scholarly journals Response of railway track system on poroelastic half-space soil medium subjected to a moving train load

2008 ◽  
Vol 45 (18-19) ◽  
pp. 5015-5034 ◽  
Author(s):  
Yuanqiang Cai ◽  
Honglei Sun ◽  
Changjie Xu
Keyword(s):  
Half Space ◽  
Railway Track ◽  
Soil Medium ◽  
Track System ◽  
Moving Train

scholarly journals Multi-Factor Modeling Method of the Load Sharing Ratio under Moving Train Loads

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yong Liu ◽  
Shiyu Zhang ◽  
Yang Jin ◽  
Yuxiang Song
Keyword(s):  
Prediction Model ◽  
Load Sharing ◽  
Railway Track ◽  
Loading Method ◽  
Vibration Prediction ◽  
Track System ◽  
Environmental Vibration ◽  
Factor Modeling ◽  
The Impact ◽  
Moving Train

In railway engineering, the load sharing ratio (LSR) is the ratio of the rail seat load (RSL) to the axle load, which is affected by many factors. The LSR can be used in the design and analysis of railway track structures as well as in the research of predicting the dynamic influence of railway tunnels and the environment. The “static loading method” commonly used to study the LSR does not conform to reality; using it, it is difficult to obtain a complete LSR curve, limiting its application. Besides, there is currently a lack of LSR prediction methods considering the impact of multiple factors. Therefore, this paper proposes a “moving loading method” for investigating the LSR under moving train excitation, verified to be rational by comparing with the experimental results. At the same time, a procedure for establishing the LSR multi-factor prediction model is put forward, namely, we (1) determine the LSR function form and the fitting algorithm; (2) perform parameter sensitivity analysis to determine the main influencing parameters of the LSR function; and (3) design a quadratic regression orthogonal test to obtain the prediction formula of the LSR function coefficients. Once establishing the prediction model for a type of train-track system, the LSR of similar systems can be calculated by adjusting the main parameters of the model. Shijiazhuang Metro Line 1 using the A-type vehicle and the monolithic trackbed is taken as a case study to develop a corresponding LSR multi-factor prediction model by the moving loading method and the procedure mentioned above. The results indicate that the proposed method performs well and can be adopted to enhance the accuracy of track design or tunnel and environmental vibration prediction.

Semianalytical Solution for Dynamic Responses of Railway Track System on Unsaturated Poroelastic Half-Space Subjected to Moving Trainload

2021 ◽  
Vol 21 (3) ◽  
pp. 04021016
Author(s):  
Chuxuan Tang ◽  
Zheng Lu ◽  
Hailin Yao ◽  
Shuan Guo ◽  
Xiangqun Huang ◽  
...  
Keyword(s):  
Half Space ◽  
Dynamic Responses ◽  
Railway Track ◽  
Track System

IMPORTANCE OF NONLINEARITY OF TRACK SUPPORT SYSTEM IN MODELING OF RAILWAY TRACK DYNAMICS

2013 ◽  
Vol 13 (01) ◽  
pp. 1350008 ◽  
Author(s):  
J. SADEGHI ◽  
M. FESHARAKI
Keyword(s):  
Support System ◽  
Field Tests ◽  
Field Investigation ◽  
Dynamic Responses ◽  
Railway Track ◽  
Nonlinear Properties ◽  
Railway Tracks ◽  
Track Dynamics ◽  
Track System ◽  
Axle Loads

Attention is drawn to the fact that the recent increase in axle loads, speed and traffic volume in railway tracks, as well as concerns over passengers' riding comfort and safety have resulted in fresh challenges that are needed to be addressed. These challenges can only be successfully tackled with a more accurate modeling of the dynamic behavior of railway tracks. Although a significant amount of research involving mathematical modeling of railway track dynamics has been conducted in the last two decades, the nonlinearity of track support systems has not been given sufficient attention. This paper is concerned with the effect of nonlinearity of the support sub-layers on the dynamic responses of the railway track. To this end, a railway track model that considers the nonlinear properties of the track sub-layers is developed. Then, a field investigation into the dynamic responses of the railway track system under moving trains is conducted. The effect of the nonlinearity properties of the track support system on the track responses is investigated by comparing the results obtained by the numerical model, with or without consideration of track support nonlinearity, with those from the field tests. It is illustrated that consideration of the nonlinear properties of the track support system improves the accuracy of the calculated responses by a factor of three. It is also shown that the train axle loads and track accumulative loading have a significant effect on the nonlinearity of the track support system and, as a result, on the modeling of track responses.

Finite Element Analysis of a Fishplate Rail Joint in Extreme Environment Condition

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Sunil Kumar Sharma ◽  
Jaesun Lee
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Extreme Environment ◽  
High Rate ◽  
Railway Track ◽  
Element Analysis ◽  
Track System ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Railways are very efficient mode of transportation. Speed limits of the railways and loads they carry are increasing rapidly. Due to some advantages, the insulated rail joints are still the part of a rail-track system. However, a high rate of failure of joints puts the railway track at risk. Therefore, a detailed study of these joints is required. In this paper, a three-dimensional finite element model of rail-fishplate joint is created using Abaqus - a finite element method-based software. Stresses in fishplate and bolts due to wheel impact are analysed by coupling implicit and explicit methods. It is found that bolts are a critical part of a joint due to stresses and vibrations to which they are subjected. The large number of stresses and vibration can result into loosening of bolts.

scholarly journals Application of low-order potential solutions to higher-order vertical traction boundary problems in an elastic half-space

2018 ◽  
Vol 5 (5) ◽  
pp. 180203 ◽  
Author(s):  
Adam G. Taylor ◽  
Jae H. Chung
Keyword(s):  
Boundary Condition ◽  
Half Space ◽  
Granular Media ◽  
Elastic Half Space ◽  
Higher Order ◽  
Classical Solutions ◽  
Internal Stresses ◽  
Normal Surface ◽  
Soil Medium ◽  
Traction Distribution

New solutions of potential functions for the bilinear vertical traction boundary condition are derived and presented. The discretization and interpolation of higher-order tractions and the superposition of the bilinear solutions provide a method of forming approximate and continuous solutions for the equilibrium state of a homogeneous and isotropic elastic half-space subjected to arbitrary normal surface tractions. Past experimental measurements of contact pressure distributions in granular media are reviewed in conjunction with the application of the proposed solution method to analysis of elastic settlement in shallow foundations. A numerical example is presented for an empirical ‘saddle-shaped’ traction distribution at the contact interface between a rigid square footing and a supporting soil medium. Non-dimensional soil resistance is computed as the reciprocal of normalized surface displacements under this empirical traction boundary condition, and the resulting internal stresses are compared to classical solutions to uniform traction boundary conditions.

Moving element analysis of discretely supported high-speed rail systems

2017 ◽  
Vol 232 (3) ◽  
pp. 783-797 ◽  
Author(s):  
Jian Dai ◽  
Kok Keng Ang ◽  
Minh Thi Tran ◽  
Van Hai Luong ◽  
Dongqi Jiang
Keyword(s):  
High Speed ◽  
Railway Track ◽  
High Speed Train ◽  
Element Analysis ◽  
High Speed Rail ◽  
Mass System ◽  
Rail System ◽  
Rail Systems ◽  
Track System ◽  
The Difference

In this paper, a computational scheme in conjunction with the moving element method has been proposed to investigate the dynamic response of a high-speed rail system in which the discrete sleepers on the subgrade support the railway track. The track foundation is modeled as a beam supported by uniformly spaced discrete spring-damper units. The high-speed train is modeled as a moving sprung-mass system that travels over the track. The effect of the stiffness of the discrete supports, train speed, and railhead roughness on the dynamic behavior of the train–track system has been investigated. As a comparison, the response of a continuously supported high-speed rail system that uses a foundation stiffness equivalent to that of a discretely supported track has been obtained. The difference in results between the “equivalent” continuously supported and the discretely supported high-speed rails has been compared and discussed. In general, the study found that a high-speed train that travels over a discretely supported track produces more severe vibrations than that travels over a continuously supported track of equivalent foundation stiffness.

Mathematical Modeling for Longitudinal Displacement of a Straight Continuously Welded Railway Track and its Numerical Implementation

2011 ◽  
Vol 462-463 ◽  
pp. 801-806 ◽  
Author(s):  
Abreeza Manap
Keyword(s):  
Mathematical Model ◽  
Computer Software ◽  
Railway Track ◽  
Track Length ◽  
Longitudinal Displacement ◽  
Track System ◽  
Displacement Pattern ◽  
Longitudinal Flexibility ◽  
Displacement Patterns ◽  
The Mathematical Model

A mathematical model of the longitudinal flexibility of a continuously welded railway track and the methodology for the analysis of the longitudinal displacement of rails under the effects of passing trains is developed to investigate the longitudinal behavior of rails. The purpose of this analysis is to explore the changes of longitudinal stress distribution in the rails due to mechanical loading applied by a travelling train. A half track system is used to derive the equations required to obtain the magnitude of deflection and force of rails and these values are scaled to produce the displacement pattern using the method of superposition. The mathematical model is translated into MATLAB and validation of the program is verified through comparisons of displacement patterns generated by a computer software LONGIN. Analysis of a straight track due to train braking was performed over a track length of 1000 m. The longitudinal displacement obtained showed that maximum longitudinal displacement occur in the middle of the track at the distance of 570 m which is in direct agreement with the published result.

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