Numerical Investigation of the Influence of Bedding Plane Thickness and Friction on Cracking Pattern and Mechanical Behavior of Shale Under Unconfined Loading Condition Using the Finite-Discrete Element Method (FDEM)
Notice bibliographique
Résumé
ABSTRACT: The finely bedded structure of shale makes its mechanical behavior highly anisotropic both in terms of deformation and strength. The variations in the bedding plane thickness originates from different sedimentation processes occurred during the formation of the shale. It is well known that these features act as weakness planes in the rock matrix and thus studying the mechanical behavior of shale should incorporate the influence of bedding planes. Numerous investigations have been conducted so far to understand the influence of bedding plane orientation on the deformation and strength of shale. However, there exist only a few investigations which studied the influence that bedding plane thickness and friction might have on the mechanical response and cracking pattern of the rock. The present study discusses the results of a series of unconfined compressive test simulations conducted on shale samples with different bedding plane thickness and friction values using the combined Finite-Discrete Element Method (FDEM). The bedding planes have been discretely modeled as a distribution of preferentially oriented defects inside the rock matrix. Experimental results from the shaly facies of the Opalinus Clay at the Mont Terri Underground Research Laboratory (URL) have been used as input parameters to calibrate the numerical model. Simulation results show a difference in cracking pattern and strength of the rock owing to different bedding plane thicknesses but almost no effect due to different bedding plane frictions. 1. INTRODUCTION Shale formations play an integral role in many civil, petroleum, and environmental engineering projects. Shales not only act as an unconventional reservoir for extracting hydrocarbon resources, but also as a potential host rock for underground geological storage of nuclear wastes and as caprock for Carbon Capture and Sequestration (CCS) operations. Shale is formed through the sedimentation and subsequent hardening of fine sediments and thus it features a finely laminated and bedded structure. Platy particles tend to deposit in distinct orientations during the sedimentation of the shale causing an anisotropic texture at the macroscopic scale (Wenk et al., 2008). The layered structure of the shale makes its deformation and strength characteristics highly anisotropic at different scales, for example, at a larger scale it is attributed to the presence of bedding planes (Saroglou and Tsiambaos, 2008). The temporal variations in the sediment supply and flow velocity causes the thickness and properties of the bedding planes to differ along the deposition axis (O’Brien, 1996). These bedding planes act as weakness planes inside the rock matrix and thus understanding the shale mechanical behavior should incorporate the influence of bedding planes (Woo et al., 2021). In addition, the existence of physical discontinuities in the rock such as natural fractures or tectonic features contributes to the anisotropy at the rock mass scale.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».