Pub Date : 2026-03-01Epub Date: 2026-02-04DOI: 10.1016/j.trgeo.2026.101920
Yu Zhang , Changke Sang , Sheng Shi , Hui Zhang
The station platforms of the Qinghai–Xizang Railway are subject to persistent frost heave due to severe cold, large temperature fluctuations, and groundwater-rich conditions. To investigate the governing mechanisms and evaluate mitigation strategies, a one-dimensional thermal–hydraulic coupled freezing system was developed, and staged freezing tests with unconfined water replenishment were conducted on silty clay from Chumar River Station. Three mitigation measures—conventional geomembrane, composite geomembrane, and a 20 mm gravel isolation layer—were assessed. The results show that frost heave is primarily driven by the migration of unfrozen water toward the freezing front, where a moisture-enriched zone forms and segregated ice lenses develop. After freezing, the water content below the freezing front becomes nearly uniform, while the upper soil exhibits a unimodal increase due to moisture redistribution. Among the mitigation measures, the composite geomembrane is the most effective, reducing the frost heave ratio by 5.81%, followed by the conventional geomembrane (5.21%) and the gravel isolation layer (2.12%). Numerical models successfully reproduce the observed variations in temperature, moisture, and displacement. These findings provide practical guidance for mitigating frost heave at station platforms along the Qinghai–Xizang Railway.
{"title":"Frost Heave Characteristics of Qinghai–Xizang Silty Clay: Experimental and Numerical Modeling","authors":"Yu Zhang , Changke Sang , Sheng Shi , Hui Zhang","doi":"10.1016/j.trgeo.2026.101920","DOIUrl":"10.1016/j.trgeo.2026.101920","url":null,"abstract":"<div><div>The station platforms of the Qinghai–Xizang Railway are subject to persistent frost heave due to severe cold, large temperature fluctuations, and groundwater-rich conditions. To investigate the governing mechanisms and evaluate mitigation strategies, a one-dimensional thermal–hydraulic coupled freezing system was developed, and staged freezing tests with unconfined water replenishment were conducted on silty clay from Chumar River Station. Three mitigation measures—conventional geomembrane, composite geomembrane, and a 20 mm gravel isolation layer—were assessed. The results show that frost heave is primarily driven by the migration of unfrozen water toward the freezing front, where a moisture-enriched zone forms and segregated ice lenses develop. After freezing, the water content below the freezing front becomes nearly uniform, while the upper soil exhibits a unimodal increase due to moisture redistribution. Among the mitigation measures, the composite geomembrane is the most effective, reducing the frost heave ratio by 5.81%, followed by the conventional geomembrane (5.21%) and the gravel isolation layer (2.12%). Numerical models successfully reproduce the observed variations in temperature, moisture, and displacement. These findings provide practical guidance for mitigating frost heave at station platforms along the Qinghai–Xizang Railway.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101920"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190530","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 : 2026-03-01Epub Date: 2026-01-27DOI: 10.1016/j.trgeo.2026.101918
Boyang Xia , Meng Wei , Gang Zheng , Haizuo Zhou
Optimizing column arrangements is a complex task in column-supported embankment design, because it requires balancing multiple performance objectives and cost. Consequently, a comprehensive optimization framework is essential for identifying the optimal column configuration during the design process. This study developed a multi-objective optimization approach for designing column arrangements to support embankments constructed on soft ground. The proposed approach integrates both sequential surrogate methods and adaptive evolutionary algorithms to predict and optimize column arrangements in column-supported embankment design. The proposed optimization framework was applied to a practical embankment project at the Xingxing interchange section. Four objective functions were defined using the global stability (Fs), maximum total settlement and differential settlement of the embankment surface (St, Sd), and cost of the concrete columns (C). Evaluation of the results confirmed the excellent prediction accuracy of the proposed method. Besides, compared with the original design, the optimal design achieved a 17% increase in Fs, and 4%, 0.39%, and 10% reduction in St, Sd, and C, respectively. The proposed optimization framework and its outcomes offer a practical strategy for optimizing investments in transportation embankment projects.
{"title":"Multi-objective optimization design based on surrogate modelling for concrete column-supported embankment on soft ground","authors":"Boyang Xia , Meng Wei , Gang Zheng , Haizuo Zhou","doi":"10.1016/j.trgeo.2026.101918","DOIUrl":"10.1016/j.trgeo.2026.101918","url":null,"abstract":"<div><div>Optimizing column arrangements is a complex task in column-supported embankment design, because it requires balancing multiple performance objectives and cost. Consequently, a comprehensive optimization framework is essential for identifying the optimal column configuration during the design process. This study developed a multi-objective optimization approach for designing column arrangements to support embankments constructed on soft ground. The proposed approach integrates both sequential surrogate methods and adaptive evolutionary algorithms to predict and optimize column arrangements in column-supported embankment design. The proposed optimization framework was applied to a practical embankment project at the Xingxing interchange section. Four objective functions were defined using the global stability (<em>F</em><sub>s</sub>), maximum total settlement and differential settlement of the embankment surface (<em>S</em><sub>t</sub>, <em>S</em><sub>d</sub>), and cost of the concrete columns (<em>C</em>). Evaluation of the results confirmed the excellent prediction accuracy of the proposed method. Besides, compared with the original design, the optimal design achieved a 17% increase in <em>F</em><sub>s</sub>, and 4%, 0.39%, and 10% reduction in <em>S</em><sub>t</sub>, <em>S</em><sub>d</sub>, and <em>C</em>, respectively. The proposed optimization framework and its outcomes offer a practical strategy for optimizing investments in transportation embankment projects.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101918"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080420","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 : 2026-03-01Epub Date: 2026-02-07DOI: 10.1016/j.trgeo.2026.101943
Zeqi Chen , Ying Gao , Junyao Tang , Yingsong Li , Zhuoran Li , Ziyue Zhou , Xiaoming Huang , Huan Wang , Yanshun Jia , Shaoquan Wang
Shaking table tests and finite element (FE) methods are widely used and complementary approaches for embankment seismic analysis. Their boundary treatments fundamentally influence the dynamic responses. This study optimized the flexible boundary layer of scaled shaking table models and developed a viscoelastic boundary implementation for three-dimensional FE embankment models. Comparative analyses of the seismic responses under the two boundary conditions were conducted to evaluate their influence on the dynamic behavior of embankments. A dynamic compression test was conducted on flexible materials, confirming ethylene vinyl acetate (EVA) copolymer suitable based on energy dissipation stability and residual height ratio. A seven-term Prony series viscoelastic model of EVA was developed for FE simulations of boundary effects. The simulation results indicate that a 3 cm flexible layer effectively reduces boundary effects. Subsequently, a FE model of embankment with viscoelastic boundaries was developed to simulate realistic seismic wave propagation. Comparison results indicate that FE seismic input calibration is necessary to match base peak accelerations in both methods. Subsequent analyses revealed that, in numerical simulations, acceleration amplification factors remain stable at low intensities and decrease with strain, whereas in shaking table tests, they initially increase due to wave reflections before declining. Moreover, decreasing the angle between seismic direction and the subgrade vertical axis reduces slope amplification factors, with the effect amplified in shaking table tests. These findings provide practical guidance for designing flexible boundaries in shaking table tests and implementing viscoelastic boundaries in numerical simulations, while highlighting differences in the dynamic responses of the two methods.
{"title":"A framework for mitigating boundary effects in transportation embankment seismic analysis: shaking table tests and numerical simulations","authors":"Zeqi Chen , Ying Gao , Junyao Tang , Yingsong Li , Zhuoran Li , Ziyue Zhou , Xiaoming Huang , Huan Wang , Yanshun Jia , Shaoquan Wang","doi":"10.1016/j.trgeo.2026.101943","DOIUrl":"10.1016/j.trgeo.2026.101943","url":null,"abstract":"<div><div>Shaking table tests and finite element (FE) methods are widely used and complementary approaches for embankment seismic analysis. Their boundary treatments fundamentally influence the dynamic responses. This study optimized the flexible boundary layer of scaled shaking table models and developed a viscoelastic boundary implementation for three-dimensional FE embankment models. Comparative analyses of the seismic responses under the two boundary conditions were conducted to evaluate their influence on the dynamic behavior of embankments. A dynamic compression test was conducted on flexible materials, confirming ethylene vinyl acetate (EVA) copolymer suitable based on energy dissipation stability and residual height ratio. A seven-term Prony series viscoelastic model of EVA was developed for FE simulations of boundary effects. The simulation results indicate that a 3 cm flexible layer effectively reduces boundary effects. Subsequently, a FE model of embankment with viscoelastic boundaries was developed to simulate realistic seismic wave propagation. Comparison results indicate that FE seismic input calibration is necessary to match base peak accelerations in both methods. Subsequent analyses revealed that, in numerical simulations, acceleration amplification factors remain stable at low intensities and decrease with strain, whereas in shaking table tests, they initially increase due to wave reflections before declining. Moreover, decreasing the angle between seismic direction and the subgrade vertical axis reduces slope amplification factors, with the effect amplified in shaking table tests. These findings provide practical guidance for designing flexible boundaries in shaking table tests and implementing viscoelastic boundaries in numerical simulations, while highlighting differences in the dynamic responses of the two methods.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101943"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190527","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 : 2026-03-01Epub Date: 2026-01-23DOI: 10.1016/j.trgeo.2026.101914
Ke Wang , Tianxiao Tang , Shanzhen Li , Shuang Tian , Lianzhen Zhang , Shuang Liu , Xianzhang Ling
Frost heave and thaw settlement in frozen high-speed railway subgrades are governed by coupled water and heat migration in the soil, and may be further intensified by traffic-induced vibration. However, the underlying hydro-mechanical processes in frozen, partially saturated subgrades remain poorly quantified, especially when dynamic loading acts concurrently with freeze–thaw cycles. In this study, a custom one-dimensional freezing apparatus with superimposed cyclic loading was used to investigate water migration in unsaturated frozen soils representative of high-speed railway subgrades. A test matrix of ten soil samples was designed, varying freezing temperature (−5℃ to −20℃), soil compaction (90% vs 95% relative), initial moisture content (10%, 14%, 18%), and soil type (silty clay versus gravelly fill). Real-time measurements of temperature, unfrozen water content, water replenishment, and pore water pressure were obtained throughout the experiments. Substantial upward water migration into the freezing zone was observed in all tests. Lower freezing temperatures markedly increased both the volume and rate of water replenishment, whereas compaction (within 90–95%) had little influence. Soil type and layering controlled the magnitude and timing of upward flux: silty clay induced greater and faster water uptake than Group B fill, and layered profiles showed distinct stagewise behavior. Notably, a vibration-induced piston suction mechanism was identified: cyclic vehicular loading acting on a frozen, low-permeability upper layer generated excess pore water pressure in the underlying unfrozen zone, establishing a sustained hydraulic gradient that pumped unfrozen water toward the freezing front. This mechanism is different from mud pumping and pot cover effects. A unified conceptual framework is proposed that links matric suction, cryogenic suction, and vibration-induced piston suction, delineates their respective domains of dominance, and provides physically based guidance for modeling water migration in frozen high-speed railway subgrades and related cold region porous media.
冻土高速铁路路基的冻胀和融沉主要受土壤中水热耦合迁移的控制，并可能在交通振动的作用下进一步加剧。然而，在冻结的、部分饱和的路基中，潜在的水力学过程仍然很难量化，特别是当动力加载与冻融循环同时发生时。本文采用自定义的一维叠加循环加载冻结装置，对具有代表性的高速铁路路基非饱和冻土的水分迁移进行了研究。设计了10个土壤样品的测试基质，不同的冻结温度（- 5℃至- 20℃），土壤压实度（90% vs 95%相对），初始含水量（10%,14%,18%）和土壤类型（粉质粘土与砾石填充）。在整个实验过程中，实时测量温度、未冻水含量、补水和孔隙水压力。在所有试验中都观察到大量向上的水向冻结区迁移。较低的冻结温度显著提高了补水量和补水量，而压实（90-95%）对补水量影响不大。土壤类型和分层控制了上升通量的大小和时间：粉质粘土比B组填土吸收水分更多、更快，分层剖面表现出明显的阶段性特征。值得注意的是，研究人员确定了一种振动诱导的活塞吸力机制：循环车辆荷载作用于冻结的低渗透上层，在下层未冻结区产生超额孔隙水压力，建立持续的水力梯度，将未冻结水泵向冻结前沿。这种机理不同于泥浆泵送和罐盖效应。提出了一个统一的概念框架，将基质吸力、低温吸力和振动诱导活塞吸力联系起来，划定了各自的优势领域，为高速铁路冻土路基及相关寒区多孔介质的水迁移建模提供了基于物理的指导。
{"title":"Water migration in frozen high-speed railway subgrades under traffic vibration: Piston suction versus mud pumping and pot cover effect","authors":"Ke Wang , Tianxiao Tang , Shanzhen Li , Shuang Tian , Lianzhen Zhang , Shuang Liu , Xianzhang Ling","doi":"10.1016/j.trgeo.2026.101914","DOIUrl":"10.1016/j.trgeo.2026.101914","url":null,"abstract":"<div><div>Frost heave and thaw settlement in frozen high-speed railway subgrades are governed by coupled water and heat migration in the soil, and may be further intensified by traffic-induced vibration. However, the underlying hydro-mechanical processes in frozen, partially saturated subgrades remain poorly quantified, especially when dynamic loading acts concurrently with freeze–thaw cycles. In this study, a custom one-dimensional freezing apparatus with superimposed cyclic loading was used to investigate water migration in unsaturated frozen soils representative of high-speed railway subgrades. A test matrix of ten soil samples was designed, varying freezing temperature (−5℃ to −20℃), soil compaction (90% vs 95% relative), initial moisture content (10%, 14%, 18%), and soil type (silty clay versus gravelly fill). Real-time measurements of temperature, unfrozen water content, water replenishment, and pore water pressure were obtained throughout the experiments. Substantial upward water migration into the freezing zone was observed in all tests. Lower freezing temperatures markedly increased both the volume and rate of water replenishment, whereas compaction (within 90–95%) had little influence. Soil type and layering controlled the magnitude and timing of upward flux: silty clay induced greater and faster water uptake than Group B fill, and layered profiles showed distinct stagewise behavior. Notably, a vibration-induced piston suction mechanism was identified: cyclic vehicular loading acting on a frozen, low-permeability upper layer generated excess pore water pressure in the underlying unfrozen zone, establishing a sustained hydraulic gradient that pumped unfrozen water toward the freezing front. This mechanism is different from mud pumping and pot cover effects. A unified conceptual framework is proposed that links matric suction, cryogenic suction, and vibration-induced piston suction, delineates their respective domains of dominance, and provides physically based guidance for modeling water migration in frozen high-speed railway subgrades and related cold region porous media.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101914"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189909","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 : 2026-03-01Epub Date: 2026-01-26DOI: 10.1016/j.trgeo.2026.101923
Liyuan Liu , Jie Deng , Huailei Cheng , Kaili Hao , Lijun Sun , Miomir Miljković , Chen Cui
Resonant rubblization technique has been widely used to for the rehabilitation of concrete pavements with asphalt overlay, due to its advantage in reducing reflective cracking of overlay layer. Conventional studies mainly focus on investigating mechanical responses of rubblized concrete pavement system under traffic loads, while this study systematically investigates the pavement’s thermal responses when subjected to environmental temperature variations. Finite element (FE) models were developed for both resonant rubblized and conventional (unrubblized) concrete pavements with asphalt overlay. These models were validated against field-measured data, with the correlation coefficient between the simulated and measured data reaching 0.827. On the basis of the validated models, a comparative analysis was conducted to examine the thermal responses of the two pavement systems under diverse climatic conditions, including daily temperature variations, abrupt temperature changes, and constant temperature gradients. The results demonstrate that the tensile stresses and strains in the asphalt overlay of rubblized pavements are substantially lower than those in conventional pavements. The reduction in stress/strain is most pronounced at the bottom of asphalt overlay adjacent to the original cement slab, where the maximum tensile stress is reduced to approximately 35% of that observed in the unrubblized pavement, thereby effectively suppressing the initiation and propagation of reflective cracking. Furthermore, cold regions—characterized by larger daily temperature ranges—exhibit more pronounced temperature gradients within the pavement, resulting in more severe fluctuations in thermal responses compared with hot regions. For abruptly temperature-changing conditions, the rubblized pavement also exhibits a more uniform stress distribution and superior structural stability than conventional pavement. Besides, the thermal displacement of the rubblized pavement is only 20% of that of the concrete slabs in conventional pavement, revealing that the rubblization is beneficial in mitigating thermal-induced displacement of original concrete slab and thus reducing the reflective cracking in asphalt overlay. Findings of this research is expected to guide the analysis and design of rubblized concrete pavement system across diverse climatic conditions.
{"title":"Analysis of thermal–mechanical responses of resonant rubblized concrete pavement system with asphalt overlay under diverse climatic conditions","authors":"Liyuan Liu , Jie Deng , Huailei Cheng , Kaili Hao , Lijun Sun , Miomir Miljković , Chen Cui","doi":"10.1016/j.trgeo.2026.101923","DOIUrl":"10.1016/j.trgeo.2026.101923","url":null,"abstract":"<div><div>Resonant rubblization technique has been widely used to for the rehabilitation of concrete pavements with asphalt overlay, due to its advantage in reducing reflective cracking of overlay layer. Conventional studies mainly focus on investigating mechanical responses of rubblized concrete pavement system under traffic loads, while this study systematically investigates the pavement’s thermal responses when subjected to environmental temperature variations. Finite element (FE) models were developed for both resonant rubblized and conventional (unrubblized) concrete pavements with asphalt overlay. These models were validated against field-measured data, with the correlation coefficient between the simulated and measured data reaching 0.827. On the basis of the validated models, a comparative analysis was conducted to examine the thermal responses of the two pavement systems under diverse climatic conditions, including daily temperature variations, abrupt temperature changes, and constant temperature gradients. The results demonstrate that the tensile stresses and strains in the asphalt overlay of rubblized pavements are substantially lower than those in conventional pavements. The reduction in stress/strain is most pronounced at the bottom of asphalt overlay adjacent to the original cement slab, where the maximum tensile stress is reduced to approximately 35% of that observed in the unrubblized pavement, thereby effectively suppressing the initiation and propagation of reflective cracking. Furthermore, cold regions—characterized by larger daily temperature ranges—exhibit more pronounced temperature gradients within the pavement, resulting in more severe fluctuations in thermal responses compared with hot regions. For abruptly temperature-changing conditions, the rubblized pavement also exhibits a more uniform stress distribution and superior structural stability than conventional pavement. Besides, the thermal displacement of the rubblized pavement is only 20% of that of the concrete slabs in conventional pavement, revealing that the rubblization is beneficial in mitigating thermal-induced displacement of original concrete slab and thus reducing the reflective cracking in asphalt overlay. Findings of this research is expected to guide the analysis and design of rubblized concrete pavement system across diverse climatic conditions.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101923"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080495","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 : 2026-03-01Epub Date: 2026-01-19DOI: 10.1016/j.trgeo.2026.101903
O. Guerrero-Bustamante , A. Guillen , F. Moreno-Navarro , M.C. Rubio-Gámez , M. Sol-Sánchez
This research presents an experimental evaluation of diverse bituminous materials for high-performance sub-ballast in railway tracks, produced through various manufacturing technologies including hot, warm, and cold mix asphalt, focusing on mixtures with 100% reclaimed asphalt pavement (RAP). The research addresses a strategic line toward more sustainable materials for railway tracks, while covering key gaps in understanding the mechanical and vibrational behavior of bituminous sub-ballast specifically used in railway applications. A comprehensive testing program was designed to evaluate crucial characteristics of these materials validating their functionality and suitability, like indirect tensile strength and stiffness, permanent deformation, vibration-damping capacity, permeability, and bearing capacity. Among the findings, RAP-based hot and warm mix asphalt (HMA-R and WMA-R) showed superior mechanical performance, with increases of up to 73% in strength and 84% in stiffness compared to conventional HMA. However, HMA-R exhibited increased brittleness due to excessive stiffening. In contrast, the temperature reduction in WMA-R helped restore mixture ductility and toughness, offering a more balanced behavior despite its high RAP content. In terms of vibration mitigation, WMA-R achieved a 31% reduction in acceleration and maintained a damping performance comparable to conventional granular references. Bituminous RAP mixtures also exhibited appropriate subgrade protection, with up to 70% lower infiltration rates, water sensitivity ratios exceeding 90%, and excellent bearing capacity. To facilitate performance comparison, a multi-criteria framework was developed, integrating weighted improvement indicators across four behavioral categories. WMA-R emerged as the most technically balanced solution, offering a favorable compromise between structural performance and vibration control for modern, sustainable railway infrastructures.
{"title":"Comparative evaluation of high-RAP bituminous and granular sub-ballast mixtures for railway infrastructure","authors":"O. Guerrero-Bustamante , A. Guillen , F. Moreno-Navarro , M.C. Rubio-Gámez , M. Sol-Sánchez","doi":"10.1016/j.trgeo.2026.101903","DOIUrl":"10.1016/j.trgeo.2026.101903","url":null,"abstract":"<div><div>This research presents an experimental evaluation of diverse bituminous materials for high-performance sub-ballast in railway tracks, produced through various manufacturing technologies including hot, warm, and cold mix asphalt, focusing on mixtures with 100% reclaimed asphalt pavement (RAP). The research addresses a strategic line toward more sustainable materials for railway tracks, while covering key gaps in understanding the mechanical and vibrational behavior of bituminous sub-ballast specifically used in railway applications. A comprehensive testing program was designed to evaluate crucial characteristics of these materials validating their functionality and suitability, like indirect tensile strength and stiffness, permanent deformation, vibration-damping capacity, permeability, and bearing capacity. Among the findings, RAP-based hot and warm mix asphalt (HMA-R and WMA-R) showed superior mechanical performance, with increases of up to 73% in strength and 84% in stiffness compared to conventional HMA. However, HMA-R exhibited increased brittleness due to excessive stiffening. In contrast, the temperature reduction in WMA-R helped restore mixture ductility and toughness, offering a more balanced behavior despite its high RAP content. In terms of vibration mitigation, WMA-R achieved a 31% reduction in acceleration and maintained a damping performance comparable to conventional granular references. Bituminous RAP mixtures also exhibited appropriate subgrade protection, with up to 70% lower infiltration rates, water sensitivity ratios exceeding 90%, and excellent bearing capacity. To facilitate performance comparison, a multi-criteria framework was developed, integrating weighted improvement indicators across four behavioral categories. WMA-R emerged as the most technically balanced solution, offering a favorable compromise between structural performance and vibration control for modern, sustainable railway infrastructures.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101903"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145996325","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 : 2026-03-01Epub Date: 2026-01-19DOI: 10.1016/j.trgeo.2026.101906
Junchen Zhang , Liufeng Su , Wang Wu , Yanliang Du , Qixiang Yan , Yu Zhao
The performance status of circular Tunnel Boring Machine tunnels predominantly relies on qualitative evaluations using limited indicators, which fail to fully utilize high-volume field data from modern detection technologies, resulting in suboptimal specificity and reliability of the analysis outcomes. This study proposed a new assessment method for safety status of circular tunnels considering the integration of analytical models with displacement data. The assessment method fully considered the multisource data including the geological information, tunnel dimensions, actual lining displacements, lining reinforcement, and nonlinear constitutive relationships of the lining materials. The internal forces and stresses of the circular tunnel were calculated by the analytical models. Numerical modeling validation confirmed the model’s reliability. The applicable scope of the assessment method was clarified through the parameter sensitivity analyses. A safety evaluation index and its classification derived from the assessment method were subsequently established. The research findings reveal that the correlation coefficients (between test values and analytical values) of lining displacement, bending moment and axial force are more than 98 %, 97 % and 86 % respectively under the shallow and deep buried tunnel scenarios, which verified the reliability of the integration between analytical models and displacement data. The mechanical behaviors of a circular tunnel are influenced by factors such as the geological types, tunnel dimensions, lining displacements, lining reinforcement and lining material types. The ratio of lining stress to its yield strength (stress-strength ratio) ultimately determines the safety of the tunnel. It is worth mentioning that the safety state of the lining ring cannot be identified separately by the ovality of displacement, which should be determined jointly by the major and minor axes of the elliptical deformation. According to parameter sensitivity analysis, the order of sensitivity influence on the stress-strength ratio is: structural displacement > lining thickness > tunnel diameter > lining strength > soil lateral pressure coefficients. The assessment method synergizes with detection technology advancements, which provides theoretical foundations for predicting the mechanical performance of service tunnels.
{"title":"A new assessment method for safety status of circular tunnels considering the integration of analytical models with displacement data","authors":"Junchen Zhang , Liufeng Su , Wang Wu , Yanliang Du , Qixiang Yan , Yu Zhao","doi":"10.1016/j.trgeo.2026.101906","DOIUrl":"10.1016/j.trgeo.2026.101906","url":null,"abstract":"<div><div>The performance status of circular Tunnel Boring Machine tunnels predominantly relies on qualitative evaluations using limited indicators, which fail to fully utilize high-volume field data from modern detection technologies, resulting in suboptimal specificity and reliability of the analysis outcomes. This study proposed a new assessment method for safety status of circular tunnels considering the integration of analytical models with displacement data. The assessment method fully considered the multisource data including the geological information, tunnel dimensions, actual lining displacements, lining reinforcement, and nonlinear constitutive relationships of the lining materials. The internal forces and stresses of the circular tunnel were calculated by the analytical models. Numerical modeling validation confirmed the model’s reliability. The applicable scope of the assessment method was clarified through the parameter sensitivity analyses. A safety evaluation index and its classification derived from the assessment method were subsequently established. The research findings reveal that the correlation coefficients (between test values and analytical values) of lining displacement, bending moment and axial force are more than 98 %, 97 % and 86 % respectively under the shallow and deep buried tunnel scenarios, which verified the reliability of the integration between analytical models and displacement data. The mechanical behaviors of a circular tunnel are influenced by factors such as the geological types, tunnel dimensions, lining displacements, lining reinforcement and lining material types. The ratio of lining stress to its yield strength (stress-strength ratio) ultimately determines the safety of the tunnel. It is worth mentioning that the safety state of the lining ring cannot be identified separately by the ovality of displacement, which should be determined jointly by the major and minor axes of the elliptical deformation. According to parameter sensitivity analysis, the order of sensitivity influence on the stress-strength ratio is: structural displacement > lining thickness > tunnel diameter > lining strength > soil lateral pressure coefficients. The assessment method synergizes with detection technology advancements, which provides theoretical foundations for predicting the mechanical performance of service tunnels.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101906"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039521","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 : 2026-03-01Epub Date: 2026-02-06DOI: 10.1016/j.trgeo.2026.101922
E. Ríos-Otero , E. Aldao , L.M. Fernández-Pardo , G. Fontenla-Carrera , F. Veiga-López , H. González-Jorge
High-speed railways are increasingly preferred for medium-distance travel, thanks to their efficiency and convenience. However, the growing frequency of services accelerates infrastructure wear, raising inspection and maintenance demands. To address this, autonomous inspection solutions based on LiDAR (Light Detection and Ranging) systems and onboard cameras have recently been proposed, but their testing and deployment remain challenging due to regulatory constraints and the difficulty of accessing representative railway environments. This work presents a LiDAR digital twin that realistically replicates sensor behaviour in real railway track environments. The simulator incorporates CAD (Computer-Aided Design) models of the track vehicle and sensor installation, enabling the assessment of installation-related limitations and sensor field-of-view occlusions. Two commercial sensors, the Livox Avia and Livox HAP, were metrologically calibrated using experimental data acquired on a real railway track. Good agreement between simulated and experimental data was observed, with deviations of only 2 points/cm in point density and centimetre-level differences in reconstructed ballast geometry. The digital twin was subsequently used to assess the suitability of this technology for ballast geometry measurement at different travel speeds, showing centimetre-order errors for both sensors at speeds of up to 120 km/h.
{"title":"A digital-twin LiDAR simulator for performance assessment of railway ballast geometry inspections","authors":"E. Ríos-Otero , E. Aldao , L.M. Fernández-Pardo , G. Fontenla-Carrera , F. Veiga-López , H. González-Jorge","doi":"10.1016/j.trgeo.2026.101922","DOIUrl":"10.1016/j.trgeo.2026.101922","url":null,"abstract":"<div><div>High-speed railways are increasingly preferred for medium-distance travel, thanks to their efficiency and convenience. However, the growing frequency of services accelerates infrastructure wear, raising inspection and maintenance demands. To address this, autonomous inspection solutions based on LiDAR (Light Detection and Ranging) systems and onboard cameras have recently been proposed, but their testing and deployment remain challenging due to regulatory constraints and the difficulty of accessing representative railway environments. This work presents a LiDAR digital twin that realistically replicates sensor behaviour in real railway track environments. The simulator incorporates CAD (Computer-Aided Design) models of the track vehicle and sensor installation, enabling the assessment of installation-related limitations and sensor field-of-view occlusions. Two commercial sensors, the Livox Avia and Livox HAP, were metrologically calibrated using experimental data acquired on a real railway track. Good agreement between simulated and experimental data was observed, with deviations of only <span><math><mo>≃</mo></math></span>2 points/cm<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> in point density and centimetre-level differences in reconstructed ballast geometry. The digital twin was subsequently used to assess the suitability of this technology for ballast geometry measurement at different travel speeds, showing centimetre-order errors for both sensors at speeds of up to 120 km/h.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101922"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190531","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}
The process of forced convection heat transfer at the atmosphere-soil interface modifies thermal boundary conditions, thereby influencing internal thermo-hydro-mechanical (THM) responses and triggering progressive slope instability. While existing studies on freeze–thaw-induced slope deterioration either employ natural convection boundary or conductive heat transfer boundary to investigate soil responses, yet the effects of forced convection on slope degradation processes have rarely been considered. To address this gap, a novel freeze–thaw cycling apparatus was developed to simulate convective heat transfer boundaries at the atmosphere-soil interface. Physical model tests were conducted under two distinct flow fields characterized by different convection directions: upper-blowing (UB) and lower-blowing (LB), wherein the airflow is applied at the upper and lower regions of the slope, respectively. Results indicate that the rate of temperature variation in the shallow soil layer subjected to forced convection is nearly an order of magnitude higher compared to natural convection, leading to accelerated freezing front migration and the initiation of shallow cracks. These cracks gradually evolve into shallow transverse tensile fractures and deep multi-layered slip surfaces. The direction of convection alters the THM response within the slope, ultimately controlling the slope failure process: Upper-blowing flow fields generate non-uniform conditions that activate crest-originated ratcheting effects, inducing downward arcuate sliding failures, whereas lower-blowing flow fields create quasi-uniform temperature gradients that suppress localized stress concentrations, resulting in stepwise potential slip surfaces parallel to the slope. This study underscores the importance of accurately modeling the atmosphere-soil interface for slope maintenance and hazard mitigation in cold regions.
{"title":"Influence of interface flow field on slope deterioration mechanism under freeze–thaw cycles: insights from physical model testing","authors":"Jiaming Zhang , Hao Xu , Xingyu Gao , Teng Liang , Xuecheng Bian","doi":"10.1016/j.trgeo.2026.101936","DOIUrl":"10.1016/j.trgeo.2026.101936","url":null,"abstract":"<div><div>The process of forced convection heat transfer at the atmosphere-soil interface modifies thermal boundary conditions, thereby influencing internal thermo-hydro-mechanical (THM) responses and triggering progressive slope instability. While existing studies on freeze–thaw-induced slope deterioration either employ natural convection boundary or conductive heat transfer boundary to investigate soil responses, yet the effects of forced convection on slope degradation processes have rarely been considered. To address this gap, a novel freeze–thaw cycling apparatus was developed to simulate convective heat transfer boundaries at the atmosphere-soil interface. Physical model tests were conducted under two distinct flow fields characterized by different convection directions: upper-blowing (UB) and lower-blowing (LB), wherein the airflow is applied at the upper and lower regions of the slope, respectively. Results indicate that the rate of temperature variation in the shallow soil layer subjected to forced convection is nearly an order of magnitude higher compared to natural convection, leading to accelerated freezing front migration and the initiation of shallow cracks. These cracks gradually evolve into shallow transverse tensile fractures and deep multi-layered slip surfaces. The direction of convection alters the THM response within the slope, ultimately controlling the slope failure process: Upper-blowing flow fields generate non-uniform conditions that activate crest-originated ratcheting effects, inducing downward arcuate sliding failures, whereas lower-blowing flow fields create quasi-uniform temperature gradients that suppress localized stress concentrations, resulting in stepwise potential slip surfaces parallel to the slope. This study underscores the importance of accurately modeling the atmosphere-soil interface for slope maintenance and hazard mitigation in cold regions.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101936"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190496","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 : 2026-03-01Epub Date: 2026-01-27DOI: 10.1016/j.trgeo.2026.101915
Pengyi Zhang , Bowen Tai , Qingzhi Wang , Xianwei Zhang , Dongmei Zhang , Jianhong Fang , Jiankun Liu
In permafrost tunnels on the Qinghai–Tibet Plateau, the coupled effects of freeze–thaw (FT) cycles and confining pressure pose a significant threat to the long-term stability of defective surrounding rocks. In this study, red sandstone specimens with different hole numbers (complete, single-hole, and double-hole) were subjected to FT treatment, followed by conventional triaxial compression and nuclear magnetic resonance (NMR) tests. Based on these results, a Hoek–Brown constitutive model was established to elucidate the influence of hole number on the evolution mechanism of FT-induced damage. The results show that as the number of FT cycles increases, the mass gain, volumetric expansion, and P-wave velocity attenuation of holed specimens are lower than those of intact specimens, indicating that holes can locally relieve stress and delay frost damage. However, their cohesion, internal friction angle, elastic modulus, and peak strength deteriorate more significantly, with damage severity increasing with both hole number and confining pressure. NMR analyses reveal that intact specimens mainly develop medium-to-large pores, while specimens with holes are dominated by micropore accumulation, accompanied by a shift in failure mode from single-shear to ring-shaped or mixed patterns. The Hoek–Brown-based constitutive analysis further demonstrates the dual role of holes: under zero confinement, holes mitigate damage evolution, whereas under confinement, they act as amplifying factors that accelerate degradation. The proposed mechanistic framework not only clarifies the experimental and numerical findings but also provides a theoretical basis for predicting degradation and assessing the stability of defective surrounding rock in cold-region tunnels.
{"title":"Dual role of holes in red sandstone under freeze–thaw and confinement: mechanistic insights and a Hoek–Brown-based predictive model","authors":"Pengyi Zhang , Bowen Tai , Qingzhi Wang , Xianwei Zhang , Dongmei Zhang , Jianhong Fang , Jiankun Liu","doi":"10.1016/j.trgeo.2026.101915","DOIUrl":"10.1016/j.trgeo.2026.101915","url":null,"abstract":"<div><div>In permafrost tunnels on the Qinghai–Tibet Plateau, the coupled effects of freeze–thaw (FT) cycles and confining pressure pose a significant threat to the long-term stability of defective surrounding rocks. In this study, red sandstone specimens with different hole numbers (complete, single-hole, and double-hole) were subjected to FT treatment, followed by conventional triaxial compression and nuclear magnetic resonance (NMR) tests. Based on these results, a Hoek–Brown constitutive model was established to elucidate the influence of hole number on the evolution mechanism of FT-induced damage. The results show that as the number of FT cycles increases, the mass gain, volumetric expansion, and P-wave velocity attenuation of holed specimens are lower than those of intact specimens, indicating that holes can locally relieve stress and delay frost damage. However, their cohesion, internal friction angle, elastic modulus, and peak strength deteriorate more significantly, with damage severity increasing with both hole number and confining pressure. NMR analyses reveal that intact specimens mainly develop medium-to-large pores, while specimens with holes are dominated by micropore accumulation, accompanied by a shift in failure mode from single-shear to ring-shaped or mixed patterns. The Hoek–Brown-based constitutive analysis further demonstrates the dual role of holes: under zero confinement, holes mitigate damage evolution, whereas under confinement, they act as amplifying factors that accelerate degradation. The proposed mechanistic framework not only clarifies the experimental and numerical findings but also provides a theoretical basis for predicting degradation and assessing the stability of defective surrounding rock in cold-region tunnels.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"58 ","pages":"Article 101915"},"PeriodicalIF":5.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190534","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}
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