Finite/Discrete Element Modeling (FDEM) Of Time-Dependent Swelling Mechanisms in Southern Ontario Shales

Yusheng Qiu, Karl Peterson, Johnson Ha, Giovanni Grasselli

In the proceedings of: GeoOttawa 2017: 70th Canadian Geotechnical Conference; 12th joint with IAH-CNC

Session: Rock Mechanics III

ABSTRACT: Recent advances in modeling time-dependent swelling behaviour furthers the current understanding of excavations in shale dominated ground conditions of southern Ontario. This work presents the preliminary results of research that aims to develop a hybrid micromechanical finite/discrete element modeling (FDEM) approach to model tunneling in shale. Coupled with nanoindentation testing for calibration of material strength parameters, the micromechanical framework for material deformation in FDEM can define single element behaviour and account for heterogeneity of varying scales. The time-dependent swelling strain relations established through the works of Hawlader, Lee and Lo (2003), have been implemented into a FDEM framework by converting, at single element scale, the time-dependent swelling strains as additional volumetric strain components to the nodal solver. In addition, implementation of the swelling formulation into current FDEM methods can address potential dynamic interactions in evaluating tunnel stability, where the proposed addition to FDEM can incorporate additional capabilities of applying structural anisotropy to the model which are integral to shale lithologies. Following implementation at the single element scale, upscaling models to simulate a field scale tunnel excavation are used to demonstrate the proposed FDEM application as proof of concept for tunnel convergence due to swelling.

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Cite this article:
Yusheng Qiu; Karl Peterson; Johnson Ha; Giovanni Grasselli (2017) Finite/Discrete Element Modeling (FDEM) Of Time-Dependent Swelling Mechanisms in Southern Ontario Shales in GEO2017. Ottawa, Ontario: Canadian Geotechnical Society.

@article{geo2017Paper686,author = Yusheng Qiu; Karl Peterson; Johnson Ha; Giovanni Grasselli,title = Finite/Discrete Element Modeling (FDEM) Of Time-Dependent Swelling Mechanisms in Southern Ontario Shales,year = 2017}