Granüler Malzemelerin Direkt Kayma Tepkisi Üzerindeki Parçacık Şekli ve Boyut Özelliklerinin Etkilerinin Çok Ölçekli DEM İncelemesi

Öz

Bu çalışma, granüler malzemelerin kayma davranışı üzerindeki tanecik şekli, boyutu ve boyut dağılımı etkilerini Ayrık Elemanlar Yöntemi (Discrete Element Method, DEM) tabanlı çok ölçekli bir yaklaşımla incelemektedir. İlk olarak, literatürdeki doğrudan kesme deneyi verileriyle doğrulanan bir DEM modeli geliştirilmiş, ardından sistematik biçimde farklı tanecik özelliklerine sahip yedi model analiz edilmiştir. Tanecik şeklinin etkisini belirlemek amacıyla, eş hacimli ancak farklı küresellik ve yuvarlaklık değerlerine sahip taneciklerden oluşan modeller oluşturulmuştur. Tanecik boyutu ve boyut dağılımının etkilerini değerlendirmek için farklı çaplara ve gradasyon katsayılarına (Cᵤ) sahip modeller analiz edilmiştir. Sonuçlar, tanecik şeklinin granüler sistemlerin hem makro hem mikro ölçekli davranışı üzerinde en belirleyici parametre olduğunu göstermiştir. Azalan küresellik ve yuvarlaklık, tepe dayanımını artırırken kesme sürecinde temas ağının daha hızlı çözülmesine yol açmıştır. Tanecik boyutu dayanımı ikinci derecede etkilemiş, bu etki çap azaldıkça artmış ancak belirli bir eşik değerin altında azalmıştır. Boyut dağılımı sınırlı bir etki göstermiş, tekdüzelik azaldıkça dilatansın hafifçe arttığı gözlenmiştir. Elde edilen bulgular, tanecik şeklinin granüler sistemlerin dayanım ve deformasyon mekanizmalarını belirleyen temel unsur olduğunu ortaya koymuştur.

Anahtar Kelimeler

• Ayrık Elemanlar Yöntemi (DEM)
• Granüler Malzemeler
• Tanecik Şekli
• Tanecik Boyutu
• Tanecik Boyut Dağılımı

Multi-scale DEM Investigation of the Effects of Particle Shape and Size Characteristics on the Direct Shear Response of Granular Materials

Abstract

This study investigates the impact of particle shape, size, and size distribution on the shear behavior of granular materials using a multiscale Discrete Element Method (DEM) approach. A DEM model validated against direct shear test data from the literature was first developed, and seven models with systematically varied particle properties were analyzed. To assess the influence of particle shape, models with equal-volume particles but different sphericity and roundness were used. The effects of particle size and size distribution were investigated through models containing particles of various diameters and gradation coefficients (Cᵤ). The results demonstrated that particle shape exerts the most significant influence on both macro- and microscale behavior. Decreasing sphericity and roundness increased peak shear strength but led to a faster breakdown of contact networks during shearing. Particle size was the second most influential parameter; its effect intensified as size decreased but diminished below a threshold diameter. Particle size distribution showed a minor effect, with a slight increase in dilatancy observed as uniformity decreased. Correlating macroscale stress–strain responses with microscale coordination number changes confirmed that particle shape is the dominant factor controlling the strength and deformation mechanisms of granular systems.

Keywords

• Discrete Element Method (DEM)
• Granular Materials
• Particle Shape
• Particle Size
• Particle Size Distribution

Kaynakça

1. Ahmed, S. S., Martinez, A., & DeJong, J. (2024). Gradation and state effects on the strength and dilatancy of coarse-grained soils. E3S Web of Conferences, 544, 13003. https://doi.org/10.1051/e3sconf/202454413003
2. Altair Engineering Inc. (2022). Altair EDEM 2022: Discrete Element Method software for bulk and granular material simulation. Troy, MI, USA: Altair Engineering Inc.
3. Altuhafi, F. N., Coop, M. R., & Georgiannou, V. N. (2016). Effect of Particle Shape on the Mechanical Behavior of Natural Sands. Journal of Geotechnical and Geoenvironmental Engineering, 142(12). https://doi.org/10.1061/(ASCE)GT.1943-5606.0001569
4. Azéma, E., & Radjaï, F. (2010). Stress-strain behavior and geometrical properties of packings of elongated particles. Physical Review E, 81(5), 051304. https://doi.org/10.1103/PhysRevE.81.051304
5. Barton, N., & Kjærnsli, B. (1981). Shear Strength of Rockfill. Journal of the Geotechnical Engineering Division, 107(7), 873–891. https://doi.org/10.1061/AJGEB6.0001167
6. Bisht, M. C., & Bhutani, G. (2023). A New Code for Discrete Element Modelling of the Collapse of Granular Columns—Model Validation. https://doi.org/10.1007/978-981-19-6970-6_7
7. Cao, P., Jiang, M., & Ding, Z. (2020). Effects of particle size on mechanical behaviors of calcareous sand under triaxial conditions. Japanese Geotechnical Society Special Publication, 8(5), 182–187. https://doi.org/10.3208/jgssp.v08.c54
8. Carrasco, S., Cantor, D., Ovalle, C., & Dubois, F. (2025). Particle shape distribution effects on the critical strength of granular materials. Computers and Geotechnics, 177, 106896. https://doi.org/10.1016/j.compgeo.2024.106896

9. Chen, J., Indraratna, B., Vinod, J. S., Ngo, T., & Liu, Y. (2025). Effects of Particle Shape on the Shear Behavior and Breakage of Ballast: A DEM Approach. International Journal of Geomechanics, 25(1). https://doi.org/10.1061/IJGNAI.GMENG-9617
10. Cho, G.-C., Dodds, J., & Santamarina, J. C. (2006). Particle Shape Effects on Packing Density, Stiffness, and Strength: Natural and Crushed Sands. Journal of Geotechnical and Geoenvironmental Engineering, 132(5), 591–602. https://doi.org/10.1061/(ASCE)1090-0241(2006)132:5(591)
11. Cui, L., & O’Sullivan, C. (2006). Exploring the macro- and micro-scale response of an idealised granular material in the direct shear apparatus. Géotechnique, 56(7), 455–468. https://doi.org/10.1680/geot.2006.56.7.455
12. Cundall, P. A., & Strack, O. D. L. (1979). A discrete numerical model for granular assemblies. Géotechnique, 29(1), 47–65. https://doi.org/10.1680/geot.1979.29.1.47
13. El-Kassem, B., Salloum, N., Brinz, T., Heider, Y., & Markert, B. (2021). A multivariate regression parametric study on DEM input parameters of free-flowing and cohesive powders with experimental data-based validation. Computational Particle Mechanics, 8(1), 87–111. https://doi.org/10.1007/s40571-020-00315-8
14. Gezgin, A. T., Çinicioğlu, S. F., & Çinicioğlu, Ö. (2023). Discrete Element Modeling of Open Ended Pile Penetration in Granular Medium (in Turkish). 9th Geotechnical Symposium. İstanbul, Türkiye.
15. Gezgin, A. T., Soltanbeigi, B., & Çinicioğlu, Ö. (2022). Techniques to Reduce Computational Time in Discrete Element Method: Penetration Modelling in Granular Soils (in Turkish). 18th National Congress on Soil Mechanics and Geotechnical Engineering. Kayseri, Türkiye.
16. Härtl, J., & Ooi, J. Y. (2008). Experiments and simulations of direct shear tests: porosity, contact friction and bulk friction. Granular Matter, 10(4), 263–271. https://doi.org/10.1007/s10035-008-0085-3
17. Ioannidi, P. I., McLafferty, S., Reber, J. E., Morra, G., & Weatherley, D. (2024). Deformation and Frictional Failure of Granular Media in 3D Analog and Numerical Experiments. Pure and Applied Geophysics, 181(7), 2083–2105. https://doi.org/10.1007/s00024-024-03464-6
18. Iwashita, K., & Oda, M. (1998). Rolling Resistance at Contacts in Simulation of Shear Band Development by DEM. Journal of Engineering Mechanics, 124(3), 285–292. https://doi.org/10.1061/(ASCE)0733-9399(1998)124:3(285)
19. Jiang, M., Yin, Z.-Y., & Shen, Z. (2016). Shear band formation in lunar regolith by discrete element analyses. Granular Matter, 18(2), 32. https://doi.org/10.1007/s10035-016-0635-z
20. Jouannot-Chesney, P., Jernot, J.-P., & Lantuéjoul, C. (2011). Practical Determination of the Coordination Number in Granular Media. Image Analysis & Stereology, 25(1), 55. https://doi.org/10.5566/ias.v25.p55-61
21. La Ragione, L., & Magnanimo, V. (2012). Contact anisotropy and coordination number for a granular assembly: A comparison of distinct-element-method simulations and theory. Physical Review E, 85(3), 031304. https://doi.org/10.1103/PhysRevE.85.031304
22. Marsal, R. J. (1967). Large Scale Testing of Rockfill Materials. Journal of the Soil Mechanics and Foundations Division, 93(2), 27–43. https://doi.org/10.1061/JSFEAQ.0000958
23. Ovalle, C., Frossard, E., Dano, C., Hu, W., Maiolino, S., & Hicher, P.-Y. (2014). The effect of size on the strength of coarse rock aggregates and large rockfill samples through experimental data. Acta Mechanica, 225(8), 2199–2216. https://doi.org/10.1007/s00707-014-1127-z
24. Thornton, C., & Zhang, L. (2003). Numerical Simulations of the Direct Shear Test. Chemical Engineering & Technology, 26(2), 153–156. https://doi.org/10.1002/ceat.200390022
25. Wang, Z.-Y., Wang, P., Yin, Z.-Y., & Wang, R. (2022). Micromechanical investigation of the particle size effect on the shear strength of uncrushable granular materials. Acta Geotechnica, 17(10), 4277–4296. https://doi.org/10.1007/s11440-022-01501-z
26. Xu, R., Liu, E., & Li, J. (2024). Multiscale Analysis of Mechanical Properties and Kinetic Processes in Dry Granular Flow. Advances in Civil Engineering, 2024(1). https://doi.org/10.1155/adce/4348417
27. Yilmaz, Y., Deng, Y., Chang, C. S., & Gokce, A. (2023). Strength–dilatancy and critical state behaviours of binary mixtures of graded sands influenced by particle size ratio and fines content. Géotechnique, 73(3), 202–217. https://doi.org/10.1680/jgeot.20.P.320
28. Yu, W., Wang, S., & Miao, Y. (2023). Characterizing force-chain network in aggregate blend using discrete element method and complex network theory. Construction and Building Materials, 400, 132724. https://doi.org/10.1016/j.conbuildmat.2023.132724
29. Zhao, L.-L., Zhu, Z.-F., Zhao, Y.-M., Zheng, Q.-J., Xu, F., Wang, W., … Duan, C.-L. (2024). Laboratory-scale validation of a DEM model for the cross-screen processes of wet coals. Powder Technology, 431, 119091. https://doi.org/10.1016/j.powtec.2023.119091