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.