base. The findings indicate that dam geometry significantly influences the damage and stress distribution under aircraft impact, with certain profiles being more vulnerable. This research provides critical insights for the design and assessment of concrete gravity dams to enhance their resilience against potential high-energy impact scenarios.