Static and Dynamic Mechanical Properties of Crystalline Rocks from the Canadian Shield
Bibliographic record
Abstract
Crystalline rocks, comprising the majority of the Earth’s crust, play a critical role in the global energy transition by serving as reservoirs for essential minerals, geothermal energy, and as storage sites for heat-emitting radioactive waste. Despite their significance, research on the elastic properties of crystalline rocks remains limited, hindering advancements in seismic exploration for these environments. A key challenge is the dispersion of mechanical properties across different frequency scales, which creates discrepancies between ultrasonic laboratory measurements and field seismic data, particularly in fluid-saturated porous rocks. Understanding these properties is essential for bridging this gap and improving subsurface characterization. This thesis builds on the need to address the knowledge gap in the seismic properties of crystalline rocks by investigating the static and dynamic mechanical properties of granite and foliated gneiss from the Canadian Shield. For granite, experiments were conducted on both intact and thermally cracked samples under different fluid saturation conditions (dry, water, and glycerine). Key mechanical properties, including Young’s modulus, bulk modulus, and Poisson’s ratio, were measured across a range of differential pressures (5–25 MPa) and frequencies (0.02 Hz to 1 MHz). The results revealed significant stiffening upon fluid saturation, notable dispersion, and an attenuation peak within the borehole logging frequency range. The low frequency limit of Biot-Gassmann fluid substitution theory provided a general framework for interpreting some of the experimental results, its applicability in porous crystalline rocks would require careful consideration. For the foliated gneiss, measurements of unconfined compressive strength, indirect tensile strength, and ultrasonic wave speed revealed a strong dependence of mechanical properties on foliation orientations. The results demonstrated that both micro- and meso-scale anisotropy significantly influence the elastic behavior and failure patterns of the rock. Velocity anisotropy reached 25%, and unconfined compressive strength (UCS) anisotropy was approximately 30%, highlighting the role of anisotropy in controlling the mechanical response of foliated rock. These findings contribute to a deeper understanding of the complex mechanical behavior of crystalline rocks, providing insights critical for their application in energy exploration, geothermal systems,and underground waste storage.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".