Grenoble Field Experiment - Geophone and DAS with Simulations

This upload contains field data recorded at a site on the Grenoble campus, where a pre-existing buried concrete foundation is present, along with numerical simulations based on the wave equation using the Spectral Element Method (SEM), replicating the site conditions.

Content Overview:

vs, vp, rho_c: Shear wave velocity (vs), compressional wave velocity (vp), and density (rho_c) models used for numerical simulations with the Spectral Element Method (SEM). The mesh consists of 100×100×60 elements, each 1 meter in size, with a free surface at the top and 14 ABS elements included at the edge. The interpolation order is 4. The source is a Ricker wavelet with a central frequency of 125 Hz, expressed by vertical force located at x = 20m, y = 50, z = 0.

d2x_dt2, d2z_dt2, dexx_dt: Synthetic observables from the simulation.

d2x_dt2: Horizontal acceleration in the x-direction

d2z_dt2: Vertical acceleration

dexx_dt: Strain rate calculated using a finite difference approach based on receivers spaced 2 meters apart, matching the experimental setup.These datasets include 30 recordings: 15 located before the foundation and 15 after, each spaced 1 meter apart.

d2x_dt2 (GEO), d2z_dt2 (GEO), dexx_dt (DAS): Field recordings from geophones and DAS. The data have been recorded using 14 Hz geophones and Distributed Acoustic Sensing (DAS) with a 2-meter gauge length and 1-meter channel spacing. Refer to the figure Site_configuration for the layout.

14 total recordings: 7 located before the foundation and 7 after, spaced 2 meters apart starting 13 meters before the foundation.

Signals have been bandpass filtered between 10 Hz and 50 Hz.

 GEO and DAS refer to the instruments used to measure each observable.

Note: The layout of the receivers in the simulation and the field experiment is nearly identical, with a few differences:

Sensor spacing: 1 meter in the simulation, 2 meters in the field experiment.

Number of sensors: 15 before and 15 after the foundation in the simulation; 7 before and 7 after in the field experiment.

Sensor alignment: In the simulation, all observables were recorded at the same spatial locations. In the field, the geophone and DAS lines were parallel but offset by approximately 30 cm.