{"title":"A DEM study on the effects of specimen and particle sizes on direct simple shear tests","authors":"Mohammad Zeraati-Shamsabadi, Abouzar Sadrekarimi","doi":"10.1007/s10035-025-01513-y","DOIUrl":null,"url":null,"abstract":"<div><p>The direct simple shear (DSS) test serves as a vital method in geotechnics, allowing the measurement of peak and post-liquefaction shear strengths, along with the critical state friction angle of soils. Additionally, the simple shearing mode applied in a DSS test is the predominant failure mode in many geotechnical engineering problems. Although the DSS test is widely used to determine soil strength, a significant challenge with the DSS device is the non-uniformity of stress and strain distributions at the specimen boundaries. This non-uniformity depends on not only the specimen size but also the size of soil particles. The influence of specimen size on boundary effects is typically evaluated using the ratio of specimen diameter (<i>D</i>) to height (<i>H</i>). The median particle diameter (<i>D</i><sub><i>50</i></sub>), as an indicator of a soil’s particle size, could be another influential factor affecting the non-uniformities of stress and strain on specimen boundaries in a DSS test. Through three-dimensional discrete element method (DEM) simulations, this research explores these factors. Specimens were generated with a particle size distribution (PSD) scaled from a coarse sand sample. Laboratory monotonic DSS testing results on the coarse sand were employed to calibrate the DEM model and ascertain the modeling parameters. Boundary displacements were regulated to maintain a constant-volume condition which represents undrained shearing behavior. Various specimen diameters were simulated with identical void ratios to investigate the influence of <i>D/H</i> on stress path, peak and post-peak shear strengths, and critical state behavior. DEM simulations allowed the generation of several particle size distributions through different scaling factors applied to the sand gradation to determine the combined effect <i>D</i><sub><i>50</i></sub> and <i>D/H</i>. Limiting <i>D/H</i> and <i>D</i><sub><i>50</i></sub><i>/D</i> ratios are subsequently proposed to mitigate specimen boundary effects.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"27 2","pages":""},"PeriodicalIF":2.4000,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Granular Matter","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s10035-025-01513-y","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The direct simple shear (DSS) test serves as a vital method in geotechnics, allowing the measurement of peak and post-liquefaction shear strengths, along with the critical state friction angle of soils. Additionally, the simple shearing mode applied in a DSS test is the predominant failure mode in many geotechnical engineering problems. Although the DSS test is widely used to determine soil strength, a significant challenge with the DSS device is the non-uniformity of stress and strain distributions at the specimen boundaries. This non-uniformity depends on not only the specimen size but also the size of soil particles. The influence of specimen size on boundary effects is typically evaluated using the ratio of specimen diameter (D) to height (H). The median particle diameter (D50), as an indicator of a soil’s particle size, could be another influential factor affecting the non-uniformities of stress and strain on specimen boundaries in a DSS test. Through three-dimensional discrete element method (DEM) simulations, this research explores these factors. Specimens were generated with a particle size distribution (PSD) scaled from a coarse sand sample. Laboratory monotonic DSS testing results on the coarse sand were employed to calibrate the DEM model and ascertain the modeling parameters. Boundary displacements were regulated to maintain a constant-volume condition which represents undrained shearing behavior. Various specimen diameters were simulated with identical void ratios to investigate the influence of D/H on stress path, peak and post-peak shear strengths, and critical state behavior. DEM simulations allowed the generation of several particle size distributions through different scaling factors applied to the sand gradation to determine the combined effect D50 and D/H. Limiting D/H and D50/D ratios are subsequently proposed to mitigate specimen boundary effects.
期刊介绍：
Although many phenomena observed in granular materials are still not yet fully understood, important contributions have been made to further our understanding using modern tools from statistical mechanics, micro-mechanics, and computational science.
These modern tools apply to disordered systems, phase transitions, instabilities or intermittent behavior and the performance of discrete particle simulations.
>> Until now, however, many of these results were only to be found scattered throughout the literature. Physicists are often unaware of the theories and results published by engineers or other fields - and vice versa.
The journal Granular Matter thus serves as an interdisciplinary platform of communication among researchers of various disciplines who are involved in the basic research on granular media. It helps to establish a common language and gather articles under one single roof that up to now have been spread over many journals in a variety of fields. Notwithstanding, highly applied or technical work is beyond the scope of this journal.
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