Evaluation of strain level and frequency effects on the dynamic properties of sand

Zahid Khan, Soheil Moayerian, Giovanni Cascante, Murray Grabinsky

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Earthquake Engineering & Geophysics

ABSTRACT: Dynamic properties of soils are critical for the design of structures subjected to vibrations. These properties can be measured from the transfer function between the excitation and the response using the resonant column device. The force function generated by a sinusoidal sweep excitation induces different shear strain levels at different frequencies. Consequently, the shape of the measured transfer function is distorted and differs from the theoretical transfer function for an equivalent single-degree-of-freedom system. The difference between the measured and assumed transfer functions becomes more pronounced with the increase in shear strain levels. This study presents a new methodology for the evaluation of dynamic properties from an improved transfer function. In this methodology, the soil specimen is excited using a fixed sine at the required strain level along with a simultaneous excitation of small amplitude random noise. The strain level induced by the fixed sine controls the resonant frequency and damping coefficient of the specimen whereas the random noise controls the shape of transfer function. The new methodology also shows a good potential for the evaluation of dynamic properties of soils as function of frequency in resonant column testing.

RÉSUMÉ: De nombreux problèmes géotechniques tels que la conception de systèmes résistants aux séismes et les vibrations de machines requièrent contrôler des vibrations excessives. Cette édes essais à colonne résonnante sur le sol synthétique. Le taux une quantité contrôlée de matériau viscoélastique dans le sable. Les essais à colonne résonnante indiquent que le taux le module de cisaillement.

Please include this code when submitting a data update: GEO2011_609

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