Pub Date : 2026-01-01DOI: 10.1016/j.trgeo.2025.101833
Yang Xiao , Tingting Zhang , Qingyun Fang , Ninghao Wang , Shuang Liu , Hanlong Liu
The mechanical characteristics of clayey sands are crucial for evaluating behaviors pertinent to temperature-related geotechnical engineering. The undrained triaxial shear response of clayey sands, characterized by a constant skeleton void ratio, is experimentally investigated under varying fines contents, temperatures, and initial mean effective stresses. The effects of fines content and temperature on heating induced volumetric strain, peak deviatoric stress, peak excess pore water pressure, stress ratio at the undrained instability state, and collapsibility index are comprehensively investigated. Furthermore, a unified critical state line is proposed in the equivalent intergranular void ratio versus mean effective stress plane for clean sands, sand-slit mixtures, and sand-clay mixtures, irrespective of temperature. Additionally, the equivalent intergranular state parameter can be utilized to predict the mechanical responses of binary mixtures under both undrained instability state and critical state. It is valuable to use the equivalent skeleton void ratio to assess the stability in thermally influenced geotechnical engineering involving binary mixtures, particularly sand-dominated mixtures.
{"title":"Non-Isothermal Mechanical Response of Clayey Sands","authors":"Yang Xiao , Tingting Zhang , Qingyun Fang , Ninghao Wang , Shuang Liu , Hanlong Liu","doi":"10.1016/j.trgeo.2025.101833","DOIUrl":"10.1016/j.trgeo.2025.101833","url":null,"abstract":"<div><div>The mechanical characteristics of clayey sands are crucial for evaluating behaviors pertinent to temperature-related geotechnical engineering. The undrained triaxial shear response of clayey sands, characterized by a constant skeleton void ratio, is experimentally investigated under varying fines contents, temperatures, and initial mean effective stresses. The effects of fines content and temperature on heating induced volumetric strain, peak deviatoric stress, peak excess pore water pressure, stress ratio at the undrained instability state, and collapsibility index are comprehensively investigated. Furthermore, a unified critical state line is proposed in the equivalent intergranular void ratio versus mean effective stress plane for clean sands, sand-slit mixtures, and sand-clay mixtures, irrespective of temperature. Additionally, the equivalent intergranular state parameter can be utilized to predict the mechanical responses of binary mixtures under both undrained instability state and critical state. It is valuable to use the equivalent skeleton void ratio to assess the stability in thermally influenced geotechnical engineering involving binary mixtures, particularly sand-dominated mixtures.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"56 ","pages":"Article 101833"},"PeriodicalIF":5.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.trgeo.2025.101830
Zhizao Bao , Peng Chen , Xiaohua Bao , Jun Shen , Hongzhi Cui , Xiangsheng Chen
To address the dual challenges of areca waste disposal and subgrade performance enhancement, this study explores the feasibility of using areca fibers (AFs) as a sustainable reinforcement material for soft clay in transportation infrastructure. A series of consolidated undrained (CU) triaxial shear tests and cyclic triaxial tests were conducted to evaluate the static and dynamic behavior of AFs-reinforced soils under varying compaction conditions. In addition, a life cycle assessment (LCA) based carbon–force integrated evaluation model was established to quantify the carbon reduction benefits of AFs-reinforced soil in subgrade replacement applications. Experimental results show that under high compaction conditions, incorporating 2% AFs increases the shear strength of soil by 17% and the secant modulus by 65%. Under cyclic loading, the inclusion of AFs effectively restrains particle displacement and improves the dynamic stability of the soil. The LCA results indicate that AFs-reinforced soil achieves a carbon emission reduction exceeding 8.1% during the material production and construction stages, demonstrating clear environmental advantages. Comprehensive evaluation results reveal that soil reinforced with 2% AFs achieves the best balance between mechanical performance and carbon emissions, making it a promising alternative for sustainable subgrade engineering. This study offers both theoretical insights and practical guidance for the resource utilization of areca waste in geotechnical engineering, with a particular focus on its application in sustainable subgrade construction using AFs-reinforced soils.
{"title":"Sustainable subgrade reinforcement using areca fiber-reinforced soil: mechanical behavior and carbon emission evaluation","authors":"Zhizao Bao , Peng Chen , Xiaohua Bao , Jun Shen , Hongzhi Cui , Xiangsheng Chen","doi":"10.1016/j.trgeo.2025.101830","DOIUrl":"10.1016/j.trgeo.2025.101830","url":null,"abstract":"<div><div>To address the dual challenges of areca waste disposal and subgrade performance enhancement, this study explores the feasibility of using areca fibers (AFs) as a sustainable reinforcement material for soft clay in transportation infrastructure. A series of consolidated undrained (CU) triaxial shear tests and cyclic triaxial tests were conducted to evaluate the static and dynamic behavior of AFs-reinforced soils under varying compaction conditions. In addition, a life cycle assessment (LCA) based carbon–force integrated evaluation model was established to quantify the carbon reduction benefits of AFs-reinforced soil in subgrade replacement applications. Experimental results show that under high compaction conditions, incorporating 2% AFs increases the shear strength of soil by 17% and the secant modulus by 65%. Under cyclic loading, the inclusion of AFs effectively restrains particle displacement and improves the dynamic stability of the soil. The LCA results indicate that AFs-reinforced soil achieves a carbon emission reduction exceeding 8.1% during the material production and construction stages, demonstrating clear environmental advantages. Comprehensive evaluation results reveal that soil reinforced with 2% AFs achieves the best balance between mechanical performance and carbon emissions, making it a promising alternative for sustainable subgrade engineering. This study offers both theoretical insights and practical guidance for the resource utilization of areca waste in geotechnical engineering, with a particular focus on its application in sustainable subgrade construction using AFs-reinforced soils.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"56 ","pages":"Article 101830"},"PeriodicalIF":5.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Unsealed roads make up over 65% of Australia’s transport network and are prone to surface deterioration, such as corrugation, especially under dry climatic conditions. Corrugation formation is closely associated with progressive shear failure in the surface layer, often exacerbated by moisture loss. Crushed rock class IV material is widely used for unsealed road construction in Australia. The unsaturated shear strength behaviour of this material has not been characterised properly. This study presents a systematic experimental investigation into the unsaturated properties of compacted crushed rock class IV, focusing on the role of degree of saturation and fines content. Laboratory indirect tensile and direct shear tests were conducted on specimens compacted at optimum moisture content and subsequently dried back to a wide range of saturation levels. Results demonstrate a strongly nonlinear relationship between shear strength and degree of saturation, with cohesion peaking at intermediate saturation (around 40 %–50 %) and diminishing under both very dry and near-saturated states. The apparent friction angle increased with drying, reaching a peak at fully dry conditions. Comparison of fines-included and fines-removed specimens highlights the critical role of fines in generating suction-related cohesion and maintaining structural stability, as the specimens containing fines exhibited higher unsaturated cohesion. Nonlinear failure envelopes and an empirical Gaussian-based cohesion model are proposed to capture saturation-dependent behaviour, addressing limitations of conventional linear Mohr–Coulomb analyses. Practically, the results suggest that maintaining moisture within intermediate ranges and preserving fines during grading are essential strategies for improving the durability and performance of unsealed roads.
{"title":"Nonlinear unsaturated shear strength behaviour of compacted crushed rock class IV material: implications for corrugation in unsealed roads","authors":"Havisanth Erasanayagam , Liuxin Chen , Amir Tophel , Jayantha Kodikara","doi":"10.1016/j.trgeo.2025.101883","DOIUrl":"10.1016/j.trgeo.2025.101883","url":null,"abstract":"<div><div>Unsealed roads make up over 65% of Australia’s transport network and are prone to surface deterioration, such as corrugation, especially under dry climatic conditions. Corrugation formation is closely associated with progressive shear failure in the surface layer, often exacerbated by moisture loss. Crushed rock class IV material is widely used for unsealed road construction in Australia. The unsaturated shear strength behaviour of this material has not been characterised properly. This study presents a systematic experimental investigation into the unsaturated properties of compacted crushed rock class IV, focusing on the role of degree of saturation and fines content. Laboratory indirect tensile and direct shear tests were conducted on specimens compacted at optimum moisture content and subsequently dried back to a wide range of saturation levels. Results demonstrate a strongly nonlinear relationship between shear strength and degree of saturation, with cohesion peaking at intermediate saturation (around 40 %–50 %) and diminishing under both very dry and near-saturated states. The apparent friction angle increased with drying, reaching a peak at fully dry conditions. Comparison of fines-included and fines-removed specimens highlights the critical role of fines in generating suction-related cohesion and maintaining structural stability, as the specimens containing fines exhibited higher unsaturated cohesion. Nonlinear failure envelopes and an empirical Gaussian-based cohesion model are proposed to capture saturation-dependent behaviour, addressing limitations of conventional linear Mohr–Coulomb analyses. Practically, the results suggest that maintaining moisture within intermediate ranges and preserving fines during grading are essential strategies for improving the durability and performance of unsealed roads.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"57 ","pages":"Article 101883"},"PeriodicalIF":5.5,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-31DOI: 10.1016/j.trgeo.2025.101889
Mehdi Koohmishi , David P. Connolly
This paper presents an artificial intelligence (AI)-based approach to automate the structural health monitoring (SHM) of railway ballast through the fusion of long short-term memory and XGBoost (LSTM-XGB) to surface temperature data derived from infrared thermal images. In this context, machine learning models are trained using remotely acquired surface temperature data to classify fouling index based on thermal variations within ballast aggregates captured from thermograms. The long short-term memory (LSTM) component processes sequential time-series thermal data to predict preceding values, and the XGBoost (XGB) component classifies fouled ballast conditions based on identified patterns of surface temperature variations measured via infrared thermography (IRT). The results confirm the capability of the LSTM component to capture the time-series variations of a specimen’s surface temperature in a shorter timeframe as well as the superior performance of XGBoost compared to a random forest (RF) approach, in classifying fouled ballast conditions. Therefore, the LSTM-XGB model demonstrates higher efficiency compared to the standalone XGBoost model, since the predictive nature of LSTM over time-series temperature data enables capturing shorter time window for measuring ballast surface temperature and identifying patterns. Moreover, establishing a coarser classification of ballast fouling (categorized into three groups instead of five) significantly improves the model capability for accurate assessment of the ballast fouling conditions.
{"title":"Railway ballast fouling detection using thermal imaging: integration of LSTM and XGBoost","authors":"Mehdi Koohmishi , David P. Connolly","doi":"10.1016/j.trgeo.2025.101889","DOIUrl":"10.1016/j.trgeo.2025.101889","url":null,"abstract":"<div><div>This paper presents an artificial intelligence (AI)-based approach to automate the structural health monitoring (SHM) of railway ballast through the fusion of long short-term memory and XGBoost (LSTM-XGB) to surface temperature data derived from infrared thermal images. In this context, machine learning models are trained using remotely acquired surface temperature data to classify fouling index based on thermal variations within ballast aggregates captured from thermograms. The long short-term memory (LSTM) component processes sequential time-series thermal data to predict preceding values, and the XGBoost (XGB) component classifies fouled ballast conditions based on identified patterns of surface temperature variations measured via infrared thermography (IRT). The results confirm the capability of the LSTM component to capture the time-series variations of a specimen’s surface temperature in a shorter timeframe as well as the superior performance of XGBoost compared to a random forest (RF) approach, in classifying fouled ballast conditions. Therefore, the LSTM-XGB model demonstrates higher efficiency compared to the standalone XGBoost model, since the predictive nature of LSTM over time-series temperature data enables capturing shorter time window for measuring ballast surface temperature and identifying patterns. Moreover, establishing a coarser classification of ballast fouling (categorized into three groups instead of five) significantly improves the model capability for accurate assessment of the ballast fouling conditions.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"59 ","pages":"Article 101889"},"PeriodicalIF":5.5,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146162176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1016/j.trgeo.2025.101876
Atul Anantheswar , Sebastian Ullmann , Ines Wollny , Sebastian Skatulla , Ivo Herle , Michael Kaliske
Recent research has shown that an Arbitrary Lagrangian Eulerian (ALE) formulation can be leveraged to improve the efficiency of simulating structures subjected to moving loads, such as pavements. However, when modeling pavements, subsoil characteristics are not given much importance recently, and the subsoil is often modeled by simple linear elasticity. In this work, a hypoplastic material model capable of accurately describing the behavior of cohesionless soils, is used to model the subsoil response. Additionally, the calibration of the hypoplastic model to obtain material parameters is described. Further, the logarithmic strain approach to extend this model to finite deformations is detailed, and the incorporation of this material model into a dynamic ALE formulation is explained. Finally, the results of a transient simulation of the pavement response, when subjected to a moving load, are provided.
{"title":"Incorporation of a hypoplastic material model for sandy soils into a dynamic ALE formulation suitable for structures subjected to moving loads","authors":"Atul Anantheswar , Sebastian Ullmann , Ines Wollny , Sebastian Skatulla , Ivo Herle , Michael Kaliske","doi":"10.1016/j.trgeo.2025.101876","DOIUrl":"10.1016/j.trgeo.2025.101876","url":null,"abstract":"<div><div>Recent research has shown that an Arbitrary Lagrangian Eulerian (ALE) formulation can be leveraged to improve the efficiency of simulating structures subjected to moving loads, such as pavements. However, when modeling pavements, subsoil characteristics are not given much importance recently, and the subsoil is often modeled by simple linear elasticity. In this work, a hypoplastic material model capable of accurately describing the behavior of cohesionless soils, is used to model the subsoil response. Additionally, the calibration of the hypoplastic model to obtain material parameters is described. Further, the logarithmic strain approach to extend this model to finite deformations is detailed, and the incorporation of this material model into a dynamic ALE formulation is explained. Finally, the results of a transient simulation of the pavement response, when subjected to a moving load, are provided.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"57 ","pages":"Article 101876"},"PeriodicalIF":5.5,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145926959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rack railways are increasingly adopted in mountainous transportation networks due to their ability to operate on steep gradients. The gear-rack meshing mechanism introduces additional complexity to the train-track dynamic response. During downhill braking, the combined action of longitudinal braking forces and gravity may destabilize ballast and deform the track structure. This study investigates the dynamic characteristics of ballasted track in rack railways under downhill braking using full-scale field tests and a Multi-Body Dynamics-Discrete Element Method (MBD-DEM) simulation. First, full-scale field tests were carried out on a 120 ‰ gradient rack test line. Using conventional track condition monitoring sensors together with SmartRock sensors, we measured the wheel-rail forces, the accelerations of the rack and rail, the dynamic responses of the sleepers, and the mesoscopic dynamic behavior of ballast particles during emergency braking with different initial train speeds. Subsequently, in order to evaluate the system responses under different gradient levels and a wider range of operating conditions, and to examine in more detail the mesoscopic mechanical behavior within the ballast bed, an MBD-DEM coupled simulation model consistent with the test line was developed. Based on this model, response surface methodology was adopted to analyze the effects of gradient, train speed and braking deceleration on the track system. Results show that downhill braking induces significant axle load redistribution and longitudinal force imbalance. Higher gradients and braking loads exacerbate ballast instability. Response surface analysis indicates that gradient is the dominant factor governing longitudinal sleeper displacement. When gradients exceed 240 ‰, localized ballast instability occurs. Although sleeper displacements remain within the 2 mm safety threshold under the tested conditions, higher gradients or speeds are likely to increase track deformation and structural instability risks.
{"title":"Dynamic behavior of ballasted track in rack railway under downhill braking conditions based on experimental and numerical analysis","authors":"Jiongli Wang, Chunfa Zhao, Zaigang Chen, Jun Fang, Guojun Yang, Qiyu Zhao","doi":"10.1016/j.trgeo.2025.101888","DOIUrl":"10.1016/j.trgeo.2025.101888","url":null,"abstract":"<div><div>Rack railways are increasingly adopted in mountainous transportation networks due to their ability to operate on steep gradients. The gear-rack meshing mechanism introduces additional complexity to the train-track dynamic response. During downhill braking, the combined action of longitudinal braking forces and gravity may destabilize ballast and deform the track structure. This study investigates the dynamic characteristics of ballasted track in rack railways under downhill braking using full-scale field tests and a Multi-Body Dynamics-Discrete Element Method (MBD-DEM) simulation. First, full-scale field tests were carried out on a 120 ‰ gradient rack test line. Using conventional track condition monitoring sensors together with SmartRock sensors, we measured the wheel-rail forces, the accelerations of the rack and rail, the dynamic responses of the sleepers, and the mesoscopic dynamic behavior of ballast particles during emergency braking with different initial train speeds. Subsequently, in order to evaluate the system responses under different gradient levels and a wider range of operating conditions, and to examine in more detail the mesoscopic mechanical behavior within the ballast bed, an MBD-DEM coupled simulation model consistent with the test line was developed. Based on this model, response surface methodology was adopted to analyze the effects of gradient, train speed and braking deceleration on the track system. Results show that downhill braking induces significant axle load redistribution and longitudinal force imbalance. Higher gradients and braking loads exacerbate ballast instability. Response surface analysis indicates that gradient is the dominant factor governing longitudinal sleeper displacement. When gradients exceed 240 ‰, localized ballast instability occurs. Although sleeper displacements remain within the 2 mm safety threshold under the tested conditions, higher gradients or speeds are likely to increase track deformation and structural instability risks.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"57 ","pages":"Article 101888"},"PeriodicalIF":5.5,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1016/j.trgeo.2025.101885
Chuanjun Liu, Xiong Zhang, Jenny Liu
The moisture content (MC) was a critical parameter that needed to be monitored in geomaterial compaction. Nuclear density gauges (NDGs) had been the practice in MC and density measurement for decades but had become less desirable due to cost, regulatory, and safety concerns. Meanwhile, lightweight deflectometers (LWDs), proposed as an alternative to NDGs, did not have a function of MC measurement. This study aimed to identify a rapid field moisture analyzer to work with LWDs for evaluating the compaction acceptance of unbound materials in situ. The study started with evaluating the effectiveness and practicability of two existing moisture analyzers recommended in references, including Aggrameter and Ohaus MB 120. After the limitations of these two analyzers were identified, a further improvement on the basis of Ohaus MB 120 was conducted to develop a rapid field moisture measurement unit. Validation through field tests demonstrated that the unit effectively mitigated field disturbances and accurately measured soil MCs. Furthermore, two key parameters during the measuring process (i.e., drying weight and switch-off criterion) were investigated to optimize the accuracy and efficiency of the new unit. The drying weights of soil samples (i.e., 10 g and 30 g for non-gravel and gravel soils, respectively) and a moderate switch-off criterion were recommended for the new unit.
{"title":"A rapid field moisture measurement unit for compaction acceptance of unbound materials","authors":"Chuanjun Liu, Xiong Zhang, Jenny Liu","doi":"10.1016/j.trgeo.2025.101885","DOIUrl":"10.1016/j.trgeo.2025.101885","url":null,"abstract":"<div><div>The moisture content (MC) was a critical parameter that needed to be monitored in geomaterial compaction. Nuclear density gauges (NDGs) had been the practice in MC and density measurement for decades but had become less desirable due to cost, regulatory, and safety concerns. Meanwhile, lightweight deflectometers (LWDs), proposed as an alternative to NDGs, did not have a function of MC measurement. This study aimed to identify a rapid field moisture analyzer to work with LWDs for evaluating the compaction acceptance of unbound materials in situ. The study started with evaluating the effectiveness and practicability of two existing moisture analyzers recommended in references, including Aggrameter and Ohaus MB 120. After the limitations of these two analyzers were identified, a further improvement on the basis of Ohaus MB 120 was conducted to develop a rapid field moisture measurement unit. Validation through field tests demonstrated that the unit effectively mitigated field disturbances and accurately measured soil MCs. Furthermore, two key parameters during the measuring process (i.e., drying weight and switch-off criterion) were investigated to optimize the accuracy and efficiency of the new unit. The drying weights of soil samples (i.e., 10 g and 30 g for non-gravel and gravel soils, respectively) and a moderate switch-off criterion were recommended for the new unit.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"57 ","pages":"Article 101885"},"PeriodicalIF":5.5,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1016/j.trgeo.2025.101886
Md Asfiqur Rahman , Yu Qian , Yi Wang
Railway ballast is a crucial component of rail tracks and plays a vital role in various functions, with drainage being one of the most important for maintaining the track’s operation ability. Over time, ballast degradation and accumulation of foreign materials result in fouling, which blocks the interstitial spaces and flow passage between ballasts, thereby significantly reducing drainage efficiency. To investigate the interaction between fouling and fluid flow and its effect on fine particle migration and drainage, a coupled discrete element method (DEM) and computational fluid dynamics (CFD) model capable of solving multiphase fluid flow is developed, aiming to advance the understanding of the relevant transport behavior. The discrete (particle) and the continuous (water and air) phases are resolved using a Lagrangian and a Eulerian approach, respectively. Then, the model is employed to investigate multiphase fluid flow that washes away fouled materials through the ballast aggregate for different parameters, including fouling index, fouling profile, cohesive energy density (CED) between particles, and shoulder cleaning. This parametric simulation offers comprehensive insights into the interplay between the multiphase flow and fine particles within ballast at different conditions. Moreover, the particle distribution and their migrations over time are quantitatively evaluated using the Local Fouling Index. It is evident from the analysis that particle migration greatly depends on the parameters under consideration, with the CED value being the most important factor. Additionally, the comparison of the water table height demonstrates that shoulder cleaning is an effective means of improving drainage efficiency.
{"title":"Investigation of particle migration and drainage behavior in railway ballast induced by multiphase flow using a coupled VOF-DEM approach","authors":"Md Asfiqur Rahman , Yu Qian , Yi Wang","doi":"10.1016/j.trgeo.2025.101886","DOIUrl":"10.1016/j.trgeo.2025.101886","url":null,"abstract":"<div><div>Railway ballast is a crucial component of rail tracks and plays a vital role in various functions, with drainage being one of the most important for maintaining the track’s operation ability. Over time, ballast degradation and accumulation of foreign materials result in fouling, which blocks the interstitial spaces and flow passage between ballasts, thereby significantly reducing drainage efficiency. To investigate the interaction between fouling and fluid flow and its effect on fine particle migration and drainage, a coupled discrete element method (DEM) and computational fluid dynamics (CFD) model capable of solving multiphase fluid flow is developed, aiming to advance the understanding of the relevant transport behavior. The discrete (particle) and the continuous (water and air) phases are resolved using a Lagrangian and a Eulerian approach, respectively. Then, the model is employed to investigate multiphase fluid flow that washes away fouled materials through the ballast aggregate for different parameters, including fouling index, fouling profile, cohesive energy density (CED) between particles, and shoulder cleaning. This parametric simulation offers comprehensive insights into the interplay between the multiphase flow and fine particles within ballast at different conditions. Moreover, the particle distribution and their migrations over time are quantitatively evaluated using the Local Fouling Index. It is evident from the analysis that particle migration greatly depends on the parameters under consideration, with the CED value being the most important factor. Additionally, the comparison of the water table height demonstrates that shoulder cleaning is an effective means of improving drainage efficiency.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"57 ","pages":"Article 101886"},"PeriodicalIF":5.5,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1016/j.trgeo.2025.101887
Jianhong Jiang , Sikang Tu , Jianguang Feng
Understanding the mechanical response of silt–clay transitional soils is increasingly important for underground transportation infrastructure, where complex stress paths and one-dimensional (K0) consolidation histories are common. However, most existing studies rely on isotropic consolidation, leaving the effects of K0 consolidation on transitional behavior insufficiently understood. This study presents a systematic series of undrained triaxial tests on reconstituted silty clay consolidated under isotropic and K0 conditions across a range of overconsolidation ratios (OCRs). The results show that phase transformation—a hallmark of transitional soil behavior—appears only in isotropically consolidated specimens at low OCRs, whereas it does not occur in K0-consolidated specimens tested under comparable OCRs. K0-consolidated specimens exhibit a counter-intuitive non-monotonic relationship between void ratio and mean effective stress at the end of shearing, reflecting persistent anisotropic structural effects consistent with anisotropic critical state theory. While K0 consolidation produces more complex stress–strain responses, the stress-ratio evolution remains broadly comparable to isotropically consolidated cases. Overall, the findings demonstrate that consolidation history critically governs the undrained behavior of silt–clay transitional soils and underscore the importance of incorporating realistic K0 consolidation conditions in laboratory characterization and geotechnical design for transportation applications.
{"title":"Influence of consolidation history on the transitional behavior of silty clay","authors":"Jianhong Jiang , Sikang Tu , Jianguang Feng","doi":"10.1016/j.trgeo.2025.101887","DOIUrl":"10.1016/j.trgeo.2025.101887","url":null,"abstract":"<div><div>Understanding the mechanical response of silt–clay transitional soils is increasingly important for underground transportation infrastructure, where complex stress paths and one-dimensional (K<sub>0</sub>) consolidation histories are common. However, most existing studies rely on isotropic consolidation, leaving the effects of K<sub>0</sub> consolidation on transitional behavior insufficiently understood. This study presents a systematic series of undrained triaxial tests on reconstituted silty clay consolidated under isotropic and K<sub>0</sub> conditions across a range of overconsolidation ratios (OCRs). The results show that phase transformation—a hallmark of transitional soil behavior—appears only in isotropically consolidated specimens at low OCRs, whereas it does not occur in K<sub>0</sub>-consolidated specimens tested under comparable OCRs. K<sub>0</sub>-consolidated specimens exhibit a counter-intuitive non-monotonic relationship between void ratio and mean effective stress at the end of shearing, reflecting persistent anisotropic structural effects consistent with anisotropic critical state theory. While K<sub>0</sub> consolidation produces more complex stress–strain responses, the stress-ratio evolution remains broadly comparable to isotropically consolidated cases. Overall, the findings demonstrate that consolidation history critically governs the undrained behavior of silt–clay transitional soils and underscore the importance of incorporating realistic K<sub>0</sub> consolidation conditions in laboratory characterization and geotechnical design for transportation applications.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"57 ","pages":"Article 101887"},"PeriodicalIF":5.5,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1016/j.trgeo.2025.101884
Ayazhan Bazarbekova , Yong-Rak Kim , Dallas Little , Jong Suk Jung , Yong-Boo Park
Expansive clays pose significant challenges in civil engineering due to their high shrink–swell potential, which can compromise stability and cause structural damage. This study adopts a phased approach to develop effective stabilizer blends by integrating gypsum into industrial by-products, such as fly ash and slag, to enhance the durability of smectite-rich clay. In the first phase, gypsum-free blends were formulated to investigate the combined effects of additives and determine the optimal stabilizer content. The best-performing mix was then tested in a field implementation phase to validate its performance under real-world conditions. In the later phase, gypsum was incorporated and evaluated under wetting–drying (W–D) cycles to simulate environmental moisture fluctuations. The gypsum content was limited to avoid excessive sulfate reactions, particularly ettringite formation. An integrated framework, including strength testing, chemical assessment, and mineralogical analysis, was applied to unmodified, gypsum-modified, and gypsum-modified samples subjected to W–D cycling. Chemical treatment significantly improved strength, increasing the unconfined compressive strength (0.31 MPa) of untreated soil by about 6–8 times, with Class C fly ash and slag providing the best performance. The gypsum-modified blend retained ∼54 % of its initial strength after five W–D cycles, demonstrating improved resistance to moisture-induced deterioration. Mineralogical analyses indicated transformations such as smectite modification, ettringite formation, and calcite precipitation. These findings underscore gypsum’s role in enhancing the performance of expansive soils with moisture fluctuations and contribute to advancing stabilization strategies for resilient transportation infrastructure.
{"title":"Laboratory and field assessment of gypsum-modified aluminosilicate blends for expansive clay stabilization","authors":"Ayazhan Bazarbekova , Yong-Rak Kim , Dallas Little , Jong Suk Jung , Yong-Boo Park","doi":"10.1016/j.trgeo.2025.101884","DOIUrl":"10.1016/j.trgeo.2025.101884","url":null,"abstract":"<div><div>Expansive clays pose significant challenges in civil engineering due to their high shrink–swell potential, which can compromise stability and cause structural damage. This study adopts a phased approach to develop effective stabilizer blends by integrating gypsum into industrial by-products, such as fly ash and slag, to enhance the durability of smectite-rich clay. In the first phase, gypsum-free blends were formulated to investigate the combined effects of additives and determine the optimal stabilizer content. The best-performing mix was then tested in a field implementation phase to validate its performance under real-world conditions. In the later phase, gypsum was incorporated and evaluated under wetting–drying (W–D) cycles to simulate environmental moisture fluctuations. The gypsum content was limited to avoid excessive sulfate reactions, particularly ettringite formation. An integrated framework, including strength testing, chemical assessment, and mineralogical analysis, was applied to unmodified, gypsum-modified, and gypsum-modified samples subjected to W–D cycling. Chemical treatment significantly improved strength, increasing the unconfined compressive strength (0.31 MPa) of untreated soil by about 6–8 times, with Class C fly ash and slag providing the best performance. The gypsum-modified blend retained ∼54 % of its initial strength after five W–D cycles, demonstrating improved resistance to moisture-induced deterioration. Mineralogical analyses indicated transformations such as smectite modification, ettringite formation, and calcite precipitation. These findings underscore gypsum’s role in enhancing the performance of expansive soils with moisture fluctuations and contribute to advancing stabilization strategies for resilient transportation infrastructure.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"57 ","pages":"Article 101884"},"PeriodicalIF":5.5,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号