Behavior of Bridge Abutment Foundation in Mixed Ground Condition

Bridges are prime components of transportation network. Subsoil conditions, water table depth, and seismicity have crucial impact on the foundation part of a bridge abutment which may mainly consist of pile or open foundation. Hence, it is necessary to study the effect of soil–structure interaction of bridge foundation under seismic force. To study the nonlinear behavior of bridge abutment and its foundation, different sets of soil models with various seismic forces have been developed by using FEM-based software for a typical bridge abutment foundation. To gain an insight into the seismic response of abutment foundation, its geometrical profile has been further modeled for both pile and open foundations. Different surrounding subsoil conditions (soft soil, weathered rock, etc.) provide variation in safe bearing capacity, ground settlement, stability factor, etc. The results of the present study show that the factor of safety of the bridge abutment gradually increases by 4–12% and ground settlement decreases by 6–16% when ground condition changes from medium to stiff clay followed by weathered rock. Ground settlement increases by 30–135% when seismic zone changes from Zone-III to Zone-IV with higher PGA, even for same soil condition.