Article
Engineering, Geological
Ehsan Badakhshan, Ali Noorzad, Abdelmalek Bouazza, Chaoshui Xu
Summary: This study investigates the anisotropic behavior of geo-materials using the discrete element method (DEM), proposing a particle stiffness fabric tensor (P-S fabric) to characterize the internal structure of particles associated with anisotropy. Results show that the proposed approach offers effective modeling of rocks' anisotropic behavior, with better agreement with experimental results compared to conventional numerical modeling approaches.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Geological
Xiaoqiang Gu, Youhong Li, Jing Hu, Zhenhao Shi, Fayun Liang, Maosong Huang
Summary: Natural clays exhibit anisotropic stiffness and fabric due to their deposition process and in situ stress state. This paper measured the K0 value and elastic shear stiffness anisotropy of Shanghai clay and proposed empirical equations to estimate these values. The experimental data analysis revealed the increase in stiffness anisotropy and nearly constant fabric anisotropy during K0 consolidation.
Article
Computer Science, Interdisciplinary Applications
An Zhang, Mingjing Jiang, Dong Wang
Summary: To understand the effects of fabric anisotropy on cyclic liquefaction of sands, undrained cyclic triaxial tests on vertical and horizontal specimens were simulated using the discrete element method. The simulation accurately depicted the anisotropic cyclic responses observed in experiments, showing that the vertical specimen is more susceptible to liquefaction than the horizontal specimen under symmetrical cyclic loading conditions. The study investigated various fabric parameters at the particle scale to gain insights into the macro response and applied anisotropic critical state theory to explore the relationship between macro-mechanical behavior and fabric evolution.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Chemistry, Multidisciplinary
Jiangu Qian, Chuang Zhou, Weiyi Li, Xiaoqiang Gu, Yongjun Qin, Liangfu Xie
Summary: This study uses the discrete element method to simulate shear tests and reveals the key factors influencing K-0 of granular materials. The results show that particle shape, initial void ratio, and inter-particle friction angle significantly affect K-0 values. Based on the experimental results, a more accurate empirical equation is proposed that considers the effect of particle shape.
APPLIED SCIENCES-BASEL
(2022)
Article
Mathematics, Interdisciplinary Applications
Manogna Adepu, Shaohua Chen, Yang Jiao, Aytekin Gel, Heather Emady
Summary: The study found that different heat transfer coefficients result from the variability in particle size distribution with the same mean and standard deviation. Monodispersed particle beds exhibit better heat transfer compared to polydispersed beds. Rotation speed has minimal impact on conduction heat transfer, while better heat transfer is achieved at lower values of rolling friction.
COMPUTATIONAL PARTICLE MECHANICS
(2021)
Article
Engineering, Geological
Yuxuan Wen, Yida Zhang
Summary: This study uses the discrete element method to conduct a series of tests and finds a tight correlation between the void ratio and the fabric tensor of granular soils. By plotting the void ratio data against the first two invariants of the fabric tensor, a unique surface is obtained. The robustness of this relation is confirmed through testing samples with different initial void ratios under complex loading paths.
Article
Engineering, Geological
Xiaoqiang Gu, Xiaomin Liang, Jing Hu
Summary: Fabric anisotropy is a sought-after micro index to correlate macro mechanical responses of granular materials. In this work, discrete element method (DEM) is utilized to simulate multi-directional bender element tests in granular soils to obtain the evolution of wave velocities during drained conventional triaxial (CT) and true triaxial (TT) tests, and the contact normal based fabric is simultaneously monitored for bridging the fabric anisotropy and wave velocity anisotropy. The results show that stress-normalized wave velocities and microscopic fabric, including contact normal distribution and coordination number, remain nearly constant until a stress ratio threshold is reached. After the threshold value is reached, stress-normalized wave velocities start to decrease, especially in the minor principal stress direction, accompanied by significant adjustment of coordination number and fabric anisotropy. The results also reveal that the normalized wave velocity depends on the contact normal densities in the wave propagation and particle oscillation directions. With the contact normal distribution represented by a density function, a good linear relationship between the microscopic fabric anisotropy and macroscopic wave velocity anisotropy is obtained for both CT and TT tests.
Article
Engineering, Multidisciplinary
Pin Zhang, Zhen-Yu Yin
Summary: This study introduces a novel deep learning-based strategy to accurately identify the mechanical properties and fabric evolutions of granular samples using particle information from photos. By utilizing CNN and BiLSTM neural networks, the study successfully captures the mechanical behaviors and induced fabric evolutions of granular materials.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Engineering, Geological
Yuxuan Wen, Yida Zhang
Summary: This study introduces the concept of critical fabric surface (CFS) and establishes a single CFS spanning across a wide range of coordination numbers. This provides a new perspective to interpret and model the mechanics of granular soils in both pre- and post-liquefied regimes.
Article
Computer Science, Interdisciplinary Applications
Ming Xu, Jinwu Guo
Summary: The research using the discrete element method to simulate the development of lateral earth pressure of granular materials under cyclic loading found that lateral stresses increase continuously for both loose and dense samples during cycling. The unique relationship between deviator stress ratio on the macro-scale and deviator fabric of strong contacts on the micro-scale was revealed through micro response investigation. The influence of particle shape on macro and micro responses was highlighted through lateral cyclic loading tests on samples with spherical particles.
COMPUTERS AND GEOTECHNICS
(2021)
Article
Engineering, Chemical
Bei-Bing Dai, Tian-Qi Li, Lin-Jie Deng, Jun Yang, Wei-Hai Yuan
Summary: In this study, the effect of fabric orientation on the angle of repose was examined through physical experiments and numerical simulations. The results showed that the angle of repose first decreased and then rebounded as the deposition plane's orientation angle varied. The minimum values were observed at specific angles. Numerical analyses revealed the intensification of microstructure reorganization and the decrease in anisotropy magnitude. Based on a conceptual model, the fundamentals underlying the effect of fabric orientation on the angle of repose were clarified.
Article
Engineering, Geological
Jiangtao Wei
Summary: Numerical tests in DEM simulations were conducted to explore the evolution of particle-void fabric in granular packings during cyclic liquefaction. As the mean effective stress decreases during the process, the particle-void descriptor also decreases, showing a positive correlation between them.
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
(2022)
Article
Engineering, Geological
Subha Ghosh, Arghya Deb
Summary: This paper compares the role of material fabric in unconfined concrete and concrete subjected to external confinement. In unconfined concrete, the material fabric is the main reason for the early onset of shear bands. In confined specimens, fabric isotropy is more suited to capture the benefits of external confinement.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2022)
Article
Engineering, Chemical
Jiawei Han, Kai Shen, Yu Guo, Hongbing Xiong, Jianzhong Lin
Summary: A flexible ribbon-like particle model based on the Discrete Element Method (DEM) is developed for numerical modeling of biomass materials and other flexible materials. The model accurately simulates the uniaxial compression of biomass materials and investigates the effects of initial particle configuration, particle shape distribution, and particle size distribution on macroscopic and micro-structural properties.
Article
Mechanics
Subha Ghosh, Arghya Deb
Summary: This study extends the formal structure analysis to cemented granular materials and finds that the microstructural stress and strain show different effects on material performance in terms of isotropic and anisotropic parts.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2021)
