Unified discrete-element approach applying arbitrary undrained loading paths in element testing for granular soils |
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| Authors: | Qixin Wu Zhongxuan Yang |
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| Institution: | 1. School of Civil Engineering, Wuhan University, Wuhan, China;2. Department of Civil Engineering, Zhejiang University, Hangzhou, China |
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| Abstract: | The discrete element method (DEM) is crucial in investigating and modeling the elementary behavior of granular materials under varying loading conditions, especially those that cannot be adequately investigated via conventional laboratory testing. However, the application of the DEM in simulations that involve complex loading paths under undrained conditions is scarce, primarily owing to the inability to maintain a constant-volume condition. This paper presents a unified discrete element approach that can apply arbitrary loading paths while satisfying the equivalent undrained condition. The proposed method comprises two parts: (1) a novel strategy that determines the virtual pore pressure under complex undrained loading conditions, and (2) an advanced undrained servomechanism that can simultaneously control each stress component independently. Numerical algorithms corresponding to three new undrained loading paths, that is, true triaxial test, rotational shear, and traffic loading path that have never been simulated using DEM are successfully implemented in a unified manner. Macroscale simulation results under these loading paths are qualitatively in good agreement with their experimental counterparts, thereby confirming the practicality and robustness of the proposed approach. Furthermore, in-depth discussions on the DEM results from these three new loading paths are presented from microscopic perspective. |
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| Keywords: | arbitrary stress paths discrete element method element tests equivalent pore pressure undrained response |
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