Analysing the effect of principal stress rotation on railway track settlement by discrete element method

Géotechnique ◽  
2020 ◽  
Vol 70 (9) ◽  
pp. 803-821 ◽  
Author(s):  
Xuecheng Bian ◽  
Wei Li ◽  
Yu Qian ◽  
Erol Tutumluer
Keyword(s):  
Discrete Element Method ◽  
Principal Stress ◽  
Discrete Element ◽  
Railway Track ◽  
Principal Stress Rotation ◽  
Stress Rotation ◽  
Element Method

Experimental and Numerical Study of Railway Ballast Compactness during Tamping Process

2013 ◽  
Vol 690-693 ◽  
pp. 2730-2733
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Bo Yan ◽  
Jun Feng Sun
Keyword(s):  
Discrete Element Method ◽  
Numerical Study ◽  
Discrete Element ◽  
Railway Track ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Before And After ◽  
Filling Method ◽  
Element Method

Railway ballast tamping operations is employed in order to restore the geometry of railway track distorted by train traffics. The main goal is to compact the stone ballast under the sleepers supporting the railway squeezing and vibrations. The ballast compactness is the most direct index for evaluating the effect of tamping operation. This paper presents an experimental method used to detect the railway ballast compactness before and after tamping operation based on water-filling method, and creates a discrete element analysis model of railway ballast which analyzes the change of ballast compactness before and after tamping operation based on discrete element method. The simulation results are very similar with experimental results, which verify that the discrete element method is an effective method to evaluate the change of railway ballast compactness during tamping process.

Suitability of empirical equations for estimating permanent settlement of railway foundation materials subject to cyclic loading with principal stress rotation

2020 ◽  
Author(s):  
Anna Mamou ◽  
William Powrie ◽  
C.R.I. Clayton ◽  
Jeffrey A. Priest
Keyword(s):  
Principal Stress ◽  
Laboratory Tests ◽  
Linear Regression Analysis ◽  
Clay Content ◽  
Railway Track ◽  
Estimation Accuracy ◽  
Empirical Equations ◽  
Principal Stress Rotation ◽  
Stress Rotation ◽  
Undrained Conditions

This paper uses the results of a series of laboratory tests with cyclic principal stress rotation to assess the suitability of a number of empirical equations for estimating the development of plastic settlements in railway track foundations. The laboratory tests were carried out on three sand-clay mixes representative of railway track foundation materials, in both free-to-drain and undrained conditions. The results of a non-linear regression analysis demonstrate that the drainage conditions are the key factor affecting the estimation accuracy of the models, with the clay content playing a secondary role. The correlation coefficient was generally higher in free-to-drain than in undrained conditions, and reduced slightly with increasing clay content.

scholarly journals Discrete Element Method Simulation of Railway Ballast Compactness During Tamping Process

2013 ◽  
Vol 7 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Taoyong Zhou ◽  
Bin Hu ◽  
Junfeng Sun ◽  
Zhongtian Liu
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Railway Track ◽  
Analysis Model ◽  
Railway Ballast ◽  
Simulation Data ◽  
Element Analysis ◽  
Discrete Element Method Simulation ◽  
Change Trend ◽  
Element Method

Railway ballast tamping operation is employed in order to restore the geometry of railway track distorted by train traffics. In this paper, based on analysis of tamping principle, the discrete element analysis model of railway ballast is created using the discrete element method, numerical simulations are performed to study the change of railway ballast compactness during tamping process. This paper presents the motion trend of stone ballasts as the change trend of railway ballast compactness in qualitative analysis, and the distance between stone ballast and sleeper as the change index of railway ballast compactness in quantitative analysis. By comparing simulation data of different vibration frequencies, an optimal vibration frequency is obtained. The simulation results accord with the actual industrial tamping operation, which verifies that the discrete element method is an effective method to evaluate the change of railway ballast compactness during tamping process.

Discrete Element Method Simulation of Mesomechanics of Railway Ballast during Tamping Process

2013 ◽  
Vol 690-693 ◽  
pp. 2726-2729 ◽  
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Bo Yan ◽  
Ping Xu
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Interaction Force ◽  
Practical Experience ◽  
Field Trials ◽  
Railway Track ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Element Method

Railway ballast tamping operations is employed in order to restore the geometry of railway track distorted by train traffics. The selection of tamping parameter is usually dependent on field trials and practical experience, for lack of theoretical basis. This paper creates discrete element analysis model of railway ballast using the discrete element method, the numerical simulations are carried out to study the mesomechanics of railway ballast during tamping process. We focus on the change of railway ballast compactness and stone ballast interaction force during tamping process. The present study can be helpful for the analysis of the internal mechanism of ballast compaction during tamping process.

Discrete element method to model cracking for two layer systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 101-108
Author(s):  
Daniel Varney ◽  
Douglas Bousfield
Keyword(s):  
Discrete Element Method ◽  
Flexural Modulus ◽  
Single Layer ◽  
Discrete Element ◽  
Flexural Stress ◽  
Layer System ◽  
Three Point Bending ◽  
Moving Force ◽  
Coating Layers ◽  
Element Method

Cracking at the fold is a serious issue for many grades of coated paper and coated board. Some recent work has suggested methods to minimize this problem by using two or more coating layers of different properties. A discrete element method (DEM) has been used to model deformation events for single layer coating systems such as in-plain and out-of-plain tension, three-point bending, and a novel moving force picking simulation, but nothing has been reported related to multiple coating layers. In this paper, a DEM model has been expanded to predict the three-point bending response of a two-layer system. The main factors evaluated include the use of different binder systems in each layer and the ratio of the bottom and top layer weights. As in the past, the properties of the binder and the binder concentration are input parameters. The model can predict crack formation that is a function of these two sets of factors. In addition, the model can predict the flexural modulus, the maximum flexural stress, and the strain-at-failure. The predictions are qualitatively compared with experimental results reported in the literature.

Sign in / Sign up

Export Citation Format

Share Document