Behavioural modelling of Toronto Glacial Soils and implementation in numerical modelling

Masoud Manzari, Andrew Drevininkas, Dmitry Olshansky, Abdullah Galaa

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Soil Mechanics

ABSTRACT: l modelling of Toronto Glacial Soils and implementation in numerical modelling Masoud Manzari Thurber Engineering Ltd, Oakville, Ontario, Canada Andrew Drevininkas, Dmitry Olshansky Toronto Transit Commission, Toronto, Ontario, Canada Abdullah Galaa Soil Mechanics and Geotechnical Engineering Institute, HBRC, Giza, Egypt ABSTRACT Constitutive model is the essential part of any numerical analysis. Soil models and associated parameters must signify the characteristics of the soil behaviour that are pertinent to the subject of the analysis. Practical constitutive models should not be overly complex, while must be accurate enough for the purposes of the design. Nevertheless, behaviour of glacial soils in southern Ontario is not fully understood to a level for use in numerical analyses. Further studies are necessary to obtain advance soil parameters for realistic behavioural modeling of the deposits. 126 triaxial test conducted by Toronto Transit Commission on overconsolidated glacial soils were analyzed. This paper provides a summary of the test results and discusses the selected constitutive soil model with associated parameters for glacial soils. The process for calibration of the test results to the model is described and statistical analysis of the obtained model parameters for each soil type are provided. RÉSUMÉ Le modèle du sol est essentiel pour toute analyse numérique. Les paramètres du model doivent refléter le comportement du sol pour le problème à analyser. Un modèle pratique ne devrait pas être trop complexe et doit être suffisamment précis pour le problème à résoudre. Cependant, le comportement des sols glaciaires au sud de l'Ontario n'est pas entièrement compris pour les analyses numériques et d'autres études sont nécessaires pour obtenir les paramètres du sol pour le modèle réaliste de comportement des dépôts. Cent-vingt-six résultats d'essais triaxiaux réalisés par la Commission de Transport de Toronto sur les sols glaciaires sur-consolidés ont été analysés. Cet article présente un résumé des résultats d'essais et décrit le modèle durcissement du sol avec des paramètres associés de till. Les processus suivis pour les essais d'étalonnage du modèle du sol sont décrits et l'analyse statistique du paramètre du modèle obtenu pour chaque type de sol est donnée. 1 INTRODUCTION Numerical modelling is gaining more popularity in analysis and design of deep excavations in Toronto. The main drive toward the use of these more enhanced methods of analysis is to provide confidence and ultimately achieve economic and safe design. However, behaviour of glacial soils in southern Ontario is not fully understood to a level for use in numerical analyses as conservative parameters are commonly provided or simplistic numerical models used. Linear elastic-perfectly plastic soil models, although very simple, have limited use if achieving more realistic predictions are desired. On the other hand, elasto-plastic soil models with yielding and kinematic hardening are more accurate while complex. A practical constitutive model for any analyses should not be overly complex and on the other hand must be accurate enough for the purposes of the analyses. Making a reasonable decision on this issue requires both experience and adequate field/laboratory data. Considering the lack of proper categorized information, it is necessary to carry out further studies in order to provide relatively more realistic behavioural models for the glacial soils and supply appropriate geotechnical properties for the analyses. This generally requires extensive calibration of the enhanced field and laboratory tests to obtain sensible parameters. This paper provides a summary of 126 triaxial test results for the various overconsolidated glacial soils, including cohesive and cohesionless glacial tills and plastic glaciolacustrine clays. Furthermore, the paper describes processes followed for calibration of the test results to the hardening soil model and statistical analysis of the obtained model parameter for each soil type. 2 GLACIAL SOILS OF TORONTO The geological history of the Toronto area has included several advances and retreats of glaciers of Illinoian and Wisconsinan ages (Karrow and White, 1998). The stratigraphy across Toronto varies with cohesive and cohesionless glacial tills, and interglacial deposits of fine grain glaciolacustrine and coarse grain interstadial outwash. The fine grain glaciolacustrine characterized in this study were generally deposited during the Early to Middle Wisconsinan period, typically represented by the Scarborough and Thorncliffe Formations. The glacial tills in this study were generally deposited during the Early to Late Wisconsinan period, represented by the Sunnybrook, Seminary, Meadowcliffe, Newmarket, and Halton Tills

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Masoud Manzari; Andrew Drevininkas; Dmitry Olshansky; Abdullah Galaa (2014) Behavioural modelling of Toronto Glacial Soils and implementation in numerical modelling in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper107,author = Masoud Manzari; Andrew Drevininkas; Dmitry Olshansky; Abdullah Galaa,title = Behavioural modelling of Toronto Glacial Soils and implementation in numerical modelling,year = 2014}