Theme Paper: Earthquake Engineering for Tunnels and Underground Structures. A Case History

Tunnel and large cut-and-cover structure response to earthquakes is dominated by the surrounding ground, and, contrary to shallow-founded structures, does not depend on the inertial properties of the structures themselves. The focus of the underground design is on the free-field deformation of the ground and its interaction with the structure, i.e., a soil-structure interaction phenomenon. This paper summarizes the performance in recent past seismic events of deep, large underground structures, and then elaborates on their design approach: geotechnical, seismic criteria and structural factors. Analytical models are examined and conclusions drawn about their advantages and limitations. A general approach to the design of deep underground structures is illustrated through the on-going design of a particular project.