Effect of Underground Structures in Earthquake Resistant Design of Surface Structures

This research deals with the question of whether, and under what circumstances, the presence of underground structures should be taken into account for the earthquake resistant design of neighbouring surface structures. In order to investigate the effect of underground structures on surface seismic motion, a series of dynamic plane-strain numerical analyses were conducted, considering a circular tunnel embedded in a viscoelastic half-space, and a harmonic SV-wave excitation. The numerical methodology, based on the Finite Difference Method, aims at quantifying the effect of the soil medium characteristics, excitation frequency, tunnel diameter, depth of construction, and relative flexibility of the lining compared to that of the surrounding soil. Conclusions contain preliminary criteria identifying the cases when the presence of an underground structure should be considered in the design of a surface structure.