Effect of Imperfect Direct Simple Shear Test Boundary Conditions on Calibration of Constitutive Models

Daniel Wai, Mathan V. Manmatharajan, Thamer Yacoub, Mason Ghafghazi

In the proceedings of GeoSt. John's 2019: 72nd Canadian Geotechnical Conference

Session: Dynamic Properties of Soil

ABSTRACT: The direct simple shear (DSS) test is commonly used to calibrate constitutive models for various geotechnical problems. However, constitutive models are calibrated under the assumption of ideal simple shear stress conditions even though this is not achieved in the DSS test. Near frictionless vertical boundaries that enforce lateral confinement are not capable of inducing complementary shear stresses necessary for simple shear stress conditions. The effect of friction between the soil and vertical boundaries on stress distribution is not well studied and may impact the calibration of constitutive models. Undrained monotonic simple shear tests considering soil-ring interaction are simulated using finite element analyses. Simulations of the expected soil-ring friction compare well with ideal simple shear results despite stress non-uniformities near the vertical boundaries. Although higher soil-ring friction reduces stress non-uniformities during shearing, the friction develops stress non-uniformities during the consolidation phase that cannot be ignored when calibrating models.

RÉSUMÉ: cyclique en cisaillement simple est couramment utilisé afin de calibrer des modèles constitutifs. Toutefois, ces modèles constitutifs sont calibrés en assumant des conditions idéales de cisaillement simple qui ne se produisent pas lors limites verticales a un impact sur la distribution des contraintes qui présente étude, des essais en cisaillement simple monotoniques non-finis. Les résultats des simulations sont comparables à des conditions idéales de cisaillement simple même si le frottement entre le sol et les limites verticales cause des contraintes non-uniformes. Un frottement élevé entre le sol et les limites -peut pas être ignoré lors de la calibration de modèles constitutifs.

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Cite this article:
Daniel Wai; Mathan V. Manmatharajan; Thamer Yacoub; Mason Ghafghazi (2019) Effect of Imperfect Direct Simple Shear Test Boundary Conditions on Calibration of Constitutive Models in GEO2019. Ottawa, Ontario: Canadian Geotechnical Society.

@article{Geo2019Paper393,author = Daniel Wai; Mathan V. Manmatharajan; Thamer Yacoub; Mason Ghafghazi,title = Effect of Imperfect Direct Simple Shear Test Boundary Conditions on Calibration of Constitutive Models ,year = 2019}