High-speed Railway In China Research Articles

Arching mechanism of the slab joints in CRTSII slab track under high temperature conditions

China Railway Track System II slab track is widely applied to China high-speed railway. Under the high temperature conditions, it tends to produce different degrees of arch at the joints between prefabricated slabs, which will affect the track irregularity and safe operation of high-speed trains. In this paper, considering the buckling instability of track structure, the arching mechanism of the slab joints was investigated by establishing a 3D finite element model of the CRTSII slab track. Combined with the field investigation, the damage process of joint concrete and its effects on the arching instability were analyzed. The results show: 1) The construction of joint concrete is difficult to control on site, which leads to inferior quality compared to prefabricated slab. The worse quality of joint concrete corresponds to a smaller amplitude of temperature rise causing joints damage and a greater damage area. 2) When the amplitude of temperature rise of the slab is over 37 °C, various damage emerges in the narrow joint and the middle of wide joint, resulting in the eccentric compression. 3) The temperature gradient load will cause the propagation of interface gap between slab and CA mortar layer, which aggravates the arching instability of slab, especially when the height of gap exceeds 1.5 mm. This research is expected to provide guidance for the optimization design, maintenance and damage control of slab track.

Shattered rim and shelling of high-speed railway wheels in the very-high-cycle fatigue regime under rolling contact loading

Abstract Due to the improvement of the wear property, rolling contact fatigue including shattered rim and shelling are the main failure causes of the high-speed railway wheels. In this paper, shattered rim and shelling occurred on the service wheels of the China Railway High-speed (CRH) trains were systematically investigated. The recorded data of the last ten years CRH operation indicated that all shattered rims and shelling were detected with serving >106 km (corresponding to the fatigue life 107–109 cycles) which is very-high-cycle fatigue (VHCF). The crack initiation region of shattered rim located at the depth of 10–25 mm from the tread, while that of shelling located at the depth

Study of the Influence of Train Vibration Loading on Adjacent Damaged Tunnel

In this study, the effect of the high‐speed train vibration loading on an adjacent damaged tunnel is investigated. Three sets are established to study the effects of the different vibration loadings on the tunnel lining considering the vertical excitation force of the CRH (China Railway High‐speed) train. An expression of excitation force for the train vibration loading is applied to simulate the interaction force between wheel and rail, which is set with high‐, medium‐, and low‐frequency responses, and reflects the influences of driving comfort, additional dynamic load, and rail corrugations. The eigenvalue analysis and spring damping absorbing boundary are applied in the numerical simulation. In addition, a quantitative criterion is selected as the allowable vibration peak velocity for the cracked structure. The analysis of the vibration velocity, dynamic deformation, and acceleration of the cracking region show that the secondary lining of this damaged tunnel in set 1 basically has a higher vibration response than that in set 2 for the closer running track. The most adverse working condition with the greatest impact on the lining structure is that two CRH trains simultaneously passing through the cross section in set 3.

Collaborative Optimization of Dynamic Pricing and Seat Allocation for High-Speed Railways: An Empirical Study From China

In order to improve the high-speed trains’ service levels and increase their market shares, the Chinese high-speed railway (HSR) enterprise is reforming its ticket pricing strategy. A collaborative model that incorporates seat allocation decision into HSR dynamic pricing problem based on the revenue management theory is proposed, in which the objective is to maximize the total ticket revenue of enterprise under the constrains of price ceilings. A two-stage algorithm is developed to solve practical problems. The first stage solves the optimal price problem, and the second is to obtain the optimal seat allocation decisions. Finally, a case study based on the actual ticket data of Beijing-Shanghai HSR in China is implemented to show the effectiveness of the proposed approach, for which the results show that compared with the fixed price case, the revenue improvement ranges from 4.47% to 4.95% by using dynamic pricing strategy. Also, the case analysis shows that dynamic pricing strategy will lead to an increase in short-haul demands whereas a decrease in long-haul demands.

Fourier Series Approach for the Vibration of Euler–Bernoulli Beam under Moving Distributed Force: Application to Train Gust

The dynamic response of an Euler–Bernoulli beam under moving distributed force is studied. By decomposing the distributed force into Fourier series and extending them to semi‐infinite sine waves, the complex procedure for solving this problem is simplified to three base models, which are calculated by the modal superposition method further. The method is proved to be highly accurate and computational efficient by comparing with the finite element method. For verifying the theory and exploring the relationship between dynamic pressure due to train gust and vibration of the structure, a site test was conducted on a platform canopy located on the Beijing‐Shanghai high‐speed railway in China. The results show the theory can be used to evaluate the dynamic response of the beam structure along the trackside due to the train gust. The dynamic behavior of a 4‐span continuous steel purlin is studied when the structure is subjected to the moving pressure due to different high‐speed train passing.

Nonlinear tool traces fast tracing algorithm based on single point laser detection

There are lots of line traces on the surface of the broken ends which left in the cable cutting case crime scene along the high-speed railway in China. The line traces usually present nonlinear mor ...

Development and Application of Mechanized Matching Equipment for High-Speed Railway Tunnel Construction

Abstract Tunneling in high-speed railways is characterized by high construction standards, great construction difficulties, high safety risks and strict construction management requirements. Taking the Guiguang high-speed railway as an example, this paper analyzes several key problems that restrict construction efficiency and safety, a series of research achievements are obtained including: (1) technology of fast construction and mechanical matching for tunnel invert, (2) movable formworks for the construction of water ditch and cable channel, (3) technology of water stop with a middle buried type at lining construction, (4) technology of tunneling using micro step. The research results have been successfully applied to the construction of many high-speed railways in China. It has great significance to ensure the safety, quality, progress and cost control of the tunnel construction.

Modeling and Simulation of China Railway High-Speed Electric Multiple Units Based on Multi-Agent

Short Retraction Notice Engineering (ENG) does not meet author’s publication requirements. This article has been retracted to straighten the academic record. In making this decision the Editorial Board follows COPE's Retraction Guidelines. Aim is to promote the circulation of scientific research by offering an ideal research publication platform with due consideration of internationally accepted standards on publication ethics. The Editorial Board would like to extend its sincere apologies for any inconvenience this retraction may have caused. The full retraction notice in PDF is preceding the original paper which is marked "RETRACTED".

Volume Deformation Characteristics of Concrete Mixture during Thermal Curing Process

Expansion deformation of concrete mixture during steam curing process was a kind of unrecoverable volume expansion which would definitely affect the performance of concrete component. Because there were a few researches on expansion deformation of concrete mixture during thermal curing process, a new test method composed of constant temperature water bath, eddy current measurement sensor and data processing program was developed to measure the expansion deformation. The volume deformation characteristics of a typical concrete used for preparing track slab of China high-speed railway were investigated. Test results indicated that volume deformation of concrete mixture could be divided into 2 stages. One was rapid expansion at heating stage and another one was slow shrinkage at constant temperature stage. Besides, the addition of combination of flying ash, slag, nano-silica and nano-calcium carbonate was benefit for controlling the eventual expansion deformation during the whole thermal curing process. Study could be an important reference for heightening quality of steam-cured concrete.

A prototype fatigue test for slab track subjected to the coupling action of wheel load, temperature variation, and water erosion

Slab track is commonly used for high-speed railways in China. During its service life, the performance of the slab track may be affected by repeated wheel loading, temperature variation, and water erosion. In this study, a prototype fatigue test for the slab track was carried out during the winter season in a severely cold region of northeast China, considering the coupled effects of wheel load, temperature change, and water erosion. A loading vehicle configured with eccentric vibrator wheels was used to apply repeated wheel loading. The slab track system was heated and/or cooled to produce a temperature gradient consistent with the statistical characteristics of a real track system. Water erosion was also applied. The results show that the fatigue damage to the main structure of the slab track was less, even after 18.7 million cycles of wheel load under a severe temperature gradient. However, the cement asphalt mortar under the track slab may deteriorate rapidly from the edge and corner of the track slab when some initial damage was already present.

Investigation of track settlement and ballast degradation in the high-speed railway using a full-scale laboratory test

This paper presents a full-scale laboratory test for investigating the track settlement and ballast degradation of the ballasted track–subgrade system on the high-speed railways. The test was carried out on a full-scale test platform with a ballasted track–subgrade system constructed exactly according to the construction standards of high-speed railways in China. In this test, four million cycles of cyclic loads simulating repeated high-speed train loads with an axle load of 140 kN were applied to the ballasted track–subgrade system through a specialized loading system. The vertical displacement and settlement of the rail, the sleepers and the subgrade at various sections and depths were recorded during the test. The test results show that the settlement of the high-speed railway ballasted track is very less. A logarithmic model was proposed for predicting the settlement of the high-speed railway ballasted track by fitting the measured data. Moreover, some painted ballast samples were embedded into the tested track to investigate the ballast degradation. After the test, it was found that more than 80% of the painted ballast grains remained intact and less than 20% were degraded. Four different ballast degradation phenomena were observed: corner or edge breakage, surface scratch, surface crack and the production of fine particles. The test results indicate that the high-speed railway ballasted tracks in China are very stable and the settlement is less under long-term cyclic loads, which could significantly benefit the track geometry and the railway maintenance work.

Deformation characteristics and safety assessment of a high-speed railway induced by undercutting metro tunnel excavation

Stratum deformation (settlement) is a challenging issue in tunnel engineering, especially when construction of metro tunnels has to undercut high-speed railway. For this purpose, we used the FLAC3D software to analyze the stratum settlement characteristics of high-speed railway at different crossing angles intersected by metro tunnel, in terms of ground settlement trough, stratum slip line and irregularity of ballastless tracks. According to the evolution of the stratum settlement at different angle regions, an optimized angle is proposed for the actual project design. In order to reduce the influence of stratum settlement on the safety of high-speed railway, an approach of safety assessment is proposed for the shield engineering undercutting high-speed railway, as per Chinese specifications using numerical results and on-site conditions. A case study is conducted for the shield tunnel section crossing the Wuhan – Guangzhou High-speed Railway between the Guangzhou North Railway Station and the Huacheng Road Station, which represents the first metro tunnel project passing below a high-speed railway in China. A series of measures is taken to ensure the safe excavation of the shield tunnel and the operation of the high-speed railway. The results can provide a technical support for performing a safety evaluation between high-speed railways and metro tunnels.

Distributed cooperative control of multiple high-speed trains under a moving block system by nonlinear mapping-based feedback

Although the high-speed railways in China have been greatly advanced in the past decades with respect to expanding networks and increasing speed, a fixed block system, which separates the trains with several stationary track block sections, is utilized to guarantee the safe operation of multiple trains. A moving block system, which enables the moving authority of a high-speed train to be the real-time positioning point of its preceding one (plus some necessary safe redundant distance, of course), is under development to further make full use of the high-speed railway lines and improve the automation level by automatic train operation for high-speed trains. The aim of this paper is to design a distributed cooperative control for high-speed trains under a moving block system by giving a cooperative model with a back-fence communication topology. A nonlinear mapping-based feedback control method together with a rigorous mathematic proof for the global stability and ultimate bound of the closed-loop control systems is proposed. Comparative results are given to demonstrate the effectiveness and advantages of the proposed method.

Wind tunnel test of an aeroelastic model of a catenary system for a high-speed railway in China

Wind tunnel tests of an aeroelastic model with five masts and four spans were carried out with the design requirements of a catenary system and similarity theory to research wind characteristics. Four different forces were imposed on the contact wire and messenger wire. Turbulent and uniform flow conditions were considered in the tests. The acceleration, displacement of the hanging point and displacement of the contact wire were measured using sensors. The results are as follows: The frequency of the contact wire increases and the deflection decreases as the tension in the wire increases. The frequency of the hanging point is nearly unaffected by tension. The displacement of the hanging point can be ignored while the acceleration is influenced by tension in turbulent flow. Wind-induced responses in the turbulent flow are more intense than those in the uniform flow. The displacements in both flows in the wind and crosswind direction are large enough to receive considerable attention and should be controlled to avoid accidents in strong wind. The experiment results show the dynamic behavior of the catenary system under wind and provide a reference for the design of catenary systems.

Experimental and analytical investigation of the dynamic behavior of granular base course materials used for China's high-speed railways subjected to freeze-thaw cycles

With the rapid development of high-speed railways (HSRs) in seasonally frozen regions in China in recent years, there is an increasing need for better understanding of how the construction materials behave. In particular, the dynamic behavior of granular base course materials used for China's HSRs subjected to combined actions of cyclic loading and freeze-thaw (F-T) cycles has attracted much attention. In this study, a series of cyclic triaxial tests were performed to investigate the characteristics of granular base course materials. A number of factors including effect of F-T cycles were considered in these tests. As such, representative test results of dynamic shear stress amplitude (τ¯d), dynamic shear modulus (Gd), and damping ratio (λ) are presented and discussed. Based on the Hardin-Drnevich model, a fitting equation for determining maximum dynamic shear modulus (Gd,max) is proposed. Then, a unified normalized dynamic shear modulus (Gd/Gd,max) curve is drawn and well validated by the test results. Furthermore, equations for λ are expressed in terms of an exponential function of Gd/Gd,max. The test results show that the Gd/Gd,max curves are not completely consistent with previous studies. Overall, this study provides further insights into the dynamic behavior of granular base course materials subjected to F-T cycles.

The structural and spatial properties of the high-speed railway network in China: A complex network perspective

High-speed railway (HSR) has been one of the most important transport modes for developing cities. The development and achievement of HSR in China has attracted attention from around the world. Previous studies on HSR primarily focused on its impacts on regional development, the environment and the socio-economy. The structural and spatial properties of the HSR network have been neglected if not all. This article takes China's high-speed railway network (CHSRN) as an example and converted it into a weighted network using a P-space approach. The structural and spatial properties of CHSRN at the node and network levels are explored. The degree, strength and betweenness centralities of cities in CHSRN are calculated and analyzed. An integrated indicator based on the centrality measures is proposed to quantify the overall role of each city in CHSRN. The small-world property of CHSRN is examined, and the scale-free, spatial heterogeneity and hierarchical properties of CHSRN are examined in terms of train flow intensity. Possible factors affecting the structure and spatial properties of CHSRN are also explored.

A seat assignment model for high-speed railway ticket booking system with customer preference consideration

ABSTRACTThis paper addresses the railway revenue management problem of homogeneous seats. Within a certain period of time, multiple trains characterized by different train stop plans are alternatives to each other. For homogeneous seats, multiple fare classes are designed based on the customer preference orders of different customer types. A seat inventory control method is developed based on characteristics of the China high-speed railway (HSR). In addition, an efficient heuristic approach is proposed to solve the nonlinear integer programming model of the HSR revenue management problem. The Beijing-Shanghai HSR is taken as a case study. Numerical examples show that revenue can be increased by reasonably controlling the deterministic booking limits of different fare classes according to customer preference orders. Furthermore, our method can increase the total revenue by optimizing the resources of multiple trains with different train stop plans.

Effectiveness of CFG pile-slab structure on soft soil for supporting high-speed railway embankment

The use of cement-fly ash-gravel (CFG) pile-slab structures is a new effective technique for reducing the settlements of soft foundations in China. A comprehensive research was conducted to investigate the effectiveness of a CFG pile-slab structure-supported embankment of the Beijing-Shanghai high-speed railway in China. Firstly, an analytical method was formulated to calculate the settlements of the CFG pile-slab structure-supported embankment. Secondly, mechanical scaling laws were derived for the proposed testing plan at model scale. Model tests were conducted to quantify and to interpret the settlement distributions. Thirdly, the influence of three key factors (pile length, pile diameter, and slab thickness) for the structural form of the CFG pile-slab structure-supported embankment on the settlement distribution were studied using numerical simulations. The maximum settlements of the CFG pile-slab structure-supported embankment in optimizing the structural form were obtained using the above three research methods and then they were compared with each other. The results show that (1) the settlements obtained by the analytical method, the physical model tests, and the numerical simulations showed good concordance with each other; (2) the settlement-controlling effect of the CFG pile-slab structure was able to meet the requirements of high-speed railway construction; (3) the piles and the soil-bearing capacities of the CFG pile-slab structure-supporting embankment could be fully mobilized because of the “load re-distribution” function of the slab; and (4) the affected area of the engineering load had a depth of more than 18.75 m and a horizontal length of 7.5 m near the toe of the embankment slope.

Survey of Foreign Passengers' Satisfaction of the Service Quality of Railway Passenger Transport

In 2017, the number of foreign inbound travelers was 29.71 million, an increase of 3.6%. Foreign passengers have gradually become one of the important groups. However, there is no special study of foreign passengers’ specific demands for railway service. In this paper, we design the Chinese-English bilingual version of the “Satisfaction of Railway Passenger Service” questionnaire; apply the statistical analysis method to analyze the frequency of passengers, and the type of seats; apply the fuzzy comprehensive evaluation method to calculate the foreign passengers’ satisfaction of service links, and service projects with the highest and lowest satisfaction of foreign passengers. As special objects of railway passenger transport service, understanding foreign passengers' satisfaction of railway passenger transport service quality is able to provide a reference for China's high-speed railway to develop the strategy of "going out". In the future, the ability of China's railway passenger transport to manage safety and control quality will be "China's business card" to participate in international competition.

Finite element analysis of lateral earth pressure on sheet pile walls

Sheet pile walls providing lateral earth support are widely employed as excavation supporting systems for cutting slopes along the high-speed railway. In this study, a validated three-dimensional finite element (FE) model based on field measurements was used to explore lateral earth pressure distribution on sheet pile walls, aiming to provide guidelines and recommendations for design of the sheet pile walls. To this end, the influence of pile length, sheet's location, pile's stiffness, and soil properties on the pile performance were investigated. The results showed that the optimum pile length was about 14 m for the sheet pile walls at a China high-speed railway. The sheet's location could affect the formation of soil arching and the mechanism of earth pressure distribution. The moment of inertia of sheet pile walls was found to be effective in controlling pile displacement and earth pressure, compared to Young's modulus of the pile. Variations of soil parameters led to negligible changes in the earth pressure distribution. Furthermore, a proposed simplified straight-line form for earth pressure diagram based upon the FE analysis was developed. Compared with traditional earth pressure methods, the proposed diagram considers the sheet effect. Overall, the conducted study provided useful help toward the process of safer design and more economical sheet pile walls.