Transportation Geotechnics最新文献_第5页

Impact of plane strain state on the long-term cyclic behavior of sand under true triaxial tests

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-02-05 DOI: 10.1016/j.trgeo.2025.101512

Shao-Heng He , Zhi Ding , Mao-Xin Wang , Huan He

Limited laboratory studies have investigated the cyclic behavior of sands under plane strain state, despite the current extensive applications of the plane strain hypothesis in modeling the behavior of subgrade soils beneath long road embankments. This study aims to explore the traffic-induced deformation behavior of sand under plane strain state and compare it to the conventional triaxial stress state. A series of one-way high-cyclic tests were performed on Fujian sand under both states using a true triaxial apparatus, considering different cyclic stress levels, consolidation stresses, consolidation anisotropies, and relative densities. In the plane strain scenario, the deformation of the specimen in the direction of intermediate principal stress was restricted when the cyclic major principal stress was applied. The test results indicate that during long-term cyclic loading, the sand exhibits substantially lower accumulated axial and volumetric strains when subjected to plane strain state as opposed to the conventional triaxial state. The reduction effect of plane strain state on the accumulated axial strain was found to be distinctively correlated with the strain levels, regardless of the cyclic stress amplitude and relative density. A practical formula was developed to estimate the difference in accumulated axial strain between the plane strain and triaxial states. Additionally, the intermediate principal stress of specimens under plane strain state was observed to oscillate cyclically in accordance with the one-way vertical cyclic stress. The intermediate principal stress coefficient, triggered by vertical cyclic loading, is more pronounced under high deformation, with its magnitude dependent on the specific loading conditions.

{"title":"Impact of plane strain state on the long-term cyclic behavior of sand under true triaxial tests","authors":"Shao-Heng He , Zhi Ding , Mao-Xin Wang , Huan He","doi":"10.1016/j.trgeo.2025.101512","DOIUrl":"10.1016/j.trgeo.2025.101512","url":null,"abstract":"<div><div>Limited laboratory studies have investigated the cyclic behavior of sands under plane strain state, despite the current extensive applications of the plane strain hypothesis in modeling the behavior of subgrade soils beneath long road embankments. This study aims to explore the traffic-induced deformation behavior of sand under plane strain state and compare it to the conventional triaxial stress state. A series of one-way high-cyclic tests were performed on Fujian sand under both states using a true triaxial apparatus, considering different cyclic stress levels, consolidation stresses, consolidation anisotropies, and relative densities. In the plane strain scenario, the deformation of the specimen in the direction of intermediate principal stress was restricted when the cyclic major principal stress was applied. The test results indicate that during long-term cyclic loading, the sand exhibits substantially lower accumulated axial and volumetric strains when subjected to plane strain state as opposed to the conventional triaxial state. The reduction effect of plane strain state on the accumulated axial strain was found to be distinctively correlated with the strain levels, regardless of the cyclic stress amplitude and relative density. A practical formula was developed to estimate the difference in accumulated axial strain between the plane strain and triaxial states. Additionally, the intermediate principal stress of specimens under plane strain state was observed to oscillate cyclically in accordance with the one-way vertical cyclic stress. The intermediate principal stress coefficient, triggered by vertical cyclic loading, is more pronounced under high deformation, with its magnitude dependent on the specific loading conditions.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"52 ","pages":"Article 101512"},"PeriodicalIF":4.9,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644775","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}

引用次数: 0

Seismic stability analysis of anchored concave slopes

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-02-03 DOI: 10.1016/j.trgeo.2025.101505

Ahmad Rajabian, Farshid Vahedifard

Concave-facing profiles are frequently encountered in natural slopes and, more recently, in man-made slopes. The seismic stability of such concave slopes can be effectively improved by employing ground anchors. The concavity of the slope profile can be effective in the design of the soil anchoring system. Using the pseudo-static limit equilibrium (LE) approach and considering a rotational log-spiral failure mechanism, this paper analytically addresses the total anchor load required for the stability of concave soil slopes reinforced with pre-tensioned cable anchors under seismic loading conditions. The concave face of the slope is represented by a circular arc, the curvature of which is expressed by the mid-chord offset (MCO) parameter. A satisfactory agreement was found between the results predicted by the solution and those of the finite element method. The impact of profile concavity on the resulting total anchor load was explored by varying backslope inclination, vertical-to-horizontal seismic coefficient ratio, and the action point of the total anchor load. Further, a design example is presented to illustrate how the load of anchors for a given anchorage layout can be determined using the method. The results generally indicate that a concave slope requires less total anchor load to provide seismic stability compared to an equivalent planar one. However, the concavity impact decreases with increasing horizontal seismic coefficient and backslope inclination. Further, the direction of the vertical seismic coefficient was found to be effective on the impact of concavity.

{"title":"Seismic stability analysis of anchored concave slopes","authors":"Ahmad Rajabian, Farshid Vahedifard","doi":"10.1016/j.trgeo.2025.101505","DOIUrl":"10.1016/j.trgeo.2025.101505","url":null,"abstract":"<div><div>Concave-facing profiles are frequently encountered in natural slopes and, more recently, in man-made slopes. The seismic stability of such concave slopes can be effectively improved by employing ground anchors. The concavity of the slope profile can be effective in the design of the soil anchoring system. Using the pseudo-static limit equilibrium (LE) approach and considering a rotational log-spiral failure mechanism, this paper analytically addresses the total anchor load required for the stability of concave soil slopes reinforced with pre-tensioned cable anchors under seismic loading conditions. The concave face of the slope is represented by a circular arc, the curvature of which is expressed by the mid-chord offset (MCO) parameter. A satisfactory agreement was found between the results predicted by the solution and those of the finite element method. The impact of profile concavity on the resulting total anchor load was explored by varying backslope inclination, vertical-to-horizontal seismic coefficient ratio, and the action point of the total anchor load. Further, a design example is presented to illustrate how the load of anchors for a given anchorage layout can be determined using the method. The results generally indicate that a concave slope requires less total anchor load to provide seismic stability compared to an equivalent planar one. However, the concavity impact decreases with increasing horizontal seismic coefficient and backslope inclination. Further, the direction of the vertical seismic coefficient was found to be effective on the impact of concavity.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101505"},"PeriodicalIF":4.9,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348211","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}

引用次数: 0

Performance evaluation of longer crossties in railroad track transition zone: Finite element analysis and laboratory experimentation

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-02-01 DOI: 10.1016/j.trgeo.2025.101508

Jaeik Lee, Arthur de O. Lima, Marcus S. Dersch, J.Riley Edwards

Transition zones in railway tracks are characterized by abrupt changes in the track stiffness which induces differential track displacement and can result in settlement. Failure to promptly address these issues through maintenance activities can lead to accelerated track component degradation and a loss of passenger comfort. This study investigated the effectiveness of a conventional strategy involving the implementation of longer crossties to mitigate abrupt variation of track stiffness especially in the open track to bridge transition. The study initially explored various properties and layouts of elastomers (i.e., rubber pads) through finite element analysis (FEA) to determine the appropriate support condition as an alternative to ballast to ensure consistency across the tests. Different hardnesses and configurations of rubber pads were considered to replicate the behavior of the ballast, and a dual layer of 60 shore A rubber pads with 25 holes exhibited crosstie displacement of 0.16 in. (0.41 cm), aligning with the range of field data. Based on this selected support condition, three different crosstie lengths (i.e., 102 in. [259 cm], 132 in. [335 cm], and 168 in. [427 cm]) were evaluated through both FEA and laboratory experimentation. Modeling results showed a 4.2 % reduction in displacement under the rail seat for the 168 in. (427 cm) crosstie compared to the standard crosstie (i.e., 102 in. [259 cm]). Similarly, laboratory experimentation demonstrated an 8.2 % decrease in vertical rail displacement. These findings suggest that the implementation of longer crossties within the track transition zone may not be considered an ideal methodology for achieving a gradual increase in track stiffness.

{"title":"Performance evaluation of longer crossties in railroad track transition zone: Finite element analysis and laboratory experimentation","authors":"Jaeik Lee, Arthur de O. Lima, Marcus S. Dersch, J.Riley Edwards","doi":"10.1016/j.trgeo.2025.101508","DOIUrl":"10.1016/j.trgeo.2025.101508","url":null,"abstract":"<div><div>Transition zones in railway tracks are characterized by abrupt changes in the track stiffness which induces differential track displacement and can result in settlement. Failure to promptly address these issues through maintenance activities can lead to accelerated track component degradation and a loss of passenger comfort. This study investigated the effectiveness of a conventional strategy involving the implementation of longer crossties to mitigate abrupt variation of track stiffness especially in the open track to bridge transition. The study initially explored various properties and layouts of elastomers (i.e., rubber pads) through finite element analysis (FEA) to determine the appropriate support condition as an alternative to ballast to ensure consistency across the tests. Different hardnesses and configurations of rubber pads were considered to replicate the behavior of the ballast, and a dual layer of 60 shore A rubber pads with 25 holes exhibited crosstie displacement of 0.16 in. (0.41 cm), aligning with the range of field data. Based on this selected support condition, three different crosstie lengths (i.e., 102 in. [259 cm], 132 in. [335 cm], and 168 in. [427 cm]) were evaluated through both FEA and laboratory experimentation. Modeling results showed a 4.2 % reduction in displacement under the rail seat for the 168 in. (427 cm) crosstie compared to the standard crosstie (i.e., 102 in. [259 cm]). Similarly, laboratory experimentation demonstrated an 8.2 % decrease in vertical rail displacement. These findings suggest that the implementation of longer crossties within the track transition zone may not be considered an ideal methodology for achieving a gradual increase in track stiffness.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101508"},"PeriodicalIF":4.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139452","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}

引用次数: 0

An active drainage method for groundwater environment protection and tunnel safety control

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-02-01 DOI: 10.1016/j.trgeo.2025.101502

Ziquan Chen , Bingxin Yu , Zheng Li , Duanyang Zhuang , Maoyi Liu

The construction of tunnels in ecologically sensitive regions often seriously disturbs the balance of groundwater seepage fields. To control the stability of groundwater environment and consider the safety of tunnel structure, an active drainage method is proposed. Based on the Kexuecheng Tunnel in the mountainous city of Chongqing, China, theoretical calculations, numerical simulations and in-situ monitoring are applied to study the influence of the active drainage method on seepage and stress fields of small interval tunnels. The characteristics of tunnel groundwater discharge and water pressure under different drainage valve pressures and rainfall intensities are revealed, and the mechanical performance and safety factors of the tunnel lining are analyzed. The results indicate that the maximum shear stress and maximum tensile stress of the lining are located at the arch foot and bottom respectively, and increase with increasing groundwater level. Reducing the pressure of the drainage valve can increase the safety factor of the lining structure when excessive water pressure threatens the safety of tunnel structures. When the groundwater level drops too much, increasing the pressure of the drainage valve appropriately can reduce groundwater loss and help maintain the balance of the groundwater environment. In addition, the water pressure difference between the vault and bottom, as well as the water pressure asymmetry coefficient on the two sides of the tunnel, decrease with the increase of drainage valve pressure. Considering the tunnel water inflow, groundwater level change, water pressure and safety factors of lining, suitable drainage valve pressures are proposed for different rainfall intensities. An active drainage control system for tunnels in water-rich environment has been developed and applied, which can effectively achieve the dynamic balance between the groundwater level, water inflow and tunnel structural safety.

{"title":"An active drainage method for groundwater environment protection and tunnel safety control","authors":"Ziquan Chen , Bingxin Yu , Zheng Li , Duanyang Zhuang , Maoyi Liu","doi":"10.1016/j.trgeo.2025.101502","DOIUrl":"10.1016/j.trgeo.2025.101502","url":null,"abstract":"<div><div>The construction of tunnels in ecologically sensitive regions often seriously disturbs the balance of groundwater seepage fields. To control the stability of groundwater environment and consider the safety of tunnel structure, an active drainage method is proposed. Based on the Kexuecheng Tunnel in the mountainous city of Chongqing, China, theoretical calculations, numerical simulations and in-situ monitoring are applied to study the influence of the active drainage method on seepage and stress fields of small interval tunnels. The characteristics of tunnel groundwater discharge and water pressure under different drainage valve pressures and rainfall intensities are revealed, and the mechanical performance and safety factors of the tunnel lining are analyzed. The results indicate that the maximum shear stress and maximum tensile stress of the lining are located at the arch foot and bottom respectively, and increase with increasing groundwater level. Reducing the pressure of the drainage valve can increase the safety factor of the lining structure when excessive water pressure threatens the safety of tunnel structures. When the groundwater level drops too much, increasing the pressure of the drainage valve appropriately can reduce groundwater loss and help maintain the balance of the groundwater environment. In addition, the water pressure difference between the vault and bottom, as well as the water pressure asymmetry coefficient on the two sides of the tunnel, decrease with the increase of drainage valve pressure. Considering the tunnel water inflow, groundwater level change, water pressure and safety factors of lining, suitable drainage valve pressures are proposed for different rainfall intensities. An active drainage control system for tunnels in water-rich environment has been developed and applied, which can effectively achieve the dynamic balance between the groundwater level, water inflow and tunnel structural safety.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101502"},"PeriodicalIF":4.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143261734","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}

引用次数: 0

An iterative program to back-analyze grain-size distribution from a predetermined soil–water characteristic curve

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-27 DOI: 10.1016/j.trgeo.2025.101485

Minh Nguyen , David Elwood

Numerous methods for predicting unsaturated soil properties based on basic soil parameters have been introduced to reduce the cost of unsaturated soil testing. This research proposes an unsaturated soil estimation program that uses a predetermined soil–water characteristic curve (SWCC) to predict the grain-size distribution (GSD) using computer iteration. The results indicate back-calculating a GSD from a given SWCC is possible, and that different GSDs can produce the same SWCC. A Monte Carlo approach examining variations of the GSD was conducted and associated packing porosities are provided. The program was tested on coarse- and fine-grained soils to determine the program’s capability and indicate it is appropriate for samples dominated by silty sand and silt but not clay. The back-analysis program described here could bypass the arduous testing phase of multiple soils to find a suitable SWCC for a capillary break layer as it can start with a predetermined SWCC and estimate a suitable GSD. In such efforts, the most important characteristic (i.e., strength or stiffness) of a soil must be determined when considering the GSD required because an infinite number of GSDs with similar properties could produce the same SWCC.

{"title":"An iterative program to back-analyze grain-size distribution from a predetermined soil–water characteristic curve","authors":"Minh Nguyen , David Elwood","doi":"10.1016/j.trgeo.2025.101485","DOIUrl":"10.1016/j.trgeo.2025.101485","url":null,"abstract":"<div><div>Numerous methods for predicting unsaturated soil properties based on basic soil parameters have been introduced to reduce the cost of unsaturated soil testing. This research proposes an unsaturated soil estimation program that uses a predetermined soil–water characteristic curve (SWCC) to predict the grain-size distribution (GSD) using computer iteration. The results indicate back-calculating a GSD from a given SWCC is possible, and that different GSDs can produce the same SWCC. A Monte Carlo approach examining variations of the GSD was conducted and associated packing porosities are provided. The program was tested on coarse- and fine-grained soils to determine the program’s capability and indicate it is appropriate for samples dominated by silty sand and silt but not clay. The back-analysis program described here could bypass the arduous testing phase of multiple soils to find a suitable SWCC for a capillary break layer as it can start with a predetermined SWCC and estimate a suitable GSD. In such efforts, the most important characteristic (i.e., strength or stiffness) of a soil must be determined when considering the GSD required because an infinite number of GSDs with similar properties could produce the same SWCC.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101485"},"PeriodicalIF":4.9,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Forensic investigation and chemical remediation of a collapsed highway embankment slope in Houston, Texas

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-25 DOI: 10.1016/j.trgeo.2025.101503

Ayush Kumar , Nripojyoti Biswas , Anand J. Puppala , Benamar Mebarkia

Transportation infrastructure, such as highway embankment slopes and retaining walls, are often constructed using locally available fill materials. Slopes constructed with such fills can pose problems as those fills can be expansive and experience surficial failures due to significant strength reductions over the years from cyclic moisture ingress and egress. Repeated wetting and drying cycles often result in the formation of desiccation cracks, which, when compounded by rainfall events, lead to moisture infiltration in the cracks and cause surficial slope failures. This paper provides a forensic investigation conducted on one such collapsed highway embankment slope in Houston, Texas, employing exhaustive timeseries optical image analysis, site characterization, laboratory studies, and numerical modeling. In-situ investigations included determining the site properties using the Texas cone penetration test and retrieving augered soil specimens. Site characterization indicated that the embankment soil was expansive in nature and susceptible to moisture-induced distress. Subsequently, laboratory shear strength studies were performed, and it was determined that the loss in cohesion in the problematic clay during the fully softening stage was responsible for initiating slope failure. Shallow slope failure was often attributed to surficial cracking due to moisture migration and reduction in shear strength from peak to fully-softened, and further aggravated by insufficient drainage along the slope and vegetation removal. Surficial soil treatment with a calcium-based stabilizer was determined as a potential mitigation method. Engineering studies and numerical analyses showed that soil stabilization using calcium-based stabilizers notably enhanced the mechanical strength properties and overall stability of the slope under future extreme precipitation conditions. Overall, the study emphasized the importance of moisture regulation and the inclusion of anticipated rainfall projections within numerical models along with suitable chemical stabilizers to stabilize problematic embankment subgrade conditions in order to ensure an adequate performance of transportation infrastructure for long-term serviceability.

{"title":"Forensic investigation and chemical remediation of a collapsed highway embankment slope in Houston, Texas","authors":"Ayush Kumar , Nripojyoti Biswas , Anand J. Puppala , Benamar Mebarkia","doi":"10.1016/j.trgeo.2025.101503","DOIUrl":"10.1016/j.trgeo.2025.101503","url":null,"abstract":"<div><div>Transportation infrastructure, such as highway embankment slopes and retaining walls, are often constructed using locally available fill materials. Slopes constructed with such fills can pose problems as those fills can be expansive and experience surficial failures due to significant strength reductions over the years from cyclic moisture ingress and egress. Repeated wetting and drying cycles often result in the formation of desiccation cracks, which, when compounded by rainfall events, lead to moisture infiltration in the cracks and cause surficial slope failures. This paper provides a forensic investigation conducted on one such collapsed highway embankment slope in Houston, Texas, employing exhaustive timeseries optical image analysis, site characterization, laboratory studies, and numerical modeling. In-situ investigations included determining the site properties using the Texas cone penetration test and retrieving augered soil specimens. Site characterization indicated that the embankment soil was expansive in nature and susceptible to moisture-induced distress. Subsequently, laboratory shear strength studies were performed, and it was determined that the loss in cohesion in the problematic clay during the fully softening stage was responsible for initiating slope failure. Shallow slope failure was often attributed to surficial cracking due to moisture migration and reduction in shear strength from peak to fully-softened, and further aggravated by insufficient drainage along the slope and vegetation removal. Surficial soil treatment with a calcium-based stabilizer was determined as a potential mitigation method. Engineering studies and numerical analyses showed that soil stabilization using calcium-based stabilizers notably enhanced the mechanical strength properties and overall stability of the slope under future extreme precipitation conditions. Overall, the study emphasized the importance of moisture regulation and the inclusion of anticipated rainfall projections within numerical models along with suitable chemical stabilizers to stabilize problematic embankment subgrade conditions in order to ensure an adequate performance of transportation infrastructure for long-term serviceability.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101503"},"PeriodicalIF":4.9,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139454","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}

引用次数: 0

Laboratory model test of contact erosion in railway substructure

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-22 DOI: 10.1016/j.trgeo.2025.101499

Shaoheng Dai , Xuzhen He , Feng Gao , Wenhua Zhong , Yewei Zheng , Sheng Zhang

The underestimated risk of contact erosion failure in railway substructures poses a significant threat to railway safety, particularly at the interface between the ballast/subballast and subgrade. The larger constriction size at this interface exacerbates the potential for long-term erosion, necessitating attention to safeguard railway integrity. This study introduces a novel laboratory erosion testing apparatus to evaluate contact erosion at the subballast-subgrade interface under cyclic loading. Subgrade soils with varying fines contents are tested, and the effect of pressure head on erosion is investigated in detail. The results indicate that sandy soil with higher internal stability exhibits a higher critical pressure head for contact erosion. Cyclic loading induces oscillations in pore water pressure within the subballast layer, with higher pressure heads leading to larger amplitudes. Excess pore water pressure is generated in the sandy soil layer during cyclic loading and gradually dissipates over time. Fine eroded particles migrate into the subballast layer, forming mud, while coarse eroded particles accumulate at the base, creating low-permeability interlayers. Notably, the geometric conditions alone may not guarantee effective prevention of contact erosion in railway substructures. The hydraulic conditions for contact erosion are more easily achieved under cyclic loading compared to static loading. These distinctive features of contact erosion in railway substructures, different from those observed in hydraulic structures, provide some insights for the development of remediation strategies and improvements in railway substructure design.

{"title":"Laboratory model test of contact erosion in railway substructure","authors":"Shaoheng Dai , Xuzhen He , Feng Gao , Wenhua Zhong , Yewei Zheng , Sheng Zhang","doi":"10.1016/j.trgeo.2025.101499","DOIUrl":"10.1016/j.trgeo.2025.101499","url":null,"abstract":"<div><div>The underestimated risk of contact erosion failure in railway substructures poses a significant threat to railway safety, particularly at the interface between the ballast/subballast and subgrade. The larger constriction size at this interface exacerbates the potential for long-term erosion, necessitating attention to safeguard railway integrity. This study introduces a novel laboratory erosion testing apparatus to evaluate contact erosion at the subballast-subgrade interface under cyclic loading. Subgrade soils with varying fines contents are tested, and the effect of pressure head on erosion is investigated in detail. The results indicate that sandy soil with higher internal stability exhibits a higher critical pressure head for contact erosion. Cyclic loading induces oscillations in pore water pressure within the subballast layer, with higher pressure heads leading to larger amplitudes. Excess pore water pressure is generated in the sandy soil layer during cyclic loading and gradually dissipates over time. Fine eroded particles migrate into the subballast layer, forming mud, while coarse eroded particles accumulate at the base, creating low-permeability interlayers. Notably, the geometric conditions alone may not guarantee effective prevention of contact erosion in railway substructures. The hydraulic conditions for contact erosion are more easily achieved under cyclic loading compared to static loading. These distinctive features of contact erosion in railway substructures, different from those observed in hydraulic structures, provide some insights for the development of remediation strategies and improvements in railway substructure design.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101499"},"PeriodicalIF":4.9,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Method for calculating embankment load induced vertical stress increments under reinforced concrete box culvert − a case study

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-22 DOI: 10.1016/j.trgeo.2025.101500

Jinchun Chai , Yafei Qiao (*) , Wenqi Ding , Junfeng Ni , Takenori Hino , Toshihiro Kirekawa

For the convenience of designing reinforced concrete (RC) box culverts in road/railway transportation systems, a practical graphic method for evaluating the vertical stress increments under an RC box culvert has been developed. Firstly, like Osterberg’s method, influence values for the vertical stress increments under the shoulder, the middle of the slope, and the toe of an embankment have been newly produced in graphic forms. Secondly, a graphic form correction factor (α₁) has been created to consider the vertical load difference between an RC box culvert location and the both side embankments. Then multiplying the vertical stress increments from an embankment load by α₁, the desired vertical stress increments under an RC box culvert can be obtained. The method was applied to a road RC box culvert in Saga, Japan, to demonstrate its usefulness. With the evaluated vertical stress increments, settlements under the RC box culvert were calculated and they are comparable with the field measurements. Further investigation about this case history regarding to the effects of soil–cement columns under the box culvert was carried out by finite element analysis.

{"title":"Method for calculating embankment load induced vertical stress increments under reinforced concrete box culvert − a case study","authors":"Jinchun Chai , Yafei Qiao (*) , Wenqi Ding , Junfeng Ni , Takenori Hino , Toshihiro Kirekawa","doi":"10.1016/j.trgeo.2025.101500","DOIUrl":"10.1016/j.trgeo.2025.101500","url":null,"abstract":"<div><div>For the convenience of designing reinforced concrete (RC) box culverts in road/railway transportation systems, a practical graphic method for evaluating the vertical stress increments under an RC box culvert has been developed. Firstly, like Osterberg’s method, influence values for the vertical stress increments under the shoulder, the middle of the slope, and the toe of an embankment have been newly produced in graphic forms. Secondly, a graphic form correction factor (<em>α</em><sub>1</sub>) has been created to consider the vertical load difference between an RC box culvert location and the both side embankments. Then multiplying the vertical stress increments from an embankment load by <em>α</em><sub>1</sub>, the desired vertical stress increments under an RC box culvert can be obtained. The method was applied to a road RC box culvert in Saga, Japan, to demonstrate its usefulness. With the evaluated vertical stress increments, settlements under the RC box culvert were calculated and they are comparable with the field measurements. Further investigation about this case history regarding to the effects of soil–cement columns under the box culvert was carried out by finite element analysis.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101500"},"PeriodicalIF":4.9,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139916","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}

引用次数: 0

Experimental Study on the Dynamic Responses of Subgrade and Foundation of High-Speed Railway Crossing Ground Fissure Zone

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-21 DOI: 10.1016/j.trgeo.2025.101498

Linfeng Gao , Qiangbing Huang , Yuxuan Gou , Bo Peng , Qingyu Xie

Ground fissures are widely distributed in China, as a geological hazard that can aggravate overall deformation of subgrade and foundation of high-speed railways and seriously affect the construction, operation, and maintenance. To reveal the impact of ground fissures, a physical model test of dynamic responses of subgrade and foundation of high-speed railway was conducted. The variation of dynamic responses of CFG (cement, flying-ash, and gravel) piles, foundation, and subgrade at different train speeds are studied, with the differences of dynamic responses of natural and composite foundations. The results show that the dynamic amplification effect of hanging wall is significant than that of footwall under the action of train vibration load, due to the asymmetric distribution of inclined strata in the ground fissure site. Because of different capacities to scatter and absorb dynamic waves, the attenuation rate of the dynamic responses in the subgrade is greater than that of foundation, resulting in dynamic stress and acceleration attenuation of about 85 % and 53 % in the embankment, respectively. Moreover, there is a linear relationship between the influence depth of dynamic stress and the train speed, which of the hanging wall and footwall are respectively 10.8 m and 9.8 m at the train speed of 250 km/h. The amplification factor of soil between piles near the ground fissure is greater than that of pile heads, due to the greater stiffness of the CFG piles. The dynamic strain amplitudes of piles decrease with the increase of depth, and are basically symmetrical about the central axis along the transverse direction of the subgrade. The amplitudes of dynamic responses in natural foundation are greater than that in composite foundation due to the reinforcement effect of CFG piles, and the attenuation rates are less than those of the composite foundation along the depth direction.

{"title":"Experimental Study on the Dynamic Responses of Subgrade and Foundation of High-Speed Railway Crossing Ground Fissure Zone","authors":"Linfeng Gao , Qiangbing Huang , Yuxuan Gou , Bo Peng , Qingyu Xie","doi":"10.1016/j.trgeo.2025.101498","DOIUrl":"10.1016/j.trgeo.2025.101498","url":null,"abstract":"<div><div>Ground fissures are widely distributed in China, as a geological hazard that can aggravate overall deformation of subgrade and foundation of high-speed railways and seriously affect the construction, operation, and maintenance. To reveal the impact of ground fissures, a physical model test of dynamic responses of subgrade and foundation of high-speed railway was conducted. The variation of dynamic responses of CFG (cement, flying-ash, and gravel) piles, foundation, and subgrade at different train speeds are studied, with the differences of dynamic responses of natural and composite foundations. The results show that the dynamic amplification effect of hanging wall is significant than that of footwall under the action of train vibration load, due to the asymmetric distribution of inclined strata in the ground fissure site. Because of different capacities to scatter and absorb dynamic waves, the attenuation rate of the dynamic responses in the subgrade is greater than that of foundation, resulting in dynamic stress and acceleration attenuation of about 85 % and 53 % in the embankment, respectively. Moreover, there is a linear relationship between the influence depth of dynamic stress and the train speed, which of the hanging wall and footwall are respectively 10.8 m and 9.8 m at the train speed of 250 km/h. The amplification factor of soil between piles near the ground fissure is greater than that of pile heads, due to the greater stiffness of the CFG piles. The dynamic strain amplitudes of piles decrease with the increase of depth, and are basically symmetrical about the central axis along the transverse direction of the subgrade. The amplitudes of dynamic responses in natural foundation are greater than that in composite foundation due to the reinforcement effect of CFG piles, and the attenuation rates are less than those of the composite foundation along the depth direction.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101498"},"PeriodicalIF":4.9,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139449","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}

引用次数: 0

Investigating the particle migration and dynamic characteristics in ballasted track subgrade under intermittent load-wetting coupling

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-21 DOI: 10.1016/j.trgeo.2025.101501

Bowen Han , Guoqing Cai , Yanlin Su , Yepeng Shan , Jian Li

Existing ballasted track subgrades are prone to complex particle migration problems due to intermittent train load-rainfall wetting coupling, which causes mud pumping in severe cases. In this work, a model test on a ballast layer overlying a fine particle layer was conducted under intermittent load-wetting coupling conditions. The experimental results indicate that the coupling effect of intermittent loading and wetting has a significant effect on the increase in the volumetric water content and pore water pressure. The changes in the accumulated deformation, resilient modulus, damping ratio, and particle migration phenomenon mainly occur in the first three loading stages (LS1–LS3 stages), and the changes are most significant in the second loading stage (LS2 stage) because of the high saturation and low density of the soils. During the subsequent loading stages, the changes in the accumulated deformation, resilient modulus, damping ratio, and particle migration phenomenon are not obvious because of the high density of the soils. A low level of resilience occurs during intermittent periods (IS4–IS7). At the end of the test, the ballast fouling index (FI) was 16.4%, reaching a moderate fouling level. Timely replacement and rectification should be conducted for sections that produce mud pumping and ballast fouling.

{"title":"Investigating the particle migration and dynamic characteristics in ballasted track subgrade under intermittent load-wetting coupling","authors":"Bowen Han , Guoqing Cai , Yanlin Su , Yepeng Shan , Jian Li","doi":"10.1016/j.trgeo.2025.101501","DOIUrl":"10.1016/j.trgeo.2025.101501","url":null,"abstract":"<div><div>Existing ballasted track subgrades are prone to complex particle migration problems due to intermittent train load-rainfall wetting coupling, which causes mud pumping in severe cases. In this work, a model test on a ballast layer overlying a fine particle layer was conducted under intermittent load-wetting coupling conditions. The experimental results indicate that the coupling effect of intermittent loading and wetting has a significant effect on the increase in the volumetric water content and pore water pressure. The changes in the accumulated deformation, resilient modulus, damping ratio, and particle migration phenomenon mainly occur in the first three loading stages (LS1–LS3 stages), and the changes are most significant in the second loading stage (LS2 stage) because of the high saturation and low density of the soils. During the subsequent loading stages, the changes in the accumulated deformation, resilient modulus, damping ratio, and particle migration phenomenon are not obvious because of the high density of the soils. A low level of resilience occurs during intermittent periods (IS4–IS7). At the end of the test, the ballast fouling index (FI) was 16.4%, reaching a moderate fouling level. Timely replacement and rectification should be conducted for sections that produce mud pumping and ballast fouling.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"51 ","pages":"Article 101501"},"PeriodicalIF":4.9,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139448","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}

引用次数: 0