Dynamic properties of granular materials with varying coefficients of uniformity under cyclic shear and constrained compression from DEM simulations--颗粒学报PARTICUOLOGY

Song, J., Lai, Z., & He, J. (2025). Dynamic properties of granular materials with varying coefficients of uniformity under cyclic shear and constrained compression from DEM simulations. Particuology, 104, 153-164. https://doi.org/10.1016/j.partic.2025.06.013

Jian Song^*, Zehua Lai, Jiaqing He

Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing, 210098, China

10.1016/j.partic.2025.06.013

Volume 104, September 2025, Pages 153-164

Received 6 May 2025, Revised 17 June 2025, Accepted 26 June 2025, Available online 5 July 2025, Version of Record 10 July 2025.

E-mail: jiansonghh@163.com

Highlights

• Nonlinearity of stiffness and damping ratio of granular soils are studied based on DEM method.

• Effects of cyclic shear, constrained compression and particle size distributions are considered.

• Damping ratio under cyclic shear is much larger than cyclic constrained compression.

• Dynamic nonlinearity is more pronounced with increasing coefficient of uniformity.

• Link between particle contact and nonlinear stress-strain response is interpreted.

Abstract

Evaluation of dynamic soil properties under shear and compressional waves is an important concern in geotechnical earthquake engineering. In this work, the nonlinear strain-dependent behaviors of stiffness and damping properties of granular materials with different particle size distributions are studied using three-dimensional discrete element method. In particular, both nonlinear variations in shear and constrained modulus and associated damping ratios with strain are analyzed based on the simulations of cyclic triaxial and cyclic constrained compression tests. Micromechanical explorations on the influence of coefficient of uniformity (C_u) and the manner of cyclic loading are presented. The results indicate that the shear modulus exhibits a reduction relationship with shear strain in both triaxial compression and extension stages, whereas the constrained modulus only degrades during the extension stage. The damping ratio under cyclic triaxial loading is much larger than that under cyclic constrained compression. The dynamic nonlinearity under two types of cyclic loading is more pronounced with increasing C_u. The more significant modulus reduction with higher C_u correlates with a lower percentage of strong contact and a more heterogeneous distribution of strong contact normal forces. The increase in damping ratio with higher C_u is associated with a larger percentage of sliding contacts. The difference in damping ratio between cyclic triaxial and cyclic constrained compression tests is attributed to the different strain energy magnitudes that are required to the target shear and compression strain levels.

Graphical abstract

Keywords

Earthquake; Modulus reduction; Damping ratio; Granular material; Coefficient of uniformity; Discrete element method (DEM)

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