Subgrade settlement is a common issue in soil ground within earthquake-prone regions,posing a threat to the safe operation of train-slab track coupled system(TSCS)in high-speed railways(HSRs).This study aims to analyz...Subgrade settlement is a common issue in soil ground within earthquake-prone regions,posing a threat to the safe operation of train-slab track coupled system(TSCS)in high-speed railways(HSRs).This study aims to analyze the mechanical behavior evolution of TSCS under subgrade settlement and earthquake excitation.The refined numerical model of slab track under subgrade differential settlement is established.The short settlement wavelength of 10 m causes the separation between the base and subgrade.The dynamic model of TSCS under subgrade settlement and earthquake excitation is developed.The dynamic response of TSCS exhibits more pronounced fluctuations under the combined effects of subgrade settlement and earthquake excitation than under the effects of settlement or earthquake alone.The evaluation indexes for the running safety of train on slab track under different settlement wavelengths exhibit varying degrees of increase with settlement amplitude and are particularly sensitive to the short settlement wavelength of 10 m.The wheel unloading rate and derailment coefficient of TSCS increase with earthquake intensity.Under the settlement wavelength of 10 m and amplitude of 20 mm,the wheel unloading rate of TSCS exceeds the allowable limit when the earthquake intensity exceeds 0.17g,and the derailment coefficient exceeds the allowable limit when the earthquake intensity surpasses 0.29g.展开更多
Purpose–The deformation of the roadbed is easily influenced by the external environment to improve the accuracy of high-speed railway subgrade settlement prediction.Design/methodology/approach–A high-speed railway s...Purpose–The deformation of the roadbed is easily influenced by the external environment to improve the accuracy of high-speed railway subgrade settlement prediction.Design/methodology/approach–A high-speed railway subgrade settlement interval prediction method using the secretary bird optimization(SBOA)algorithm to optimize the BP neural network under the premise of gray relational analysis is proposed.Findings–Using the SBOA algorithm to optimize the BP neural network,the optimal weights and thresholds are obtained,and the best parameter prediction model is combined.The data were collected from the sensors deployed through the subgrade settlement monitoring system,and the gray relational analysis is used to verify that all four influencing factors had a great correlation to the subgrade settlement,and the collected data are verified using the model.Originality/value–The experimental results show that the SBOA-BP model has higher prediction accuracy than the BP model,and the SBOA-BP model has a wider range of prediction intervals for a given confidence level,which can provide higher guiding value for practical engineering applications.展开更多
The settlement of widened highway subgrade in mountainous area is not only affected by the interaction between new and existing subgrade,but also seriously restricted by the external retaining wall.Based on the practi...The settlement of widened highway subgrade in mountainous area is not only affected by the interaction between new and existing subgrade,but also seriously restricted by the external retaining wall.Based on the practical engineering of half-filled and half-cut widened mountainous highway subgrade with external balance weight retaining wall(BWRW),a sophisticated finite element numerical model is established.The evolution law of subgrade settlement is revealed during the whole process of new subgrade filling and BWRW inclination after construction.The settlement component of subgrade is clarified considering whether the existing pavement continues to be used.The results show that the additional settlement caused by the BWRW inclination after construction cannot be ignored in the widening and reconstruction of mountainous highway subgrade.In addition,pursuant to the comprehensive design of subgrade and pavement,the component of subgrade settlement should be determined according to whether the existing pavement continues to be used,while considering the influence of BWRW inclination after construction.When the existing pavement continues to be used,the settlement of the existing subgrade is caused by the new subgrade filling and the BWRW inclination after construction.On the contrary,the settlement is only caused by the BWRW inclination after construction.展开更多
Epoxy asphalt pavement cracking caused by subgrade settlement is detrimental to the long-term safe service of roads.A threedimensional finite element model of epoxy asphalt pavement is established to investigate the e...Epoxy asphalt pavement cracking caused by subgrade settlement is detrimental to the long-term safe service of roads.A threedimensional finite element model of epoxy asphalt pavement is established to investigate the effects of subgrade settlement on the propagation of top-down cracking(TDC).The contour integral method is utilized to calculate the stress intensity factor(SIF)at the crack tip,and then the extended finite element method(XFEM)is used to analyze the propagation behavior of TDC under combined subgrade settlement and traffic loading.The results of these analyses indicate that increased subgrade settlement,stiffer surface layers,and softer bases will increase the SIF,resulting in a faster crack propagation rate.It is suggested that the use of epoxy asphalt materials in pavement structures can allow more subgrade settlement than conventional asphalt mixtures.However,when the base layer modulus is higher than 12500 MPa,the increase in surface modulus can decrease crack propagation length.Sensitivity analysis results demonstrate that subgrade settlement has the most significant impact on TDC propagation.The conclusions of this study are expected to provide a theoretical basis for crack prevention in the design and maintenance of pavement structures.展开更多
The construction of municipal roads and bridges is an important foundation for the smooth traveling and transportation.However,if there a reduction in the subgrade and pavement part,the safety and the comfort of the d...The construction of municipal roads and bridges is an important foundation for the smooth traveling and transportation.However,if there a reduction in the subgrade and pavement part,the safety and the comfort of the driver will be seriously affected,therefore,reasonable measures should be taken on time to tackle the related issues.The significance of subgrade and pavement construction in the subsidence section,the key points of the construction,and the appropriate control measures that are should be taken in the actual construction,was discussed in this paper.Further,this paper analyzes the availability of the subgrade and pavement construction technology for the municipal roads and bridges,to provide a reference for engineers.展开更多
This study presents a laboratory investigation of load-settlement behaviour of a strip footing resting on iron ore tailings used as a structural fill.The footing was placed at various depths in the tailings bed.The re...This study presents a laboratory investigation of load-settlement behaviour of a strip footing resting on iron ore tailings used as a structural fill.The footing was placed at various depths in the tailings bed.The relative density of the tailings was varied as D_r = 50%,70%and 90%.An incremental load was applied on the footing while observing the settlement until the failure took place.The results obtained for tailings were compared with those for the sandy soil.It is observed that the load-bearing capacity and stiffness increase with an increase in footing embedment depth and relative density.Compared to load-settlement behaviour of Perth sandy soil,the tailings fill could have as high as 22 times and 13.5 times the load-bearing capacity and stiffness,respectively.Therefore,the replacement of sandy soil with iron ore tailings for structural fills is cost-effective,and moreover,this application contributes to environmental sustainability in construction.展开更多
基金Project(52078501)supported by the National Natural Science Foundation of ChinaProject(2022-Major-14)supported by the Science and Technology Research and Development Program Project of China Railway Group LimitedProject(2023ZZTS0342)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Subgrade settlement is a common issue in soil ground within earthquake-prone regions,posing a threat to the safe operation of train-slab track coupled system(TSCS)in high-speed railways(HSRs).This study aims to analyze the mechanical behavior evolution of TSCS under subgrade settlement and earthquake excitation.The refined numerical model of slab track under subgrade differential settlement is established.The short settlement wavelength of 10 m causes the separation between the base and subgrade.The dynamic model of TSCS under subgrade settlement and earthquake excitation is developed.The dynamic response of TSCS exhibits more pronounced fluctuations under the combined effects of subgrade settlement and earthquake excitation than under the effects of settlement or earthquake alone.The evaluation indexes for the running safety of train on slab track under different settlement wavelengths exhibit varying degrees of increase with settlement amplitude and are particularly sensitive to the short settlement wavelength of 10 m.The wheel unloading rate and derailment coefficient of TSCS increase with earthquake intensity.Under the settlement wavelength of 10 m and amplitude of 20 mm,the wheel unloading rate of TSCS exceeds the allowable limit when the earthquake intensity exceeds 0.17g,and the derailment coefficient exceeds the allowable limit when the earthquake intensity surpasses 0.29g.
文摘Purpose–The deformation of the roadbed is easily influenced by the external environment to improve the accuracy of high-speed railway subgrade settlement prediction.Design/methodology/approach–A high-speed railway subgrade settlement interval prediction method using the secretary bird optimization(SBOA)algorithm to optimize the BP neural network under the premise of gray relational analysis is proposed.Findings–Using the SBOA algorithm to optimize the BP neural network,the optimal weights and thresholds are obtained,and the best parameter prediction model is combined.The data were collected from the sensors deployed through the subgrade settlement monitoring system,and the gray relational analysis is used to verify that all four influencing factors had a great correlation to the subgrade settlement,and the collected data are verified using the model.Originality/value–The experimental results show that the SBOA-BP model has higher prediction accuracy than the BP model,and the SBOA-BP model has a wider range of prediction intervals for a given confidence level,which can provide higher guiding value for practical engineering applications.
基金supported by Sichuan Science and Technology Program(No.2019YFS0492)Key Laboratories Open Engineering Practice Program to Undergraduates of SWJTU(No.ZD2020010010)。
文摘The settlement of widened highway subgrade in mountainous area is not only affected by the interaction between new and existing subgrade,but also seriously restricted by the external retaining wall.Based on the practical engineering of half-filled and half-cut widened mountainous highway subgrade with external balance weight retaining wall(BWRW),a sophisticated finite element numerical model is established.The evolution law of subgrade settlement is revealed during the whole process of new subgrade filling and BWRW inclination after construction.The settlement component of subgrade is clarified considering whether the existing pavement continues to be used.The results show that the additional settlement caused by the BWRW inclination after construction cannot be ignored in the widening and reconstruction of mountainous highway subgrade.In addition,pursuant to the comprehensive design of subgrade and pavement,the component of subgrade settlement should be determined according to whether the existing pavement continues to be used,while considering the influence of BWRW inclination after construction.When the existing pavement continues to be used,the settlement of the existing subgrade is caused by the new subgrade filling and the BWRW inclination after construction.On the contrary,the settlement is only caused by the BWRW inclination after construction.
基金supported by the Major Science and Technology Project of Nanjing(Grant No.202209012)the Carbon Peak and Carbon Neutrality Science and Technology Innovation Special Funds of Jiangsu Province(Grant No.BE2022615)2024 Jiangsu Provincial Graduate Student Research and Innovation Program(Grant No.KYCX24_0449).
文摘Epoxy asphalt pavement cracking caused by subgrade settlement is detrimental to the long-term safe service of roads.A threedimensional finite element model of epoxy asphalt pavement is established to investigate the effects of subgrade settlement on the propagation of top-down cracking(TDC).The contour integral method is utilized to calculate the stress intensity factor(SIF)at the crack tip,and then the extended finite element method(XFEM)is used to analyze the propagation behavior of TDC under combined subgrade settlement and traffic loading.The results of these analyses indicate that increased subgrade settlement,stiffer surface layers,and softer bases will increase the SIF,resulting in a faster crack propagation rate.It is suggested that the use of epoxy asphalt materials in pavement structures can allow more subgrade settlement than conventional asphalt mixtures.However,when the base layer modulus is higher than 12500 MPa,the increase in surface modulus can decrease crack propagation length.Sensitivity analysis results demonstrate that subgrade settlement has the most significant impact on TDC propagation.The conclusions of this study are expected to provide a theoretical basis for crack prevention in the design and maintenance of pavement structures.
文摘The construction of municipal roads and bridges is an important foundation for the smooth traveling and transportation.However,if there a reduction in the subgrade and pavement part,the safety and the comfort of the driver will be seriously affected,therefore,reasonable measures should be taken on time to tackle the related issues.The significance of subgrade and pavement construction in the subsidence section,the key points of the construction,and the appropriate control measures that are should be taken in the actual construction,was discussed in this paper.Further,this paper analyzes the availability of the subgrade and pavement construction technology for the municipal roads and bridges,to provide a reference for engineers.
文摘This study presents a laboratory investigation of load-settlement behaviour of a strip footing resting on iron ore tailings used as a structural fill.The footing was placed at various depths in the tailings bed.The relative density of the tailings was varied as D_r = 50%,70%and 90%.An incremental load was applied on the footing while observing the settlement until the failure took place.The results obtained for tailings were compared with those for the sandy soil.It is observed that the load-bearing capacity and stiffness increase with an increase in footing embedment depth and relative density.Compared to load-settlement behaviour of Perth sandy soil,the tailings fill could have as high as 22 times and 13.5 times the load-bearing capacity and stiffness,respectively.Therefore,the replacement of sandy soil with iron ore tailings for structural fills is cost-effective,and moreover,this application contributes to environmental sustainability in construction.
