Analytical study on high-speed railway track deformation under long-term bridge deformations and interlayer degradation

doi:10.1016/j.istruc.2020.10.079

Structures

Volume 29, February 2021, Pages 1005-1015

https://doi.org/10.1016/j.istruc.2020.10.079 Get rights and content

Highlights

•
The paper studies high-speed railway track deformation that affects safety of trains.
•
Long-term bridge deformations and interlayer degradation are considered.
•
Closed-form solutions are presented and compared with sophisticated finite element model.
•
The investigated deformations include pier settlement, fault of beam, and beam end rotation.
•
The effect of fastener stiffness on track deformation is investigated.

Abstract

Bridges are subjected to long-term deformations in addition to deformations under design loads. In high-speed railway bridges, long-term bridge deformation and potential degradation of materials may adversely impact the operation safety and riding comfort of the railway. While a high-speed railway network is being established in China, it is significant to understand the effects of long-term bridge deformation on track deformation for effective asset management. This study aims to develop an analytical model to investigate the roles of long-term bridge deformations and bridge-track interlayer degradation. Mechanical analysis is conducted to develop a track-bridge deformation model and derive closed-form solutions that can be applied in design and evaluation of high-speed railway bridges. The analytical study is validated against a three-dimensional finite element model, and used to investigate the effects of key parameters (e.g. bridge deformation amplitude, span length, fastener stiffness, and mortar layer stiffness). This study provides a method to quantitatively evaluate track deformation due to bridge deformations and interlayer degradation. With the developed formulae, real-time condition assessment of high-speed railway track can be performed based on real-time monitoring of bridge deformations.

Introduction

In the past decade, high-speed railway (HSR) was constructed in many countries to improve mobility and quality of life. In China, the mileage of HSR will exceed 38,000 km by 2025 [1]. A large percentage of the mileage of high-speed railway is on bridges, which are subjected to various additional deformations in addition to the deformations due to design loads. The additional deformation may be caused by cyclic loading of trains [2], shrinkage and creep of concrete [3], [4], [5], seismic load [6], [7], and other factors [8], [9]. The additional bridge deformations are cumulated over time, and cause deformations in the track, aggravating irregularity of track (rail) [10], [11]. Track irregularity directly affects the operation safety and riding comfort of trains, in particular, in the case of high-speed trains [12], [13], [14]. Therefore, it is important to study the relationship between bridge deformations and track (rail) geometry for safe operation of HSR.

In the literature, finite element analysis was conducted to investigate the geometrical change of tracks under bridge deformations [15], [16], [17], [18], [19]. Yang et al. [20] established a finite element model of track-bridge system to study the effect of concrete creep on track irregularity. Yang et al. [21] proposed a nonlinear finite element model and considered the load history in the investigation of interactions between track and bridge. He et al. [4] established a finite element model to study the influence of concrete creep and thermal effect on dynamic responses and operational safety of a train-bridge coupled system. Gou et al. [22], [23], [24] developed finite element models to analyze the effects of bridge deformations and track geometry on the safety of trains, and the thresholds of bridge deformations to ensure safety and riding comfort. While finite element models have shown adequate capability of analyzing track deformations under different types and magnitudes of bridge deformations, finite element analysis is costly in computation and time consuming, thus inconvenient in bridge design and railway operation.

To facilitate engineering practices, analytical models have been presented in the literature. Prior studies were mainly focused on the effect of uneven bridge pier settlement on track deformation [25], [26], [27], [28], [29]. Bridge pier settlement was found to cause additional deformation in the track installed on the bridge. In [27], [29], the dynamic behaviors of train-bridge coupled system were considered and used to evaluate the safety and riding comfort of high-speed trains. After that, more studies have been conducted to consider more types of factors on track deformation [2], [30], [31], [32], [33], [34]. For instance, Xiong et al. [30] studied the effect of concrete shrinkage and thermal expansion of bridge on track deformation. Wang [2] and Zhang et al. [32] studied the effects of concrete creep on track deformation and the dynamic responses of train using train-track-bridge coupled models.

Despite the above advancement in analytical studies, the past studies were mainly based on intact interactions between bridge and track. However, in real-life practice, there is unavoidable degradation for the bridge-track interlayer. Currently, the effect of interlayer condition on bridge-track deformation relationship remains unknown. In addition, each of the existing studies mainly investigated a single mode of bridge deformation, such as bridge pier settlement. However, in fact, a bridge is subjected to multiple types of deformations simultaneously. The typical types include beam faulting, beam end rotation, etc. It is essential to investigate the effects of multi-mode bridge deformations that can better represent realistic structural conditions.

Therefore, this study aims to develop an analytical model to investigate the roles of long-term bridge deformations and bridge-track interlayer degradation. Mechanical analysis is conducted to develop a track-bridge deformation model and derive closed-form solutions that can be applied in design and evaluation of high-speed railway bridges. The analytical study is validated against a three-dimension finite element model and used to investigate the effects of four key parameters, which are the bridge deformation amplitude, span length, fastener stiffness, and mortar layer stiffness. This study provides a method to quantitatively evaluate track deformation due to bridge deformations and interlayer degradation. With the developed formulae, real-time condition assessment of high-speed railway track can be performed based on bridge deformations that are monitored in real time.

Section snippets

Mechanical analysis

With a vertical deformation in the bridge, the track slab is deformed under gravity and the force of mortar layer. Then, the deformation causes a relative displacement of the track slab and the rail. Finally, the equilibrium condition is reached under the interaction of the geometrical position and deformation. In the analysis of the bridge and ballastless slab track, considering the connection between the base slab and track slab of the ballastless track along the bridge, the base slab and

Finite element model

A three-dimensional finite element model of a double-track four-span simply supported bridge is established using ABAQUS, and the finite element analysis results are used to validate the analytical formulae obtained from the aforementioned theoretical analysis. The lengths of the four spans are the same (32 m), and each span has a box section. The adopted railway track is CRTS II slab ballastless track (Fig. 3), which is made using reinforced concrete with a compressive strength of 60 MPa. The

Amplitudes of bridge deformations

Based on the analytical formulae of track-bridge deformations, this section investigates the effects of the three types of bridge deformations on track deformations. Fig. 5 shows the results of track deformations under different magnitudes of pier settlement, vertical fault, and beam end rotation at pier No. 3, respectively. As the magnitude of any one of the bridge deformations is increased gradually, the shape of the track deformation is retained, while the magnitude of the track deformation

Conclusions

This study develops an analytical model to map the bridge deformations to the geometry of the track. Based on the above investigations, the main conclusions can be drawn:

•
The developed analytical model provides reasonable predictions of track deformations under the investigated bridge deformations. Compared with the finite element model, the maximum error of the analytical formulae is 8%.
•
Under the same bridge deformation mode, the shape of track deformation does not change with the magnitude of

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

The research was funded by National Natural Science Foundation of China (Grant Number 51878563), Sichuan Science and Technology Program (Grant Numbers. 2018JY0294 and 2018JY0549), and Ministry of Science and Technology of China (Grant No. KY201801005).

References (35)

K.-M. Yun et al.
Quantification of ballasted track-bridge interaction behavior due to the temperature variation through field measurements
NDT E Int
(2019)
J. Zhang et al.
Loading-history-based track–bridge interaction analysis with experimental fastener resistance
Eng Struct
(2015)
X. He et al.
Recent developments of high-speed railway bridges in China
Struct Infrastruct Eng
(2017)
X.P. Wang
Influences of concrete creep and temperature deformation on vehicle travelling across bridge
Appl Mech Mater
(2014)
C. Vale et al.
A dynamic vehicle-track interaction model for predicting the track degradation process
J Infrastruct Syst
(2014)
H. Xia et al.
Dynamic interaction of train-bridge systems in high-speed railways: theory and applications
(2018)
A. Strauss et al.
Gamma prediction models for long-term creep deformations of prestressed concrete bridges
J Civ Eng Manag
(2017)
B. Yan et al.
Elastic-plastic seismic response of CRTS II slab ballastless track system on high-speed railway bridges
Sci China Technol Sci
(2017)
W. Liu et al.
Interaction between continuous welded rail and long-span steel truss arch bridge of a high-speed railway under seismic action
Struct Infrastruct Eng
(2018)
S.H. Hwang et al.
Effects of long-wavelength track irregularities due to thermal deformations of railway bridge on dynamic response of running train
Appl Sci
(2018)

S.-J. Wang et al.

Safety and stability of light-rail train running on multispan bridges with deformation

J Bridge Eng

(2016)

D.e. Zhang et al.

Effects of pier deformation on train operations within high-speed railway ballastless track–bridge systems

Transp Res Rec

(2018)

S.H. Ju

3D analysis of high-speed trains moving on bridges with foundation settlements

Arch Appl Mech

(2013)

H.Y. Gou et al.

In-situ test and dynamic response of a double-deck tied-arch bridge

Steel Compos Struct

(2018)

C.F. Hung et al.

Influence of long-wavelength track irregularities on the motion of a high-speed train

Veh Syst Dyn

(2018)

L.Z. Jiang et al.

Mapping the relationship between the structural deformation of a simply supported beam bridge and track deformation in high-speed railways

Proc Inst Mech Eng Part F J Rail Rapid Transit

(2019)

C.Y. He et al.

Dynamic behaviors of high speed train running through subgrade-bridge transition section

Cited by (30)

Vibration energy transmission in high-speed train-track-bridge coupled systems
2023, Engineering Structures
This paper investigates the vibration energy transmission characteristics of high-speed train-track-bridge coupled systems based on a high-speed railway in China. A coupled system composed of a CRH380A high-speed train, CRTS II slab ballastless track, and standard 32-meter girder bridge was analyzed through hybrid simulations that integrated multi-body dynamics and finite element analysis. The hybrid model included the interactions between the train, track, and bridge of the coupled system as well as track irregularity. The vibration energy of the coupled system was quantitatively investigated under various train velocities. The effects of key variables of ballastless track and bridge on energy transmission characteristics were evaluated. The studied variables included fastener stiffness, fastener damping, mortar layer stiffness, bridge cross section, and bridge damages. The results show that these variables have significant effects on vibration energy transmission, suggesting that it is important to consider these variables in the design and operation of high-speed railways.
Damage distribution and mechanical properties analysis of CRTS III slab track under uneven subgrade settlement
2023, Structures
Due to the complex geological conditions along the high-speed railway, the subgrade uneven settlement (USS) is inevitable, and the safety and stability of the railway are significantly affected. In this paper, a three-dimensional solid model of the CRTS III slab track is established. Based on the concrete damaged plasticity (CDP) model, the influence of USS on structural damage, deformation, stress, and gap is analyzed. Simultaneously, as a reinforced concrete structure, the structure reinforcement is an essential part of strengthening its tensile capacity. Consequently, the distribution of internal reinforcement is considered in detail, and the influence of reinforcement on the mechanical properties of the track structure is further explored. The results show that the base plate is the most vulnerable component under the USS, and its primary damage locations are the middle and edge of the USS and the middle track slab edge. The next component that is susceptible to damage is the self-compacting concrete, whose primary damage locations are the longitudinal outer side of the limit lug boss and the USS middle. The damage of each component increases monotonically with increasing settlement amplitude, first increasing and then decreasing with increasing wavelength, especially noting the cases of L = 15–20 m, which is the most unfavorable wavelength range for most amplitudes. The difference between the results under the CDP and linear elastic models increases with the increase in damage. The reinforcement significantly influences the value, range, and location of the structural concrete damage. The component of load-bearing stress shifts from concrete to reinforcement at severe damage locations.
Damage of CRTS III type ballastless track-32 m simply supported girder structural system under long-term deformation effects
2023, Engineering Structures
Until now, the CRTS (China’s Railway Track System) III type ballastless track-girder system has been gradually used in high-speed railway engineering. However, the effect of long-term deformation of prestressed box girders on the upper track structure is often overlooked. Given the strict requirements for track smoothness in high-speed railways, an in-depth study of the long-term deformation of the CRTS III type ballastless track-32 m simply supported girder system (girder-track system) is particularly important. In this study, a refined finite element model was established for a three-span CRTS III type ballastless track- simply supported box girder system. Based on the aid of the CEB-FIP 90 creep model and the UMAT (User-Material) subroutine, the long-term deformation calculations were investigated. Furthermore, an in-depth analysis of stress and damage of the CRTS III type ballastless track under the long-term deformation of the box girder was conducted by combining concrete damaged plasticity (CDP) and cohesive zone model (CZM) constitutive models. The numerical simulated results indicated that after four years of operation, the creep camber of the box girder in the girder-track system would reach to 3.41 mm. The maximum tensile and compressive longitudinal stresses of the base plate would reach to 0.537 MPa and 11.983 MPa, respectively. Meanwhile, the maximum tensile and compressive longitudinal stresses of the self-compacting concrete layer would reach to 0.958 MPa and 2.701 MPa, respectively. In the box girder mid-span, significant damage could be observed in the edge of the two base plates near the mid-span, with a maximum compressive damage rate of 0.164 and the maximum tensile damage rate of 0.304. The research of this study has achieved the prediction of long-term deformation in the girder-track system, providing an important basis for the reliability assessment and life prediction of the girder-track system.
Assessment of train running safety on railway bridges based on velocity-related indices under random near-fault ground motions
2023, Structures
Random analysis has emerged as the dominant approach for analyzing train-bridge coupled (TBC) systems, replacing deterministic analysis. This shift is driven by considerations of system economy and randomness. However, the seismic train running safety assessment with multiple non-Gaussian distribution parameters faces the double dilemma of low computational efficiency and inaccuracy for TBC systems. In this study, an approach is applied by the combination of the new point estimate method and moment expansion approximation (NPEM-MEA) to address this problem. Furthermore, the application of this approach is illustrated by the random dynamic responses of a three-dimensional TBC system subjected to random near-fault ground motions. Validation of the NPEM-MEA’s feasibility is conducted using the Monte Carlo method, and comparative analysis confirms the accuracy and efficiency of the method. Additionally, the influences of random near-fault ground motions are discussed based on the random dynamic responses and train running safety indices in the TBC system. The simulation results underscore the necessity of simultaneously considering the randomness of multiple parameters in seismic train running safety assessment. This methodology holds potential for safety assessments involving non-Gaussian random processes in complex systems of a similar nature.
Passenger ride comfort in subway due to new subway excavation below
2023, Tunnelling and Underground Space Technology
New tunnel excavation below existing tunnel deforms the rails inside the existing tunnel. The settlement-induced rail irregularity intensifies the wheel-rail interaction, which reduces passenger ride comfort of the existing tunnel. This research investigates the passenger ride comfort of the existing tunnel due to new tunnel excavation. A project of new twin tunnels excavation below existing triple tunnels is introduced. According to the field monitoring data, the settlement of each of the existing tunnels, although supported by different types of lining, can be fitted by the Gaussian function. Then numerical simulation is performed to study the deformation characteristics of the existing rails, which is difficult to monitor in the field. The simulation results show that the tunnel deformation can well represent the rail deformation. After that, train ride comfort is adopted to evaluate passenger comfort indirectly. The vehicle dynamic performance due to settlement-induced track irregularity is studied by a general multibody system simulation software. The results show that the vertical acceleration of the car body increases linearly with the increase of the settlement amplitude and decreases exponentially with the increase of the trough width i. When the trough width i is larger than 15 m, the vertical accelerations produced by new tunnel excavation are negligible compared to those produced by track irregularity. The settlement amplitude limits considering the passenger ride comfort in subway due to new subway excavation below are obtained.
Effect of frost heave deformation of bridge foundation on operation safety of high-speed railway
2023, Structures
Citation Excerpt :
The rail is made of steel: elastic modulus = 210 GPa, density = 7,800 kg/m3, and Poisson's ratio = 0.3. Mesh size convergence analysis is conducted to determine the appropriate mesh sizes that balance the computation accuracy and efficiency [51,52]. Firstly, the CRH2 high-speed train is established via SIMPACK and the six-span 32-m simply supported girders bridge is established in ANSYS as the substructure of the coupled model.
The frost heave deformation of the bridge foundation in seasonal frozen soil regions threatens the safe operation of high-speed trains. The first high-speed railway in extremely cold zones, the Harbin-Dalian Line, is used as the background in this study, and finite element analysis (FEA) is used to investigate the impact of freezing temperature and moisture content on the frost heave force and deformation of the bridge foundation. Furthermore, the dynamic response of the train crossing the frost heave deformation region of the bridge foundation is analyzed based on finite element (FE) and multi-body dynamics co-simulation. Conclusively, the frost heave threshold of the bridge foundation is proposed in accordance with the limit of the train’s dynamic response indicators. The results indicate that the normal frost heave stress at the bottom section of the cap is distributed in a “W” shape along the lateral direction of the cap. The magnitude of the stress at the edges of the cap and the inner hole of the pile foundation is relatively large. the frost heave deformation is negatively and positively linked with the fluctuations of temperature and moisture content, respectively. The train's vertical acceleration grows gradually as the pier's upward deformation increases, while there is no discernible relationship between the train’s lateral acceleration and the pier’s upward deformation. Additionally, variations in the train speed and the pier’s upward deformation are positively correlated with the derailment coefficient and wheel load reduction rate. To enable the high-speed railway’s operation safety, it is proposed that the deformation threshold of frost heave be 14.4 mm.

View all citing articles on Scopus

View full text

Analytical study on high-speed railway track deformation under long-term bridge deformations and interlayer degradation

Highlights

Abstract

Introduction

Section snippets

Mechanical analysis

Finite element model

Amplitudes of bridge deformations

Conclusions

Declaration of Competing Interest

Acknowledgement

NDT E Int

Eng Struct

Recent developments of high-speed railway bridges in China

Struct Infrastruct Eng

Influences of concrete creep and temperature deformation on vehicle travelling across bridge

Appl Mech Mater

A dynamic vehicle-track interaction model for predicting the track degradation process

J Infrastruct Syst

Dynamic interaction of train-bridge systems in high-speed railways: theory and applications

Gamma prediction models for long-term creep deformations of prestressed concrete bridges

J Civ Eng Manag

Elastic-plastic seismic response of CRTS II slab ballastless track system on high-speed railway bridges

Sci China Technol Sci

Interaction between continuous welded rail and long-span steel truss arch bridge of a high-speed railway under seismic action

Struct Infrastruct Eng

Effects of long-wavelength track irregularities due to thermal deformations of railway bridge on dynamic response of running train

Appl Sci

Safety and stability of light-rail train running on multispan bridges with deformation

J Bridge Eng

Effects of pier deformation on train operations within high-speed railway ballastless track–bridge systems

Transp Res Rec

3D analysis of high-speed trains moving on bridges with foundation settlements

Arch Appl Mech

In-situ test and dynamic response of a double-deck tied-arch bridge

Steel Compos Struct

Influence of long-wavelength track irregularities on the motion of a high-speed train

Veh Syst Dyn

Mapping the relationship between the structural deformation of a simply supported beam bridge and track deformation in high-speed railways

Proc Inst Mech Eng Part F J Rail Rapid Transit

Dynamic behaviors of high speed train running through subgrade-bridge transition section