SCEC2024 Poster #186: Development of a Nonlinear Soil Model in SW4 (Seismic Waves, 4th Order)

Group B, Poster #186, Ground Motions (GM)

Development of a Nonlinear Soil Model in SW4 (Seismic Waves, 4th Order)

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Poster Presentation

2024 SCEC Annual Meeting, Poster #186, SCEC Contribution #13825 VIEW PDF

High performance computing is advancing seismic risk mitigation by enabling simulations of seismic wave propagation to be run on a regional scale. SW4 (Seismic Waves, 4th Order) is one such seismic wave propagation code, which has demonstrated the ability to simulate large magnitude earthquakes in regional models at unprecedented frequency resolutions up to 10 Hz. However, this extended frequency range is where resonance lies for many engineered structures, as well as for many sedimentary sites that such structures are founded on. During large earthquakes, these zones of soft, near-surface sediments can be subject to significant deformation, and the corresponding large stresses can result in... the soft sediments exhibiting nonlinear behavior. SW4 is unable to capture the nonlinear soil response for such events because it is a linear wave propagation code. In this work, we present an implementation in SW4 of the equivalent linear (EQL) method, which is a widely accepted and applied, simplified nonlinear soil model where material properties are updated in iterative linear simulations. The final product is a computationally feasible and physics-based method of accounting for the effects of large strains on material properties in SW4, and the iterative linear scheme is compatible with SW4’s existing linear wave propagation formulation. This will advance SW4’s ability to model high risk earthquake scenarios, particularly for critical infrastructure founded on the soft soil sites that experience the most nonlinear behavior during large earthquakes.
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