STRUCTURE, GEOLOGY, AND ENGINEERING PROPERTIES OF TWO CARBONATIC FINE-GRAINED SOILS
Notice bibliographique
Résumé
Soft, carbonate-rich, fine-grained soils are commonly found in the glaciated regions of the northern United States and throughout Canada. In addition to the high compressibility potential and low shear strength, these sediments are typically characterized by alternating layers of silts and clays as well as high calcium carbonate content. The unique properties of these deposits make them challenging soils for geotechnical engineers. Despite the prevalence of soft carbonatic soils in Indiana and the concerns associated with their behavior, very limited work has been done to study their engineering properties. This was the motivation for the research, which is founded on an in-depth characterization of a glaciolacustrine carbonatic fine-grained soil deposit formed about 22,000 calendar years ago in the southwestern part of the State of Indiana, USA. The aim of the investigation was the developing of improved knowledge of the behavior of carbonatic fine-grained soils. The project involved field tests (seismic cone penetration tests, standard penetration tests, field vane shear tests), and laboratory experiments (index tests, incremental and constant rate of strain consolidation tests, and K 0-consolidated undrained triaxial tests) conducted on high quality Shelby tube samples. Additionally, the mineralogy and microstructure of the soil was studied in detail. The laboratory tests revealed that the deposit was not homogeneous, as was initially anticipated, but was, instead, formed by two types of soils that repeated in horizontal thin layers. These two soils, referred to as ‘soil M’ and ‘soil C’, both had very high calcium carbonate content, but show distinct index and engineering properties that were ascribed to differences in mineralogy and composition. This stratification was not detected by the field tests. A detailed study of the local geology combined with the observations of the differences between the morphology of pyrite and the clay mineral composition between the two soils, as well as the presence of biological intrusions in only one of the two soils, suggest that different source materials and sedimentary environments alternated during the formation process of the deposit. The microstructural investigation showed that the soil consisted of clay platelets that were covered by a thin layer of a carbonatic coating and interconnected by carbonatic bridges to form aggregates. The laboratory results showed that these interparticle bonds altered the macroscopic behavior of the soil (i.e. index and engineering properties). The consolidation tests showed that the deposit had an overconsolidation ratio (OCR) less than 2 and compressibility parameters markedly dependent on stress. K0-consolidated undrained compression triaxial tests showed that both soils exhibited normalized behavior and that the relationship between strength and stress history was well described by the SHANSEP equation (although the SHANSEP parameters differed for the two soils). Comparison of the field data and laboratory results provided the means to validate published correlations for interpretation of the geotechnical properties of carbonatic soils from field results. For the site examined, correlations to estimate shear wave velocity, stress history, and undrained strength from cone penetration tests (CPT) results were identified.
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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 | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 ».