Tunnel-soil-bridge seismic interaction on soft clay
Abstract
Seismic tunnel-soil-bridge interaction in high plasticity soft clays can lead to significant ground motion vari-ability, affecting on-ground structures located next to or above underground facilities. This technical note pre-sents a numerical study aiming at establishing tunnel-bridge seismic interaction effects on soft clays. Initially, we revised this interaction considering the impact that frequency content, intensity, and strong ground motion duration have on the interplay between incoming seismic waves reflected in the tunnel and the energy feeding back from the bridge swinging back and forth during a large earthquake. Series of three-dimensional finite difference models were developed. Seismic analyses considered both normal and subduction events with a return period of 250 years. From the results gathered in these analyses, the ground motion modification in the sur-rounding soil occurs in both the transverse and longitudinal components due to tunnel-bridge interaction. The tunnel underneath the bridge establishes detrimental soil-structure interaction effects for normal and subduction events.
