AND SEISMIC MONITORING
2D soil response modeling
1D and 2D site response modeling of the Rhone valley (France) and evaluation of seismic hazard
In the framework of the reevaluation of the seismic hazard for a nuclear site, a specific study is conducted to evaluate the site effect related to the thick sedimentary layers and the geometry of the Rhone Valley. In particular, 1D and 2D modeling using finite difference algorithms with constraints from empirical data are used to evaluate site effects.
Determination of a soil model by geophysical measurements and soil response analysis
for a SEVESO site.
Passive geophysical investigations (Ambient Vibration Array and Mutichannel Aquisition of Surface Wave) for the definition of the Vs velocity profiles. Dynamic soil response analysis for the seismic microzonation of the site.
Installation of accelerometric stations
Assistance for the selection and installation of accelerometric stations at several sites in France.
We provided support and assistance to our client to identify the most suitable location and the appropriate instrumentation system for a permanent station dedicated to seismic monitoring and data acquisition for future studies. The selection of the appropriate location was based on site visit, analysis of ambient noise acquired by temporary stations and the analysis of the technical constraints imposed by the Client. We supported the client in the installation, parameterization and commissioning of the instruments. We also analyzed the recorded data for an initial time period in order to provide feedback on the performance of the instruments and on the earthquakes recorded.
Ground motion assessment at great depth
Characterizing site-specific ground motion at great depth for the Cigéo nuclear waste repository project (France)
Client: ANDRA Year: 2021/22
Cigéo is the French project for a deep disposal facility of radioactive waste, located in the Eastern part of the Paris Basin, a highly stable geological environment characterized by very low seismicity. In order to quantify seismic hazard at various return periods and several depths the data collected at the seismic stations on site are processed in order to compute the empirical transfer functions.
The collected data and the soil profile are used to develop site-specific adjustment factors to ergodic GMM.
Such adjustment factors together with the empirical transfer functions and related uncertainties can be used to remove the ergodic assumption on the site term of GMMs in order to improve classical ergodic seismic hazard assessment for structures at surface and at depth.
Geophysical investigations dam site
Geophysical investigations for the determination of the velocity profiles and the EN 1998-1 soil class for dam of the Rhône river
The objective was to acquire and process the geophysical data recorded on the site, in order to determine a set of parameters allowing the determination of the soil class (EN 1998-1) and to carry out the dynamic soil response analysis.
Three passive methods were employed:
Horizontal-to-vertical spectral ratios from noise, Ambient Vibration Array (AVA) and Multichannel Acquisition of Surface Wave (MASW).
Multiple inversions of dispersion curves provided robust shear wave velocity profiles down to two hundred meters