This dataset supports the study of stress-dependent seismic velocity behavior in fractured rocks using acoustoelastic and effective medium theories. It includes experimental data, MATLAB code, and simulation results for computing Thomsen-type anisotropic parameters and phase velocities under varying crack densities and prestress conditions. The study combines theoretical modeling with experimental verification to characterize acoustoelastic signatures in fluid-saturated fractured media. All code files included in this submission are original and developed by the authors. Mentions of “Winkler” and “Liu” refer to referenced models or publications and do not indicate code reuse. Therefore, the code is fully compatible with the CC0 license and is released under that waiver.

Description of the Data and File Structure

This dataset contains both experimental and numerical components related to acoustoelastic wave propagation in fractured rocks. All files are organized by function:

Experimental Data

• 0_HD-2-1-20230829-193251-Strength-data.xlsx:
  Contains raw and processed experimental measurements of wave velocities, strength parameters, and stress conditions on fractured rock specimens.
  • Columns include: axial stress (MPa), confining pressure (MPa), P-wave and S-wave velocities (km/s), and derived elastic parameters.
  • Units are provided in the first row. Missing data are indicated with NaN.

MATLAB Code

• Thomsen_parameters:
  Computes Thomsen-style anisotropic parameters (ε, γ, δ) based on nonlinear acoustoelastic theory.
• Effective_moduli.m:
  Implements a crack-density-dependent effective medium model to estimate bulk and shear moduli under varying prestress.
• experimetal_data_verification.m:
  Compares theoretical predictions with laboratory data, computes fitting errors and plots verification figures.
• Phase_velocities.m:
  Simulates phase velocity dispersion curves in fractured rocks using the Acoustoelastic-Hudson-Crack Model (AHCM).

Results

• results.zip:
  Contains figure data used in the main manuscript.

  Subfolders include:

  • /wavefield_outputs/: Contains simulated wavefield snapshots and seismic gathers in .dat format. These outputs are generated under varying crack densities and confining pressures, and represent the key modeling results used for figure generation and quantitative analysis. Each snap_xxxxx_component.dat file represents a wavefield snapshot at time step xxxxx for a specific stress or velocity component (e.g., txx, tzz, vx). These snapshots have spatial dimensions of 807 × 807 grid points and are saved in single-precision binary format (real*4). Corresponding .dat waveform records such as seistxx.dat capture the temporal evolution of the same physical component at a specific receiver location. seisXXX.dat files record the temporal evolution of specific stress or particle velocity components (e.g., seistxx.dat for txx, seisvx.dat for vx, seistzz.dat for tzz, etc.) at one or more receiver locations. These files are stored in single-precision binary format (real*4) and contain 1D seismic traces sampled over time. Each file corresponds to the same physical quantity as represented in snap_xxxxx_XXX.dat snapshot files, which provide the spatial distribution of the wavefield component at selected time steps. Together, the seisXXX.dat and snap_xxxxx_XXX.dat files enable joint time-space analysis of wave propagation behavior under different loading and material conditions.

  • other scripts:

    snapshot.m
    This script reads and visualizes a 2D wavefield snapshot from binary data. 

    Purpose: Visual inspection of the spatial distribution of stress or velocity components in the wavefield, useful for analyzing wave propagation characteristics.

    ht.m
    This script loads a seismic trace seistxx.dat (representing the stress component txx over time) and the source wavelet wlet.dat, and compares them in both time and frequency domains. 

    Purpose: Estimate propagation velocity from arrival time differences and evaluate the waveform response in the σxx component.

    htht.m
    This script functions similarly to ht.m, but focuses on the velocity component seisvx.dat (e.g., particle velocity in the x-direction). 

    Purpose: Analyze wave propagation and waveform features using the particle velocity component, enhancing the understanding of dynamic responses.

    open.m
    This is a multi-purpose script with several capabilities: Seismic trace visualization (seistzz.dat); Wavefield snapshots; Source wavelet analysis; Source dimension and directional energy analysis.

Supplementary Finite-Difference Model

RSG-FD: Finite-Difference Modeling of Wave Propagation in Anisotropic Media

Description:

This dataset contains the input files, source code, and output needed to run 2D finite-difference wavefield simulations in anisotropic elastic media. The simulations are part of the RSG-FD (Rotated Staggered Grid Finite Difference) modeling framework for seismic wave propagation.

Folder Structure and File Descriptions:

Usage Instructions:

1. Ensure that all .dat and .wok files are in the same directory as a.out.

2. To run the simulation, execute the binary:

   ./a.out

3. The output wavefield snapshots and synthetic seismograms will be stored in generated subfolders or output files (not included here but typically saved during runtime).

Sharing/Access Information

This dataset is exclusively available via Dryad. All code files included in this submission are original and developed by the authors. Mentions of “Winkler” and “Liu” refer to referenced models or publications and do not indicate code reuse (Winkler, K. W., & Liu, X. (1996). Measurements of third‐order elastic constants in rocks. The Journal of the Acoustical Society of America, 100(3), 1392-1398.).

There are no access restrictions. All files are under open license for research and educational reuse.

Code/Software

All modeling scripts were written in MATLAB R2022a. Required toolboxes include:

• Signal Processing Toolbox
• Curve Fitting Toolbox
• Optimization Toolbox (optional)

To reproduce figures and results:

1. Load experimental data using experimetal_data_verification.m
2. Run Effective_moduli to compute nonlinear effective parameters
3. Use Thomsen_parameters to analyze anisotropy parameters
4. Use Phase_velocities to simulate directional velocities

For large-scale wavefield simulation, unzip RSG-FD.zip and follow the instructions in the included README_RSG.txt file.