Poisson’s ratio, besides its transverse-axial strain ratio definition, also plays a significant role in traditional elastic theory as an elastic constant. However, this elastic role of Poisson’s ratio faces a challenge when applied to quasi-elastic granular soils. A so-called “deformation ratio” is therefore introduced and measured in this paper for quasi-elastic granular soils. With the same definition of the transverse-axial strain ratio as Poisson’s ratio, the stress-state dependency of the deformation ratio and the break-down of conversion relationship of elastic constants are investigated under cyclic triaxial tests. The results show that Poisson’s ratio is consistent with deformation ratio only in the initial state of shear, and there is a non-negligible deviation in subsequent shear. The conversion relationship of elastic constants does not hold for the deformation ratio with increasing deviator stress. A special case is analyzed when the deformation ratio is greater than 0.5 and the specimen is subject to a shear elastic dilatancy. Discrete element simulations are conducted to clarify the microscopic mechanism of elastic dilatancy by tracking the evolution of the contact number of particles and the trajectory of the contact. This study provides new insights in understanding the elastic behavior of granular soils.

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Civil, Architectural and Environmental Engineering

Keywords and Phrases

Deformation Ratio; Poisson’s Ratio; Quasi-Elastic Deformation State; Elastic Dilatancy; Discrete Element Method; Cyclic Triaxial Tests; Digital Image Measurement

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Publication Date

08 Feb 2021