Earthquake-induced permanent deformations in the landfalls of submerged-floating tunnels in sand

A methodology for the evaluation of earthquake-induced permanent deformations in the landfalls of submerged-floating tunnels in sand is proposed. The methodology involves the computation of slope displacements due to temporary exceedance of the soil strength, and the estimate of the deformations associated with pore pressure build up and post-earthquake pore pressure dissipation. Local seismic response analyses and adequate soil structure interaction models are required to assess the stress distribution in the soil mass and in the structural components, respectively. The methodology was applied for the feasibility study of three submerged-floating tunnels in the Messina Straits, Italy, and the results of this study are presented with emphasis on the geotechnical aspects. The seismic behavior of the Messina Straits sand was investigated in the laboratory. Cyclic triaxial tests were carried out on samples reconstituted to match the field relative densities and shear wave velocities.