An innovative test method for mechanical properties of sandstone under instantaneous unloading confining pressure
Why this work is in the frame
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Bibliographic record
Abstract
With the increase of underground engineering construction depth, the phenomenon of surrounding rock sudden failure caused by supporting structure failure occurs frequently. The conventional unloading confining pressure (CUCP) test cannot simulate the plastic yielding and instantaneous unloading process of supporting structure to rock. Thus, a high stress loading-instantaneous unloading confining pressure (HSL-IUCP) test method was proposed and applied by considering bolt’s fracture under stress. The wall thickness of confining pressure plates and the material of bolts were changed to realize different confining pressure loading stiffness (CPLS) and lateral maximum allowable deformation (LMAD). The superiority of HSL-ICPU method is verified compared with CUCP. The rock failure mechanism caused by sudden failure of supporting structure is obtained. The results show that when CPLS increases from 1.35 to 2.33 GN/m, rock’s peak strength and elastic modulus increase by 25.18% and 23.70%, respectively. The fracture characteristics change from tensile failure to tensile-shear mixed failure. When LMAD decreases from 0.40 to 0.16 mm, rock’s residual strength, peak strain, and residual strain decrease by 91.80%, 16.94%, and 21.92%, respectively, and post-peak drop modulus increases by 140.47%. The test results obtained by this method are closer to rock’s real mechanical response characteristics compared with CUCP.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it