Earthquake Return Period and Its Incorporation into Seismic Actions

Abstract

A revision and adaptation of the seismic design criteria established in the practice for straight tunnels of circular shape is presented. Two methods of analysis are considered: the free-field deformation method and the soil-structureinteraction method. The axial, flexural and ovaling deformations caused by the passage of seismic waves are analyzed, and practical expressions for computing the associated mechanical elements are given. The application of both methods is illustrated by solving the case of a typical tunnel in soft ground, which clearly shows the effect due to the stiffness contrast between the two elements.