Application of discrete element modeling for simulation of cyclic direct simple shear response of granular materials
Bibliographic record
Abstract
The Discrete Element Method (DEM) has been increasingly used to simulate and study the fundamental behavior of granular materials. This is due to the ability of the method to model soils as a collection of particles, which is considered more realistic compared to assuming soils as a continuum. The recent advances in computational capabilities along with the development of efficient DEM algorisms has made it possible to simulate problems with reasonable number of particles, and to develop more realistic 3D models. For example, DEM has been successfully used to model soil response under boundary conditions similar to those used in soil laboratory testing particularly under triaxial and direct shear (i.e. shear box) monotonic loading conditions. So far, only limited DEM analysis has been performed to simulate soil response under cyclic loading conditions. With this background, and considering the known common use of the Direct Simple Shear (DSS) test in characterising soil behavior particularly under cyclic loading conditions, DEM simulations of the cyclic DSS test were performed using Particle Flow Code in Three Dimensions (PFC3D) Version 3.1. In this paper, the results of the DEM simulations are compared with data from counterpart laboratory element cyclic shear testing performed using the NGI-type DSS device at the University of British Columbia (UBC), Vancouver, Canada. The stress paths obtained from the results of simulated DSS constant volume (i.e. equivalent to undrained) tests indicated an overall reduction of vertical effective stress with the progression of cyclic loading. In the simulations conducted representing loose granular material, relatively smaller shear strains were noted during the first loading cycle; whereas, a transient vertical effective stress value close to zero was developed along with an abrupt increase in shear strain during the last loading cycle. These results are much in accord with those observed from experimental testing of loose sands. This noted agreement between the results of the physical and numerical models suggests the suitability of DEM for use in modeling the cyclic response of granular materials.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".