FEM Modelling of the Seismic Behavior of a Tunnel-soil-Aboveground Building System: A Case History in Catania (Italy)

The Role of Shear Wave Velocity and Non-Linearity of Soil in the Seismic Response of a Coupled Tunnel-Soil-Above Ground Building System

“…The aim of the present work was to study the effects of soil V S profile and non-linearity on the full-coupled tunnel-soil-aboveground building system investigated in [20]. The dynamic parameters of the soil and the seismic inputs at the bedrock were appropriately modified according to the classification of [24], then different FEM models and therefore numerous parametric analyses were developed.…”

“…The benchmark of the FEM analyses was a cross-section of the Catania (Italy) underground system actually under construction. The section includes an aboveground building (Figures 1,2) [20]. The geotechnical characterization of the soil, performed in two different phases (July 1999and December 2005-January 2006, shows the soil profile reported in Figure 1 and is characterized by a silty clay (ALg) and a clay (Aa) sub-lithotypes, which belong to the same lithotype, whose Young's modulus Es0 is constant for the first 10 m at a very small-strain and then increases linearly with depth (in the 300-1700 MPa range) and whose unit weight () is equal to 20 kN/m 3 .…”

“…Due to probable resonance (as it will be shown in the following Section 4.2.1, the A80 and B75 cases had a strong amplification from the bedrock to the foundation level especially for the E18 and E26 inputs; the A36 case showed lower Ra due to the greater values of D; the B30 case showed lower Ra values in comparison to previous cases, far from possible resonance conditions. For the same In order to analyze deeply the influence of the tunnel and the aboveground structure on the seismic response, three other configurations were analyzed in previous studies [20]: one represents the free-field conditions; the second one includes only the tunnel; the last one includes only the aboveground structure. These analyses were also performed by means of an equivalent linear visco-elastic model, characterized by degraded G and D, depending on the expected peak horizontal acceleration at the ground surface according to suggestions given by [26].…”

“…During an earthquake, the vibrations of aboveground structures may modify the dynamic response of tunnels [7,8]; at the same time, the presence of shallow tunnels may alter the response of aboveground structures. Most of the published papers consider only tunnel-soil systems [9][10][11][12][13][14][15], while a few consider tunnel-soil-aboveground structure systems (TSS systems) [16][17][18][19][20].…”

“…The present paper deals with parametric analyses performed by means of FEM modeling and involving a TSS system, with differing VS profiles and D, in order to underline the role of estimating these parameters. Using the case history of the underground network in Catania (Italy) and taking a cross-section including an aboveground building [20], the real VS profile [21] was modified according to the four soil types reported by the Italian Technical Code [24].…”