Shoreline Geomechanics at Hopewell Rocks Provincial Park, New Brunswick, Canada: Stability of the Elephant Rock, Sentinel, and Lover’s Arch Formations
Notice bibliographique
Résumé
Sea stacks are natural pillars of rock that have been detached by wave action and other erosional processes from adjacent cliff-lined shores. The Hopewell Rocks Provincial Park in New Brunswick, Canada is situated along the coast of the Bay of Fundy, which is home to the largest tidal range in the world. The Park is a popular attraction for geotourism, as it hosts numerous sea stacks and arches that can be accessed on foot during low tide and by kayak during high tide. Approximately 2-3 small scale rockfalls from the cliffs occur at the Park each year, and larger scale rockfalls from the sea stacks occur much less frequently. This research investigates the failure mechanism through a back analysis of the partial collapse of the Elephant Rock formation and the stability of the Sentinel, and Lovers’ Arch formations through a forecast stability analysis using geomechanics numerical models. The primary sea stack failure modes in the Park—block failure, sea stack collapse, and sea arch collapse—are evaluated for the Elephant Rock, Sentinel, and Lover's Arch formations, respectively. The partial failure of the Elephant Rock occurred on March 14th, 2016. The geomechanical interpretation of the failure mechansism is supported by: analyses of a 3D Structure-from-Motion (SfM) photogrammetry model of the failure surface; photographs taken before and after the failure; historic tidal, climate, and weather data; and the historic rockfall database from the Park. The failure mechanism of the Elephant Rock is interpreted to be a multi-stage combination of toppling and sliding failures. The failure was driven by progressive tidal erosion that increased stresses at the base, and freeze-thaw cycles that gradually opened fractures at the base when salt water (marine) and at the top when fresh water (precipitation) reached their respective freezing points. The forecast stability analyses of the Sentinel sea stack and Lovers’ Arch sea arch formations were completed using 3D finite element method geomechanics numerical models to assess the potential time to failure of the formations. Geometrical input was provided by unmanned aerial vehicle (UAV)-based 3D SfM photogrammetry models. Four scenarios were analyzed including the present (2021) geometry of the formations, as well as three simulated reductions in the widths of the pillar within the tidal erosion zone. The rates of erosion were determined to be approximately 3 to 6 mm per year by comparison of historic 20th century photographs and current (2021) photographs. The results from the numerical models in this study indicate that failure may occur in approximately 415 to 500 years after 2021 for the Sentinel formation, and 250 to 300 years after 2021 for the Lover’s Arch formation. The results of this study are the first geomechanical interpretations of a past partial collapse and predictive stability analyses of sea stacks and arches at Hopewell Rocks Provincial Park. The analysis framework presented in this thesis can be applied to other coastal stack and arch formations and used to evaluate the risk of collapse to impact public safety and affect geotourism.
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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 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,002 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,005 | 0,001 |
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 ».