Discrete Element Modeling of Instability Mechanisms of Unbound Permeable Aggregate Base Materials in Triaxial Compression
Unbound permeable aggregate base (UPAB) materials with strong load-transmitting skeleton yet adequate inter-connected pores are desired for use in the sponge-city initiative. However, the micro-scale fabric evolution and instability mechanism of macroscopic strength behavior of such UPAB materials s...
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-04-01
|
| Series: | Materials |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1944/15/8/2716 |
| _version_ | 1797434430213586944 |
|---|---|
| author | Yuanjie Xiao Xiaoming Wang Qunding Yu Juanjuan Ren Wenjun Hua Ralina Mustafina Fuguang Zhang Huaiping Feng Tongwen Zhang |
| author_facet | Yuanjie Xiao Xiaoming Wang Qunding Yu Juanjuan Ren Wenjun Hua Ralina Mustafina Fuguang Zhang Huaiping Feng Tongwen Zhang |
| author_sort | Yuanjie Xiao |
| collection | DOAJ |
| description | Unbound permeable aggregate base (UPAB) materials with strong load-transmitting skeleton yet adequate inter-connected pores are desired for use in the sponge-city initiative. However, the micro-scale fabric evolution and instability mechanism of macroscopic strength behavior of such UPAB materials still remain unclear. In this study, virtual monotonic triaxial compression tests were conducted by using the discrete element method (DEM) modeling approach on specimens with different gradations quantified by the parameter of gravel-to-sand ratio (G/S). The realistic aggregate particle shape and inter-particle contact behavior were properly considered in the DEM model. The micromechanical mechanisms of the shearing failure of such UPAB materials and their evolution characteristics with G/S values were disclosed from contact force chains, microstructures, and particle motion. It was found that the proportion of rotating particles in the specimens decreased and the proportion of relative sliding between particles increased as the content of fine particles decreased. The plastic yielding of the specimens originated from the failure of contact force chains and the occurrence of the relative motion between particles, while the final instability was manifested by the large-scale relative motion among particles along the failure plane (i.e., changes in the internal particle topology). By comparing the macroscopic strength, microstructure evolution, and particle motion characteristics of the specimens with different G/S values, it was found that the specimens with G/S value of 1.8 performed the best, and that the G/S value of 1.8 could be regarded as the threshold for separating floating dense and skeletal gap type packing structures. The variation of Euler angles of rotating particles was significantly reduced in the particle size range of 4.75 mm to 9.50 mm, indicating that this size range separates most of the particles from rolling and sliding. Since particle rolling and sliding behavior are directly related to shear strength, this validates the rationality of the parameter G/S for controlling and optimizing gradations from the perspective of particle movement. The findings could provide theoretical basis and technical guidance for the effective design and efficient utilization of UPAB materials. |
| first_indexed | 2024-03-09T10:32:07Z |
| format | Article |
| id | doaj.art-8102e05e6ff94f8c9fbee1853b44cb62 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-09T10:32:07Z |
| publishDate | 2022-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-8102e05e6ff94f8c9fbee1853b44cb622023-12-01T21:10:25ZengMDPI AGMaterials1996-19442022-04-01158271610.3390/ma15082716Discrete Element Modeling of Instability Mechanisms of Unbound Permeable Aggregate Base Materials in Triaxial CompressionYuanjie Xiao0Xiaoming Wang1Qunding Yu2Juanjuan Ren3Wenjun Hua4Ralina Mustafina5Fuguang Zhang6Huaiping Feng7Tongwen Zhang8School of Civil Engineering, Central South University, Changsha 410075, ChinaSchool of Civil Engineering, Central South University, Changsha 410075, ChinaSchool of Civil Engineering, Central South University, Changsha 410075, ChinaSchool of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, ChinaSchool of Civil Engineering, Central South University, Changsha 410075, ChinaSchool of Civil Engineering, Central South University, Changsha 410075, ChinaState Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University, Shijiazhuang 050043, ChinaState Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University, Shijiazhuang 050043, ChinaSchool of Railway Engineering, Hunan Technical College of Railway High-Speed, Hengyang 421002, ChinaUnbound permeable aggregate base (UPAB) materials with strong load-transmitting skeleton yet adequate inter-connected pores are desired for use in the sponge-city initiative. However, the micro-scale fabric evolution and instability mechanism of macroscopic strength behavior of such UPAB materials still remain unclear. In this study, virtual monotonic triaxial compression tests were conducted by using the discrete element method (DEM) modeling approach on specimens with different gradations quantified by the parameter of gravel-to-sand ratio (G/S). The realistic aggregate particle shape and inter-particle contact behavior were properly considered in the DEM model. The micromechanical mechanisms of the shearing failure of such UPAB materials and their evolution characteristics with G/S values were disclosed from contact force chains, microstructures, and particle motion. It was found that the proportion of rotating particles in the specimens decreased and the proportion of relative sliding between particles increased as the content of fine particles decreased. The plastic yielding of the specimens originated from the failure of contact force chains and the occurrence of the relative motion between particles, while the final instability was manifested by the large-scale relative motion among particles along the failure plane (i.e., changes in the internal particle topology). By comparing the macroscopic strength, microstructure evolution, and particle motion characteristics of the specimens with different G/S values, it was found that the specimens with G/S value of 1.8 performed the best, and that the G/S value of 1.8 could be regarded as the threshold for separating floating dense and skeletal gap type packing structures. The variation of Euler angles of rotating particles was significantly reduced in the particle size range of 4.75 mm to 9.50 mm, indicating that this size range separates most of the particles from rolling and sliding. Since particle rolling and sliding behavior are directly related to shear strength, this validates the rationality of the parameter G/S for controlling and optimizing gradations from the perspective of particle movement. The findings could provide theoretical basis and technical guidance for the effective design and efficient utilization of UPAB materials.https://www.mdpi.com/1996-1944/15/8/2716unbound permeable aggregate basegradationdiscrete element methodshear strength behaviorfabric evolutionparticle movement |
| spellingShingle | Yuanjie Xiao Xiaoming Wang Qunding Yu Juanjuan Ren Wenjun Hua Ralina Mustafina Fuguang Zhang Huaiping Feng Tongwen Zhang Discrete Element Modeling of Instability Mechanisms of Unbound Permeable Aggregate Base Materials in Triaxial Compression Materials unbound permeable aggregate base gradation discrete element method shear strength behavior fabric evolution particle movement |
| title | Discrete Element Modeling of Instability Mechanisms of Unbound Permeable Aggregate Base Materials in Triaxial Compression |
| title_full | Discrete Element Modeling of Instability Mechanisms of Unbound Permeable Aggregate Base Materials in Triaxial Compression |
| title_fullStr | Discrete Element Modeling of Instability Mechanisms of Unbound Permeable Aggregate Base Materials in Triaxial Compression |
| title_full_unstemmed | Discrete Element Modeling of Instability Mechanisms of Unbound Permeable Aggregate Base Materials in Triaxial Compression |
| title_short | Discrete Element Modeling of Instability Mechanisms of Unbound Permeable Aggregate Base Materials in Triaxial Compression |
| title_sort | discrete element modeling of instability mechanisms of unbound permeable aggregate base materials in triaxial compression |
| topic | unbound permeable aggregate base gradation discrete element method shear strength behavior fabric evolution particle movement |
| url | https://www.mdpi.com/1996-1944/15/8/2716 |
| work_keys_str_mv | AT yuanjiexiao discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression AT xiaomingwang discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression AT qundingyu discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression AT juanjuanren discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression AT wenjunhua discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression AT ralinamustafina discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression AT fuguangzhang discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression AT huaipingfeng discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression AT tongwenzhang discreteelementmodelingofinstabilitymechanismsofunboundpermeableaggregatebasematerialsintriaxialcompression |