Interaction of Underground Tunnel and Existing Shallow Foundations Affected by Normal Faults

In major earthquakes, permanent ground deformations due to the fault movementscause serious damage to the foundations and structures. Although many ofstructural seismic design codes have recommended avoiding the construction ofstructures in the adjacent to active faults, it is not always a viable option. Forexample, the lifeline facilities such as gas tunnels, water supply tunnels andtransportation tunnels, due to their extensive length, cannot often avoid crossingactive faults. Therefore, it is necessary to evaluate the interaction mechanismbetween structures and fault rupture for effective design to reduce the hazardsassociated with surface faulting. This study investigates the interactions ofunderground tunnel and existing shallow foundation affected by normal faultusing the finite element method. The results show that the existence of a tunnelchanges the fault rupture path and in some cases can increase the foundationrotation. It causes the occurrence of severe level of damage to the structure andincreases fear about its instability.