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Numerical analysis of high‑speed railway slab tracks using calibrated and validated 3D time‑domain modelling

Railway Engineering Science 2024年第1期32卷 36-58页

作者： A.F.Esen O.Laghrouche P.K.Woodward D.Medina‑Pineda Q.Corbisez J.Y.Shih D.P.Connolly Institute for High‑Speed Rail and System Integration University of LeedsLeeds LS29JTUK Institute for Infrastructure and Environment Heriot-Watt UniversityEdinburgh EH144ASUK Alstom Transport Saint‑OuenFrance Birmingham Centre for Railway Research and Education University of BirminghamBirmingham B152TTUK

Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance frequency.In this paper,the elastic performance of a novel slab trackform for high-speed railways is investigated using three-dimensional finite element modelling in Abaqus.It is then compared to the performance of a ballasted track.First,slab and ballasted track models are developed to replicate the full-scale testing of track sections.Once the models are calibrated with the experimental results,the novel slab model is developed and compared against the calibrated slab track results.The slab and ballasted track models are then extended to create linear dynamic models,considering the track geodynamics,and simulating train passages at various speeds,for which the Ledsgard documented case was used to validate the models.Trains travelling at low and high speeds are analysed to investigate the track deflections and the wave propagation in the soil,considering the issues associated with critical speeds.Various train loading methods are discussed,and the most practical approach is retained and described.Moreover,correlations are made between the geotechnical parameters of modern high-speed rail and conventional standards.It is found that considering the same ground condition,the slab track deflections are considerably smaller than those of the ballasted track at high speeds,while they show similar behaviour at low speeds.

关键词： High-speed railways Slab track New ballastless track ballasted track Critical speeds Finite element modelling Calibration of numerical models

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GPU-Based Simulation of Dynamic Characteristics of ballasted Railway track with Coupled Discrete-Finite Element Method

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Computer Modeling in Engineering & Sciences 2021年第2期126卷 645-671页

作者： Xu Li YingYan Shuai Shao Shunying Ji State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian116023China School of Civil Engineering Dalian Jiaotong UniversityDalian116028China Transportation Institute Inner Mongolia UniversityHohhot010070China

Considering the interaction between a sleeper,ballast layer,and substructure,a three-dimensional coupled discrete-finite element method for a ballasted railway track is proposed in this study.Ballast granules with irregular shapes are constructed using a clump model using the discrete element method.Meanwhile,concrete sleepers,embankments,and foundations are modelled using 20-node hexahedron solid elements using the finite element method.To improve computational efficiency,a GPU-based(Graphics Processing Unit)parallel framework is applied in the discrete element simulation.Additionally,an algorithm containing contact search and transfer parameters at the contact interface of discrete particles and finite elements is developed in the GPU parallel environment accordingly.A benchmark case is selected to verify the accuracy of the coupling algorithm.The dynamic response of the ballasted rail track is analysed under different train speeds and loads.Meanwhile,the dynamic stress on the substructure surface obtained by the established DEM-FEM model is compared with the in situ experimental results.Finally,stress and displacement contours in the cross-section of the model are constructed to further visualise the response of the ballasted railway.This proposed coupling model can provide important insights into high-performance coupling algorithms and the dynamic characteristics of full scale ballasted rail tracks.

关键词： ballasted track coupled discrete element-finite element method GPU parallel algorithm dynamic characteristics

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Mechanical properties of foamed polyurethane solidified ballasted track

High-Speed Railway

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High-Speed Railway 2023年第2期1卷 120-129页

作者： Yang Xu Luchao Qie Hong Wang Wenying Yu Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China

Foamed Polyurethane Solidified ballasted track(FPSBT),an innovative railway track,is formed by solidifying ballast bed with foamed polyurethane.Compared with the traditional Discrete ballasted track(DBT),FPSBT does not require regular maintenance such as tamping and cleaning.However,limited studies exist on the mechanical properties of FPSBT.In this study,Laboratory experiments are conducted on polyurethane samples to investigate the effects of polyurethane density on the mechanical properties of FPSBT.Furthermore,the performance of DBT and FPSBT with different polyurethane densities are compared,and the recommended polyurethane density is obtained.FPSBT exhibited negligible accumulation of deformation under cyclic loads,indicating excellent performance of FPSBT owing to the anti-deformation properties of polyurethane.Further,a track load vehicle test is conducted.FPSBT exhibited better load-transmitting ability than DBT.Finally,the construction and application of FPSBT in China are introduced.This study is expected to contribute to realizing a more extensive application of FPSBT.

关键词： ballasted track Foamed polyurethane Solidified track track load vehicle

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Analysis of the breakage parameters of railway ballast based on the discrete element method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第3期24卷 257-271页

作者： Gan-zhong LIU Jia-cheng DAI Ping WANG Rong CHEN Hao LIU Xian-kui WEI MOE Key Laboratory of High-speed Railway Engineering Southwest Jiaotong UniversityChengdu 610031China School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Amoy Transit Rail(AMTR) Xiamen MetroXiamen 361000China Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China Shudao Investment Group Co.Ltd. Chengdu 610031China

During the service lives of ballasted tracks,the ballast experiences degradation,such as breakage and fragmentation,which reduces the stability of the tracks.Ballast breakage is directly related to the shapes,sizes,and stress states of particles.The key to solving this problem is to determine the breakage parameters of railway ballast.In this study,through uniaxial compression and uniaxial shear tests,the factors associated with ballast breakage for a simple stress state were obtained.Then,a refined discrete element model of railway ballast was established.The Box-Behnken method was used to design a simulation test,and a response surface method was used to obtain the optimal ballast breakage parameters.Lastly,the results of a direct shear test were compared with the simulation results to verify the correctness of the parameters and to study the shear resistance of the ballast aggregates.The results showed that for ballast particles with sizes of 22.4–63.0 mm,the characteristic stresses of compression and shear were not significantly affected by the size of the particles,but were greatly affected by their shape.In particular,long particles were more likely to break.During the direct shear test,the cumulative ballast breakage ratio gradually increased to 13.97%.The optimal breakage parameters of the ballast determined by this approach have high application value in the management of ballasted tracks.

关键词： ballasted track Breakage parameters Discrete element method(DEM) Response surface

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Dynamic Response of Elastic Sleeper ballasted track on Bridge

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Journal of Southwest Jiaotong University(English Edition) 2010年第2期18卷 124-128页

作者：翟淼王平李培刚陈小平 School of Civil Engineering Southwest Jiaotong University

A vehicle-track-bridge coupling dynamics model was built based on the theory of vehicle-track coupling dynamics. Using this model, a comparison was made between the dynamic response of an elastic sleeper ballasted track and a common sleeper ballasted track on bridge under the same working conditions. The results show that laying elastic sleepers on the bridge could solve the problem of large track stiffness caused by a thin ballast thickness, and improve the dynamic response of the bridge. This is beneficial to train operation safety and riding comfort.

关键词： Elastic sleeper ballasted track Coupling dynamics Dynamic response Bridge

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Full-scale multi-functional test platform for investigating mechanical performance of track–subgrade systems of high-speed railways

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Railway Engineering Science 2020年第3期28卷 213-231页

作者： Wanming Zhai Kaiyun Wang Zhaowei Chen Shengyang Zhu Chengbiao Cai Gang Liu Train and track Research Institute State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu 610031China MOE Key Laboratory of High-speed Railway Engineering Southwest Jiaotong UniversityChengdu 610031China

Motivated by the huge practical engineering demand for the fundamental understanding of mechanical characteristics of high-speed railway infrastructure,a fullscale multi-functional test platform for high-speed railway track–subgrade system is developed in this paper,and its main functions for investigating the mechanical performance of track–subgrade systems are elaborated with three typical experimental examples.Comprising the full-scale subgrade structure and all the five types of track structures adopted in Chinese high-speed railways,namely the CRTS I,the CRTS II and the CRTS III ballastless tracks,the double-block ballastless track and the ballasted track,the test platform is established strictly according to the construction standard of Chinese high-speed railways.Three kinds of effective loading methods are employed,including the real bogie loading,multi-point loading and the impact loading.Various types of sensors are adopted in different components of the five types of track–subgrade systems to measure the displacement,acceleration,pressure,structural strain and deformation,etc.Utilizing this test platform,both dynamic characteristics and long-term performance evolution of high-speed railway track–subgrade systems can be investigated,being able to satisfy the actual demand for large-scale operation of Chinese high-speed railways.As examples,three typical experimental studies are presented to elucidate the comprehensive functionalities of the full-scale multi-functional test platform for exploring the dynamic performance and its long-term evolution of ballastless track systems and for studying the long-term accumulative settlement of the ballasted track–subgrade system in high-speed railways.Some interesting phenomena and meaningful results are captured by the developed test platform,which provide a useful guidance for the scientific operation and maintenance of high-speed railway infrastructure.

关键词： Full-scale test High-speed railway track–subgrade system Ballastless track ballasted track Mechanical performance Long-term performance evolution Damage and degradation

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The mechanism and effects of subgrade fluidisation under ballasted railway tracks

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Railway Engineering Science 2020年第2期28卷 113-128页

作者： Buddhima Indraratna Mandeep Singh Thanh Trung Nguyen Centre for Geomechanics and Railway Engineering University of WollongongWollongong CityNSW 2522Australia Australian Research Council(ARC)Industrial Transformation Training Centre ITTC-RailUniversity of WollongongWollongong CityNSW 2522Australia

The rapid growth in railway infrastructure and the construction of high-speed heavy-haul rail network,especially on ground that is basically unsuitable,poses challenges for geotechnical engineers because a large part of the money invested in the development of railway lines is often spent on track maintenance.In fact around the world,the mud pumping of subgrade fines is one of the common reasons why track performance deteriorates and track stability is hindered.This article presents a series of laboratory tests to examine following aspects of mud pumping:(1)the mechanisms of subgrade fluidisation under undrained condition,(2)the effects of mud pumping on the engineering characteristics of ballast,and(3)the use of vertical drains to stabilize subgrade under cyclic loads.The undrained cyclic triaxial testing on vulnerable soft subgrade was performed by varying the cyclic stress ratio(CSR)from 0.2 to 1.0 and the loading frequency f from 1.0 to 5.0 Hz.It is seen from the test results that for a specimen compacted at an initial dry density of 1790 kg/m3,the top portion of the specimen fluidises at CSR=0.5,irrespective of the applied loading frequency.Under cyclic railway loading,the internal redistribution of water at the top of the subgrade layer softens the soil and also reduces its stiffness.In response to these problems,this paper explains how the inclusion of vertical drains in soft subgrade will help to prevent mud pumping by alleviating the build-up of excess pore pressures under moving train loads.

关键词： Mud pumping ballasted track Subgrade fluidisation Fouled ballast Prefabricated vertical drains

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Experimental investigation of the dynamic behavior of railway track with sleeper voids

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Railway Engineering Science 2020年第3期28卷 290-304页

作者： Mykola Sysyn Olga Nabochenko Vitalii Kovalchuk Institute of Railway Systems and Public Transport Technical University of Dresden(TUD)DresdenSaxonyGermany Department of the Rolling Stock and track Lviv Branch of Dniprovsk National University of Railway TransportLvivUkraine

The deterioration of the sleeper support on the ballasted track begins with the accumulation of sleeper voids.The increased dynamic loading in the voided zone and the ballast contact conditions cause the accelerated growth of the settlements in the voided zones,which results in the appearance of local instabilities like ballast breakdown,white spots,subgrade defects,etc.The recent detection and quantification of the sleeper voids with track-side and onboard monitoring can help to avoid or delay the development of local instabilities.The present paper is devoted to the study of the dynamic behavior of railway track with sleeper voids in the ballast breakdown zone.The result of the experimental track-side measurements of rail acceleration and deflection is presented.The analysis shows the existence of the dynamic impact during wheel entry in the voided zone.However,the measured dynamic impact is subjected to the bias of the track-side measurement method.Both the mechanism of the impact and the measurement aspects are explained by using the one-beam model on viscoelastic foundation.The void features in the dynamic behavior are analyzed for the purpose of track-side and onboard monitoring.A practical method of the void parameter quantification is proposed.

关键词： ballasted track Sleeper voids Ballast breakdown track-side measurement Rail deflection Dynamic modeling Impact Identification

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A study on characteristic indexesof railway ballast bed underhigh-frequency radar

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Railway Sciences 2023年第1期2卷 33-47页

作者： Shilei Wang Zhan Peng Guixian Liu Weile Qiang Chi Zhang Infrastructure Inspection Research Institute China Academy of Railway Sciences Corporation LimitedBeijingChina

Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of railway ballast bed.Design/methodology/approach–Based on original radar signals,the time–frequency characteristics of radar signals were analyzed,five ballast bed condition characteristic indexes were proposed,including the frequency domain integral area,scanning area,number of intersections with the time axis,number of timedomain inflection points and amplitude envelope obtained by Hilbert transform,and the effectiveness and sensitivity of the indexes were analyzed.Findings–The thickness of ballast bed tested at the sleep bottom by high-frequency radar is up to 55 cm,which meets the requirements of ballast bed detection.Compared with clean ballast bed,the values of the five indexes of fouled ballast bed are larger,and the five indexes could effectively show the condition of the ballast bed.The computational efficiency of amplitude envelope obtained by Hilbert transform is 140 s$km1,and the computational efficiency of other indexes is 5 s$km1.The amplitude envelopes obtained by Hilbert transform in the subgrade sections and tunnel sections are the most sensitive,followed by scanning area.The number of intersections with the time axis in the bridge sections was the most sensitive,followed by the scanning area.The scanning area can adapt to different substructures such as subgrade,bridges and tunnels,with high comprehensive sensitivity.Originality/value–The research can provide appropriate characteristic indexes from the high-frequency radar original signal to quantitatively evaluate ballast bed condition under different substructures.

关键词： ballasted track Ballast bed High-frequency radar Test Time–frequency characteristics Characteristic indexes

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