scholarly journals Dynamic Wheel-Rail Force-Based Track-Irregularity Evaluation for Ballasted Track on Serviced Railway by Adjacent Excavation

2021 ◽  
Vol 12 (1) ◽  
pp. 375
Author(s):  
Jung-Youl Choi ◽  
Dong-Ryong Park ◽  
Jee-Seung Chung ◽  
Sun-Hee Kim
Keyword(s):  
Impact Load ◽  
Field Measurements ◽  
Interaction Force ◽  
Wheel Load ◽  
Track Geometry ◽  
Railway Line ◽  
Before And After ◽  
Track Irregularity ◽  
The Impact ◽  
Track Irregularities

This study investigates a load-based, track-irregularity-analysis technique for ballasted tracks on a serviced railway line with respect to excavation work conducted in adjacent sites. A numerical analysis and field measurements (railbed-settlement-monitoring sensor, track-geometry-measurement system, wheel-load measurements) were analyzed comparatively to demonstrate the correlation between the track irregularities and the Wheel-Rail interaction force. In this way, we highlight the necessity for load-based track-irregularity-management methods. The analyzed results show that the maximum dynamic wheel load was measured in the range of approximately 10 m before and after the location where the maximum track irregularities occurred, and that even if the maintenance criteria of track irregularities were satisfied, the design dynamic wheel load could still be exceeded depending on the train speed, thus indicating that track damage can be caused by the impact load.

Comparison on General Track Spectrum for Chinese Main Railway Lines and Track Spectrum of American Railway Lines

2011 ◽  
Vol 250-253 ◽  
pp. 3822-3826 ◽  
Author(s):  
Xian Mai Chen ◽  
Xia Xin Tao ◽  
Gao Hang Cui ◽  
Fu Tong Wang
Keyword(s):  
Dynamic Performance ◽  
Dynamic Responses ◽  
Wave Band ◽  
Wheel Load ◽  
Railway Line ◽  
Acceleration Rate ◽  
Time Histories ◽  
Railway System ◽  
Dynamic Performances ◽  
Track Irregularity

The general track spectrum of Chinese main railway lines (ChinaRLS) and the track spectrum of American railway lines (AmericaRLS) are compared in terms of character of frequency domain, statistical property of time domain samples and dynamic performance. That the wavelength range of the ChinaRLS, which is characterized by the three levels according to the class of railway line, is less than AmericaRLS at common wave band of 1~50m is calculated. Simultaneously, the mean square values of two kinds of track spectra are provided at the detrimental wave bands of 5~10m, 10~20m, and so on. The time-histories of ChinaRLS and AmericaRLS are simulated according to the trigonometric method, and the digital statistical nature of simulated time samples is analyzed. With inputting the two kinds of time-histories into the vehicle-railway system, the comparative analysis of the two kinds of dynamic performances for ChinaRLS and AmericaRLS is done in terms of car body acceleration, rate of wheel load reduction, wheel/rail force, and the dynamic responses of track structure. The result shows that ChinaRLS can characterize the feature of the Chinese track irregularity better than AmericaRLS, the track irregularity with the ChinaRLS of 200km/h is superior to the AmericaRLS, and the track irregularity with the ChinaRLS of 160km/h corresponds to with the sixth of AmericaRLS.

Relationships Between Wheel/Rail Surface Impact Loadings and Correspondingly Transmitted Tie/Ballast Impact Pressures for Revenue Train Operations

2018 ◽  
Author(s):  
Travis J. Watts ◽  
Jerry G. Rose ◽  
Ethan J. Russell
Keyword(s):  
Test Section ◽  
Impact Load ◽  
Peak Force ◽  
Pressure Measurements ◽  
Track Geometry ◽  
Impact Forces ◽  
Interfacial Pressure ◽  
Degradation Rates ◽  
The Stability ◽  
The Impact

A series of specially designed granular material pressure cells were precisely positioned directly below the rail at the tie/ballast interface to measure typical interfacial pressures exerted by revenue freight trains. These vertical pressures were compared to the recorded wheel/rail nominal and peak forces for the same trains traversing nearby mainline wheel impact load detectors (WILDs). The cells were imbedded within the bottom of new wood ties so that the surfaces of the pressure cells were even with the bottoms of the ties and the underlying ballast. The cells were inserted below consecutive rail seats of one rail to record pressures for a complete wheel rotation. The stability and tightness of the ballast support influenced the magnitudes and consistencies of the recorded ballast pressures. Considerable effort was required to provide consistent ballast conditions for the instrumented ties and adjacent undisturbed transition ties. Norfolk Southern (NS) crews surfaced and tamped through the test section and adjacent approach ties. This effort along with normal accruing train traffic subsequently resulted in reasonably consistent pressure measurements throughout the test section. The impact ratio (impact factor) and peak force values recorded by the WILDs compared favorably with the resulting magnitudes of the transferred pressures at the tie/ballast interface. High peak force and high impact ratio WILD readings indicate the presence of wheel imperfections that increase nominal forces at the rail/wheel interface. The resulting increased dynamic impact forces can contribute to higher degradation rates for the track component materials and more rapid degradation rates of the track geometry. The paper contains comparative WILD force measurements and tie/ballast interfacial pressure measurements for loaded and empty trains. Typical tie/ballast pressures for locomotives and loaded freight cars ranges from 20 to 30 psi (140 to 210 kPa) for smooth wheels producing negligible impacts. The effect of increased wheel/rail impacts and peak force values on the correspondingly transmitted pressures at the tie/ballast interface is significant, with increased pressures of several orders of magnitude compared to nominal impact forces from wheels.

scholarly journals Reinforced Concrete Plates under Impact Load—Damage Quantification

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4554
Author(s):  
Marcus Hering ◽  
Franz Bracklow ◽  
Silke Scheerer ◽  
Manfred Curbach
Keyword(s):  
Reinforced Concrete ◽  
Impact Load ◽  
Experimental Conditions ◽  
Steel Reinforced Concrete ◽  
Before And After ◽  
Concrete Plates ◽  
The One ◽  
Objective Description ◽  
The Impact ◽  
Impact Experiments

A large number of impact experiments have been carried out at the Technische Universität Dresden in recent years in several research projects. The focus was on reinforced concrete plates on the one hand and on subsequently strengthened reinforced concrete plates on the other hand. Based on these investigations, two fundamental tasks arose: (1) finding an objective description of the damage of components made of steel reinforced concrete that had previously been subjected to an impact load and (2) quantification of the effect of a subsequently applied strengthening layer. In this paper we will focus on both. At first, the experimental conditions and program as well as the used drop tower facility at the Otto Mohr Laboratory of the Technische Universität Dresden are briefly explained. In the summary presentation of the main test results, the focus is on the observed component damage. Based on the observations, an approach for a damage description is presented. To define global damage, the stiffness of the investigated structural components before and after the impact event is used. At the end of the paper, the potential of the method, but also gaps in knowledge and research needs are discussed.

scholarly journals Train Derailment Process Analysis on Heavy Haul Railway Bridge under Ship Impact

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2122
Author(s):  
Kai Gong ◽  
Linya Liu ◽  
Cuiying Yu ◽  
Chen Wang
Keyword(s):  
Impact Load ◽  
Lateral Displacement ◽  
Process Analysis ◽  
Great Influence ◽  
Reduction Rate ◽  
Relative Displacement ◽  
Wheel Load ◽  
Train Derailment ◽  
Spatial Vibration ◽  
The Impact

In order to research train derailment law under ship impact, the spatial vibration calculation model of a freight train-track-bridge (FTTB) system is used to establish the vibration model of the FTTB system under ship impact. Meanwhile, the calculation method of a train derailment process under ship impact is proposed based on the random analysis method of train derailment energy. Further, the train derailment process on a bridge under ship impact is calculated, and the variation law of the FTTB system spatial vibration response under different impact loads and speeds is analyzed. The results show that the ship impact load has a great influence on wheel lift value. When the impact load is greater than 15 MN, the wheel derails more easily. With the increase of impact load, the derailment coefficient, wheel load reduction rate, and lateral relative displacement of bogie and rail, the lateral displacement of the bridge increases significantly, but the limits of them make it difficult to determine whether the wheel has derailed. The lateral relative displacement of the bogie and rail considering the safety factor is calculated at the moment of derailment, which is taken as the early warning threshold of train derailment. The above conclusions can provide a reference for controlling train safety under ship impact.

scholarly journals Permissible Values of the Dynamic Impact of the Rolling Stock on the Railway Track in the Case of Axle Load Increase

2021 ◽  
pp. 15-23
Author(s):  
О. M Patlasov ◽  
Y. M Fedorenko
Keyword(s):  
Dynamic Effect ◽  
Field Measurements ◽  
Experimental Tests ◽  
Railway Track ◽  
Rolling Stock ◽  
Actual State ◽  
Dynamic Force ◽  
Dynamic Impact ◽  
Railway Line ◽  
The Impact

Purpose. The study is aimed at determining experimentally the values of the parameters characterizing the dynamic effect of rolling stock on the railway track, substantiating the maximum permissible (limiting) values. Methodology. To investigate the interaction between the track and the rolling stock, the devices to record various physical processes were installed on the experimental sections. The devices were installed in 8 sections along the outer railway line. To establish the actual state of the track, field measurements were carried out in accordance with the Program and research methodology. Findings. According to the results of experimental tests of the impact on the track, it was revealed that the average vertical loads, and, accordingly, the average vertical deformations, under the cars with an axle load of up to 25 tf/axle are higher than that under the cars with an axle load of up to 23.5 tf/axle by 8 percent. The maximum vertical loads under the cars with an axle load of 25 tf/axle exceeded the average loads by 10.0 tf, and under the cars with an axle load of up to 23.5 tf/axle exceeded the average values by 12.8 tf. During the tests, no cars were found in which the vertical dynamic force exceeds 20 tf, and the horizontal force exceeds 10 tf. Therefore, the norms of permissible dynamic impact can be taken in accordance with the Regulations on Preventive Maintenance and Repair Track Work on the Railways of Ukraine. Originality. The authors conducted a study to assess the dynamic characteristics of the interaction of track and rolling stock, in particular the stresses in the edges of the rail base, vertical and horizontal forces from the wheels of rolling stock. Practical value. On the basis of the results obtained, it is possible to estimate the permissible values of the dynamic effect of the rolling stock on the railway track to substantiate the need to change the standards for the material consumption of the track superstructure and labor. In turn, this will make it possible to plan the repair and track periods more economically and according to the actual indicators of the state of the track superstructure.

Multiple Regression Analysis of the Impact of Track Geometry on Wheel-Rail Forces

2012 ◽  
Author(s):  
Wei Huang ◽  
Yan Liu ◽  
Jon Preston-Thomas
Keyword(s):  
Regression Analysis ◽  
Multiple Regression Analysis ◽  
Multiple Regression ◽  
Field Tests ◽  
Load Ratio ◽  
Computer Models ◽  
Wheel Load ◽  
Track Geometry ◽  
Safety Standards ◽  
The Impact

One of the fundamental keys to improving track safety standards is to establish a strong correlation between track geometry variations and wheel-rail force parameters that are indicators of vehicle-track safety performance. In this study, wheel-rail forces were collected during field tests of a loaded lumber car and an empty tank car. Computer models of the two tested freight cars were built, and the models were calibrated using field test results. The computer models were then used to evaluate the impact of varying track geometry parameters on track safety using the maximum single wheel L/V ratio, maximum truck side L/V ratio, and minimum vertical wheel load ratio. It was confirmed again that the correlations between these force parameters and any individual geometry parameter were weak. With further investigation, it was found that much better correlation can be achieved using multiple regression techniques to define each wheel-rail force parameter as a function of all track geometry parameters combined together. Expressions of the maximum truck side L/V ratio, maximum single wheel L/V ratio, and minimum vertical wheel load ratio were obtained as functions of curvature, cross level, alignment, gauge, and cant deficiency using multiple regression analysis.

Wu Guang High-Speed Rail Track Irregularity Power Spectrum Analysis

2014 ◽  
Vol 638-640 ◽  
pp. 1224-1228 ◽  
Author(s):  
Ji Yang Li ◽  
Lin Ya Liu ◽  
Dong Hua Kou
Keyword(s):  
Power Spectrum ◽  
High Speed ◽  
Railway Track ◽  
High Speed Rail ◽  
Track Geometry ◽  
Railway Line ◽  
Spectrum Density ◽  
Track Irregularity ◽  
Parameter Values ◽  
Geometry Inspection

Irregularity is the locomotive and the main excitation source of vibration, is directly related to the smooth running of the train, safety and comfort, is to control the maximum operating speed of the train one of the main factors. The statistic specimen was collected by track geometry inspection car from Wuhan-Guangzhou high-speed rail. Based on the stationarity test of the specimen, Fast Fourier Transform (FFT) method was used to evaluate the spectrum of the whole specimen space. The power spectrum density (PSD) and related functions of track irregularity were obtained by MATLAB program. We analyzed it by comparing the fitting curve of the national speed lines and fitting curve of Qinhuangdao-Shenyang dedicated passenger railway line, by comparison, the Wuhan-Guangzhou high-speed railway track irregularity is much better than the national speed lines and Qinhuangdao-Shenyang dedicated passenger railway line. The parameter values of PSD fitting curve for track irregularity are obtained by the nonlinear curve-fitting algorithm in the least-squares sense, which has referencing value to maintenance high-speed rail.

scholarly journals Fracture Characteristics and Geometric Fractal of Damaged Sandstone under Impact Load

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Hao Hu ◽  
Qiangqiang Zheng ◽  
Xin Gao ◽  
Bing Cheng ◽  
Qianqian Wang ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Impact Load ◽  
Reduction Rate ◽  
Average Diameter ◽  
Rock Block ◽  
Damage Factor ◽  
Hopkinson Pressure Bar ◽  
Fracture Characteristics ◽  
Before And After ◽  
The Impact

Before the rock mass in the engineering is broken under load, it is usually in a state of varying degrees of damage. Aiming at the fracture characteristics of damaged sandstone under impact load, this paper adopts a method of the cyclic static load to cause the sandstone specimens to have varying degrees of damage. Then, the wave velocity of sandstone before and after the damage is measured using the nonmetallic acoustic velocimeter, and the change rule of damage factor is analyzed. Finally, the split Hopkinson pressure bar (SHPB) is used to test the impact dynamics of sandstone with different damage degrees. The broken rock block is screened by a vibrating screen, and the crushing characteristics are analyzed. The results show that not only the damage factor of damaged sandstone but the growth rate increases, with the raising upper limit of stress. Under the impact load of the same incident energy, the fragmentation degree of the damaged sandstone increases with the increase of the upper stress limit, while the average diameter of the broken rock block decreases gradually, and the reduction rate increases first and then decreases.

Investigation of Relationship between Train Speed and Bolted Rail Joint Fatigue Life using Finite Element Analysis

2018 ◽  
Vol 2672 (10) ◽  
pp. 85-95 ◽  
Author(s):  
Hao Yin ◽  
Yu Qian ◽  
J. Riley Edwards ◽  
Kaijun Zhu
Keyword(s):  
Finite Element ◽  
Contact Force ◽  
Impact Load ◽  
Wheel Load ◽  
Joint Area ◽  
Train Speed ◽  
Stress Propagation ◽  
Speed Restrictions ◽  
The Impact ◽  
The Relationship

Reducing the allowable operating speed or imposing temporary speed restrictions are common practices to prevent further damage to rail track when defects are detected related to certain track components. However, the speeds chosen for restricted operation are typically based on past experience without considering the magnitude of the impact load around the rail joints. Due to the discontinuity of geometry and track stiffness at the bolted rail joints, an impact load always exists. Thus, slower speeds may not necessarily reduce the stresses at the critical locations around the rail joint area to a safe level. Previously, the relationship between speed and the impact load around the rail joints has not been thoroughly investigated. Recent research performed at the University of Illinois at Urbana-Champaign (UIUC) has focused on investigating the rail response to load at the joint area. A finite element model (FEM) with the capability of simulating a moving wheel load has been developed to better understand the stress propagation at the joint area under different loading scenarios and track structures. This study investigated the relationship between train speed and impact load and corresponding stress propagation around the rail joints to better understand the effectiveness of speed restrictions for bolted joint track. Preliminary results from this study indicate that the contact force at the wheel–rail interface would not change monotonically with the changing train speed. In other words, when train speed is reduced, the maximum contact force at the wheel–rail interface may not necessarily reduce commensurately.

Strategic Role of Zakat in Multidimensional Quality of Life in Sijunjung, Indonesia

2018 ◽  
Vol 15 (1) ◽  
pp. 55-72
Author(s):  
Herlin Hamimi ◽  
Abdul Ghafar Ismail ◽  
Muhammad Hasbi Zaenal
Keyword(s):  
Quality Of Life ◽  
Positive Impact ◽  
Wealth Distribution ◽  
Absolute Poverty ◽  
Before And After ◽  
The Status ◽  
Being There ◽  
The Impact

Zakat is one of the five pillars of Islam which has a function of faith, social and economic functions. Muslims who can pay zakat are required to give at least 2.5 per cent of their wealth. The problem of poverty prevalent in disadvantaged regions because of the difficulty of access to information and communication led to a gap that is so high in wealth and resources. The instrument of zakat provides a paradigm in the achievement of equitable wealth distribution and healthy circulation. Zakat potentially offers a better life and improves the quality of human being. There is a human quality improvement not only in economic terms but also in spiritual terms such as improving religiousity. This study aims to examine the role of zakat to alleviate humanitarian issues in disadvantaged regions such as Sijunjung, one of zakat beneficiaries and impoverished areas in Indonesia. The researcher attempted a Cibest method to capture the impact of zakat beneficiaries before and after becoming a member of Zakat Community Development (ZCD) Program in material and spiritual value. The overall analysis shows that zakat has a positive impact on disadvantaged regions development and enhance the quality of life of the community. There is an improvement in the average of mustahik household incomes after becoming a member of ZCD Program. Cibest model demonstrates that material, spiritual, and absolute poverty index decreased by 10, 5, and 6 per cent. Meanwhile, the welfare index is increased by 21 per cent. These findings have significant implications for developing the quality of life in disadvantaged regions in Sijunjung. Therefore, zakat is one of the instruments to change the status of disadvantaged areas to be equivalent to other areas.

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