Observations on the effect of strain rate and loading rate on monotonic and cyclic direct simple shear response of reconstituted Fraser River silts

Achala Soysa, Dharma Wijewickreme

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

Session: Dynamic Properties of Soil

ABSTRACT: The influence of the shearing rate on the response of sand as well as clay has been investigated and well-documented; however, such investigations on silt, especially the studies on the effects of strain/loading rates in the available literature is very limited. With this background, a series of constant-volume direct simple shear tests were conducted on reconstituted Fraser River silt with the objective of examining the effects of different strain and shear loading rates. This paper presents the results of strain-controlled monotonic direct simple shear tests with varying strain rates of 2%, 10% and 150% shear strain per hour; constant-amplitude sinusoidal stress-controlled cyclic shearing with loading cycle periods of 5 s, 10 s, 100 s, and 1000 s were also conducted. The experimental results indicate no significant variations in the peak shear resistance due to the different strain rate selected in monotonic shearing. However, increasing cyclic shear resistance tendency could be observed for increasing loading frequency (decreasing loading period). The observed characteristics on pore-water pressure development, shear strain accumulation, shear stiffness reduction/degradation and damping are presented and discussed with respect to the strain and loading rates.

RÉSUMÉ: L'influence du taux de cisaillement sur la réponse du sable ainsi que sur l'argile a été étudiée et bien rapportée. Cependant, ces études sur le limon, les études sur les effets des taux de contrainte / charge dans la littérature disponible sont très constant ont été menées sur des spécimens de limon reconstitués du Fraser, dans leffets de différentes vitesses de déformation et de charge de cisaillement. Cet article présente les résultats d'essais de cisaillement simple, direct, monotones et contrôlés par contrainte, avec différentes vitesses de contrainte, telles que des contraintes de cisaillement de 2%, 10% et 150% par heure; un cisaillement cyclique contrôlé par une contrainte sinusoïdale d'amplitude constante avec des périodes de cycle de chargement de 5, 10, 100 et 1000. Les résultats expérimentaux classées dans le cisaillement monotone. Cependant, une tendance croissante à la résistance au cisaillement cyclique a pu être observée pour une fréquence de charge croissante (période de charge décroissante).

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Cite this article:
Achala Soysa; Dharma Wijewickreme (2019) Observations on the effect of strain rate and loading rate on monotonic and cyclic direct simple shear response of reconstituted Fraser River silts in GEO2019. Ottawa, Ontario: Canadian Geotechnical Society.

@article{Geo2019Paper409,author = Achala Soysa; Dharma Wijewickreme,title = Observations on the effect of strain rate and loading rate on monotonic and cyclic direct simple shear response of reconstituted Fraser River silts,year = 2019}