Simplified vibratory characterization of alluvial basins

TL;DR

This paper presents a simplified modal approach using the Rayleigh method to efficiently estimate the fundamental frequency of alluvial basins, aiding seismic wave amplification analysis.

Contribution

It introduces a simplified, fast modal method for vibratory characterization of alluvial basins, validated against experimental data.

Findings

The Rayleigh-based method provides accurate fundamental frequency estimates.

The approach offers a quick alternative to complex numerical models.

Experimental results agree well with numerical predictions.

Abstract

For the analysis of seismic wave amplification, modal methods are interesting tools to study the modal properties of geological structures. Modal approaches mainly lead to information on such parameters as fundamental frequencies and eigenmodes of alluvial basins. For a specific alluvial deposit in Nice (France), a simplified modal approach involving the Rayleigh method is considered. This approach assumes a set of admissible shape functions for the eigenmodes and allows a fast estimation of the fundamental frequency of the basin. The agreement between modal numerical results and experimental ones is satisfactory. The simplified modal method then appears as an efficient mean for the global vibratory characterization of geological structures towards resonance.