scholarly journals Performance Analysis of Prefabricated Steel-Spring Floating-Slab Track and Its Application to Urban Express Rail Transit

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Xudong Huang ◽  
Ping Li ◽  
Xinwei Luo ◽  
Liang Ling ◽  
Abdulmumin Ahmed Shuaibu ◽  
...  
Keyword(s):  
Reduction Rate ◽  
Vertical Displacement ◽  
Vibration Response ◽  
Lateral Acceleration ◽  
Vehicle Body ◽  
Scale Model ◽  
Rail Transit ◽  
Vertical Force ◽  
Steel Spring ◽  
Slab Track

The aim of the research is the design of prefabricated steel-spring floating-slab track to be applied in urban express rail transit systems. Using a developed vehicle-track dynamic-coupling equation for steel-spring floating-slab track, the effects of length, thickness, vertical damping, and use of side-mounted isolators on the floating-slab track were investigated experimentally using full-scale model and under different working conditions. The finding of the study revealed the following: (1) The prefabricated steel-spring floating-slab track can be applied to urban express rail transit, because it meets the requirements of high-speed transit while efficiently reducing noise. (2) The floating-slab track’s stability slightly increases with the increase of its length and thickness. As thickness increases, vertical displacement of the rail increases slightly, and lateral stability increases, thereby slightly improving the vehicle’s running stability. (3) When the intercity electric multiple-unit train travels along the prefabricated steel-spring floating-slab-track bed at different speeds, the wheel-axle lateral force, wheel-rail vertical force, the derailment coefficient, the wheel-weight reduction rate, and the lateral acceleration of the vehicle body are all less than the specified limits of Chinese code, thus fully meeting the safety requirements of train operation. (4) Appropriately increasing the vertical-support damping of the floating slab can improve the vehicle’s vertical dynamic performance, reduce the vertical displacement of the rail, and lower the vibration response of the floating slab. (5) Adding side-mounted vibration isolators at the joint of the floating slab could greatly improve the stability of the floating slab itself and appropriately reduce the vehicle’s vertical vibration response. Due to the optimization and establishment of relevant factors influencing the performance of prefabricated steel-string floating-slab track achieved in the study, the results obtained are particularly useful for setting safety, comfort, and stability requirements of the floating slab.

scholarly journals Numerical analysis of influence of different track structures on vibration response of subway

2020 ◽  
Vol 24 (3 Part A) ◽  
pp. 1537-1543 ◽  
Author(s):  
Xin Zhou
Keyword(s):  
Vertical Displacement ◽  
Vibration Response ◽  
Dynamic Equations ◽  
Vehicle Body ◽  
Subway Tunnel ◽  
Vehicle Model ◽  
Middle Point ◽  
Evaluation Indexes ◽  
Coupling Dynamic ◽  
Rail Structure

Taking Beijing metro line 5 as the research vehicle model, the influence of different track structure on subway vibration is analyzed. According to the coupling dynamic equations of vehicle rail, the coupling dynamic equations of vehicle body models under integrated rail bed, plate rail bed and floating plate rail structure are established, respectively, and the vibration response of vehicle body models under three kinds of rail structure is calculated. The evaluation indexes of dynamic characteristics of rail coupling are analyzed. The analysis results show that with the increase of subway speed, the vertical displacement and acceleration between the vehicle and the middle point of the track gradually increase, and the vibration response of the fourth wheel to the maximum wheel-rail force also gradually increases. With the increase of the buried depth of subway tunnel, the maximum vertical displacement and ground motion acceleration of the three tracks gradually decrease, which indicates that this method can accurately analyze the vibration response of subway under different track structures.

scholarly journals Experimental study on dynamic response of model shield tunnel induced by moving-axle loads of subway train

2018 ◽  
Vol 14 (10) ◽  
pp. 155014771880278
Author(s):  
Mengxi Zhang ◽  
Xiaoqing Zhang ◽  
Lei Li ◽  
Chengyu Hong
Keyword(s):  
Time History ◽  
Vertical Displacement ◽  
Wheel Speed ◽  
Dynamic Responses ◽  
Scale Model ◽  
Shield Tunnel ◽  
Laboratory Model ◽  
Cover Depth ◽  
Axle Loads ◽  
Subway Train

A new testing method was introduced to apply moving-axle loads of a subway train on a track structure. In order to investigate the dynamic responses of the shield tunnel subjected to moving-axle loads, a series of laboratory model tests were conducted in a 1/40 scale model tunnel. The influences of the axle load, the wheel speed, and the cover depth of the shield tunnel on the vertical displacement and acceleration of the lining were presented and discussed. Parametric studies revealed that the vertical displacement–time history of the lining presents a “W” shape due to the combined action of two axles of a bogie. The peak value of the vertical displacement increased with the axle load linearly, while it decreased with the increase in the cover depth. Moreover, response time of the displacement decreased with the increase in the wheel speed, but the peak values remained stable at the same level. Finally, a three-dimensional dynamic finite element model was adopted to simulate the movement of the axle loads and calculate the responses of the lining. The numerical results analysis agrees well with experimental results.

Full scale model tests on slab track constructed on embankment

2012 ◽  
pp. 547-553 ◽  
Author(s):  
Jiang Hongguang ◽  
Bian Xuecheng ◽  
Chen Yunmin ◽  
Jiang Jianqun
Keyword(s):  
Model Tests ◽  
Full Scale ◽  
Scale Model ◽  
Slab Track

scholarly journals Modelling and Sensitivity Analysis of Influencing Parameters in Displacement of Dynamic Bodies

2021 ◽  
Vol 06 (05) ◽  
Author(s):  
Yokesh K.S ◽  
Keyword(s):  
Dynamic Characteristics ◽  
Vertical Displacement ◽  
Suspension System ◽  
Damping Coefficient ◽  
Vehicle Body ◽  
Dominant Factor ◽  
Spring Stiffness ◽  
Variation Of Parameters ◽  
Important Challenge ◽  
Influencing Parameters

The mathematical modelling in relation to the Six-degree freedom system of train suspension is developed and simulated for their dynamic characteristics. The important challenge in the suspension system is vertical displacement obtained from the vehicle body. To reduce vertical displacement, an analysis of the model is done by variation of parameters such as stiffness of spring and damping coefficient. The model has been created by deriving the equations of a system using Newton’s law. The developed model has the potential to analyse the dynamic characteristics of the suspension system for both displacement of the vehicle body and displacement of the wheel. The outcome of this research revealed that Secondary spring stiffness is the most dominant factor to influence the displacement of the vehicle body; Primary damping coefficient is the most dominant factor to influence displacement of the wheel.

Finite Element Analysis of Rail-End Bolt Hole and Fillet Stress on Bolted Rail Joints

2017 ◽  
Vol 2607 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Kaijun Zhu ◽  
Yu Qian ◽  
J. Riley Edwards ◽  
Bassem O. Andrawes
Keyword(s):  
Finite Element ◽  
Vertical Displacement ◽  
Rail Transit ◽  
Rail Transportation ◽  
Element Analysis ◽  
Transit System ◽  
Transit Systems ◽  
Service Failures ◽  
The University ◽  
Continuously Welded Rail

A rail joint typically is one of the weakest elements of a track superstructure, primarily because of discontinuities in its geometric and mechanical properties and the high-impact loads induced by these discontinuities. The development of continuously welded rail has significantly reduced the number of rail joints, but many bolted joints remain installed in rail transit systems. Because of the unique loading environment of a rail transit system (especially high-frequency, high-repetition loads), defects related to bolted rail joints (e.g., joint bar failures, bolt hole cracks, and cracks in the upper fillet) continue to cause service failures and can pose derailment risks. Recent research in the Rail Transportation and Engineering Center at the University of Illinois at Urbana–Champaign has focused on investigating crack initiation in the bolt hole and fillet areas of bolted rail joints. Stress distribution was investigated at the rail-end bolt hole and upper fillet areas of standard, longer, and thicker joint bars under static loading conditions. Numerical simulations were organized into a comprehensive parametric analysis performed with finite element modeling. Preliminary results indicated that the longer joint bar performed similarly to the standard joint bar but the thicker joint bar reduced rail vertical displacement and rail upper fillet stresses compared with the standard joint bar. However, the thicker joint bar also may generate higher stresses at the rail-end bolt hole. Additionally, joint bar performance was dependent on the rail profile and bolt hole location.

Analysis of the influence of train load characteristics on the water damage of slab tracks

2018 ◽  
Vol 232 (7) ◽  
pp. 2024-2038 ◽  
Author(s):  
Shihao Cao ◽  
Rongshan Yang ◽  
Shijie Deng ◽  
Jiali Li ◽  
Jiaduo Xu ◽  
...  
Keyword(s):  
Hydrodynamic Pressure ◽  
Second Derivative ◽  
Vertical Force ◽  
Distribution Characteristics ◽  
Wheel Load ◽  
Slab Track ◽  
Loading Method ◽  
Loading Function ◽  
Water Damage ◽  
Superimposed Effect

High-speed train load is one of the main factors that causes the failure of a slab track and is also the direct cause for producing water pressure in the cracks. Hence, choosing the right loading method is the key to analyze the water damage of slab tracks. In order to identify the distribution characteristics of the vertical force acting on the slab track, the analytic expression of fastener load was derived, and the field test was conducted to verify the theoretical model. According to the distribution characteristics of fastener load and the area of crack filled with water, the loading method was presented to analyze the water damage of slab tracks, and the influence of loading characteristics on the hydrodynamic pressure and crack propagation was analyzed. The results show that the distribution of fastener load in the main affected zone approximately accords with the Gaussian distribution under the single wheel load. When under the action of double wheels, the superimposed effect makes the second derivative of the loading function to increase by 99.93%. The superimposed effect of three or more wheels is less than 1% and can be ignored. Considering that the hydrodynamic pressure is highly sensitive to the second derivative of loading function, the load applied on the track slab should be in the form of a bogie, and different loads should be applied step by step based on the time series. The distribution of hydrodynamic pressure along the crack is approximately equal to the cubic polynomial, and the pressure peak appears at the crack tip. Also, the pressure is proportional to the square of the running speed of the train. In the region with abundant rainwater and a poor drainage system, reducing the train speed and taking timely measures such as grouting can effectively reduce the water damage of slab tracks.

Mutual influence of long-span urban highway tunnel and rail transit construction

2021 ◽  
pp. 1-15
Author(s):  
Honglin Yu ◽  
Shiyang Liu ◽  
Chun Zheng ◽  
Yun Li ◽  
Jie Liu
Keyword(s):  
Mutual Influence ◽  
Vertical Displacement ◽  
Relative Displacement ◽  
Urban Rail Transit ◽  
Rail Transit ◽  
Railway Line ◽  
Long Span ◽  
Highway Tunnel ◽  
Urban Rail ◽  
Secondary Lining

In order to analyze the mutual influence between the long-span highway tunnel and urban rail transit tunnel that is constructed at proximity, this paper established 3D finite element models based on Chongqing Zengjiayan Tunnel and the Metro Railway Line 9 and Line 10 projects to calculate and analyze the secondary lining stress, distribution and change law of deformation of Zengjiayan Tunnel and the Metro Railway Line Tunnel. The results show that: (1) The main risk of the Zengjiayan Tunnel is that the tunnel body might displace in the excavation and the surrounding rock stress could possibly change. The forces undertaken by the main structure of the cross-section are calculated and analyzed based on the shallow buried tunnel. Accordingly, the horizontal and vertical displacement limit and relative displacement meet the relevant specification; (2) Zengjiayan Tunnel over the lobby of Liyuchi Station, a transitional station of Line 9 and Line 10. The main risk is the displacement of the transitional channel in the excavation and changes in the stress on surrounding rocks, but the risk of self-structure excavation and support is under control.

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