PSI - Issue 62

4

Diana Salciarini et al. / Procedia Structural Integrity 62 (2024) 514–521 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

517

Fig. 4. Section of three-dimensional soil model.

Subsequently an ideal viaduct was included in the model, with its axis aligned along the direction of the landslide movement. The considered viaduct includes piled foundations, with each foundation modelled using 6 piles of 1.0 m in diameter (see Fig. 5). Since the primary focus is on studying the interaction between the soil and the structure at the foundation level, simplifications have been adopted for the elevated structures. These simplifications include modelling the piers as beams with linear elastic behaviour and the deck of the bridge as a beam with a simple static support scheme.

Fig. 5. Panoramic overview of the modeled viaduct and 3D topography.

For the soil volume, the constitutive model employed is the Hardening Soil with Small Strain (HS Small). This model is effective in capturing hysteresis during cyclic loading, generating damping, and the attenuation of the dynamic stiffness of the soil. The degree of hysteretic damping is contingent on the applied load amplitude and the corresponding strain amplitudes. Tab. 1 summarizes the assumed values for the soil properties in the FE model.

Table 1. Values of the soil properties assumed in the 3D model. Parameter Symbol

Clayey soil HS-small

Unit

Constitutive model Soil unit weight

-

-

 sat E ′ 5 re 0 f E ′ o re e f d E ′ u re r f c ′ ′ ′ 

20 20 20

kN/m

3

Mod. sec

MPa MPa MPa

Mod. edom Mod. unl/rel

100

Cohesion

5

kN/m 2

Friction angle Small-strain stiff. G 0ref Shear-strain stiff.  0.7

28

°

100

MPa

0.15e-3

- -

Poisson coeff. Damp. Rayleigh

0.25

3

%

To conduct dynamic analyses for the case study, an earthquake was modelled by applying a prescribed displacement at the base of the model (Fig. 6), specifically in the direction of the landslide movement, to assess the results under the most critical configuration. The seismic input was determined using the REXEL code (Iervolino et al., 2009), relying on international databases, with a moment magnitude of 6.5, an epicentral distance of 23 km, and an expected return period (TR) of 1980 years.