Numerical analysis of high‑speed railway slab tracks using calibrated and validated 3D time‑domain modelling

Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance frequency.In this paper,the elastic performance of a novel slab trackform for high-speed railways is investigated using three-dimensional finite element modelling in Abaqus.It is then compared to the performance of a ballasted track.First,slab and ballasted track models are developed to replicate the full-scale testing of track sections.Once the models are calibrated with the experimental results,the novel slab model is developed and compared against the calibrated slab track results.The slab and ballasted track models are then extended to create linear dynamic models,considering the track geodynamics,and simulating train passages at various speeds,for which the Ledsgard documented case was used to validate the models.Trains travelling at low and high speeds are analysed to investigate the track deflections and the wave propagation in the soil,considering the issues associated with critical speeds.Various train loading methods are discussed,and the most practical approach is retained and described.Moreover,correlations are made between the geotechnical parameters of modern high-speed rail and conventional standards.It is found that considering the same ground condition,the slab track deflections are considerably smaller than those of the ballasted track at high speeds,while they show similar behaviour at low speeds.

New technologies for high-risk tunnel construction in GuiyangGuangzhou high-speed railway

Based on the construction of high risk tunnels in Guiguang-Guangzhou high-speed railway, several new technologies were developed for high-risk tunnel con- struction. First, an integrated advanced geological predic- tion was developed for tunneling in karst area. Then, a new system of ventilation by involving the dedusting technol- ogy was proposed and used in the field, which received a good air quality. Finally, a method to minimize the dis- tance between the working face and the invert installation was proposed by optimizing the invert installation and adopting the micro bench method. Applying the method to the project obtained an excellent result. The achievement obtained for this study would be able to provide a valuable reference to similar projects in the future.

New Stage for Railway Reform and Development

1. Review of railway work in 1996 The year 1996 was an important year for China’s railways in facing a historic turning point—— committing itself to a programme of structural re-

New Railways in China

Beijing-Kowloon Railway The Beijing-Kowloon Railway (Beijing-Shenzhen linking up with Kowloon) runs from north Beijing, through Bazhou, Hengshui, Liaocheng, Heze, Shangqou, Fuyang, Macheng, Jiujiang, Nancheng, Xiangtang, Jian, Ganzhou, Longchuan to Shenzhen, linking up with Kowloon. It is 2, 538 km in length, consisting of a normal railway of 2, 370 km, a secondary railway of 77 km from Tianjin to Bazhou and another secondary railway of 91 km from Macheng to Wuhan. It runs through nine provinces and municipalities——Beijing, Tianjin, Hebei, Shangdong, Henan, Anhui, Hubei, Jiangxi and Guangdong. It will be built by the end of 1995, and begin trial operation in 1996. It has an

Systematic Research and Innovation Practice on New Concepts of Construction for Xiong'an Railway Station

As the first major transport infirastructure in Xiong'an New Area,Beijing-Xiong an Intercity Railway is an important step for China State Railway Group Co.A Ltd.to quickly implement the major strategic plan of CPC Central Committee and the State Council.for the establishment of Xiong'an New Area.Xiong'an Station with double-floor spacious waiting areas and the wonderfiul integration of overpass and station building is the first modern integrated transport hub of this kind in China.Based on the characteristics of Xiong'an Station and in the light of the relevant new theories,methods and technologies,systematic studies and innovative practices on the new concept of building up a"well-connected,filly-integrated,environmen-frindly,passenger-oriented,economically-efficient,uurally-rich,intelligent and convenient"passenger station are carried oul,which achieve good results of application and help accumulate valuable experiences for the construction of passenger stations of Chinese high-speed railways in the new era.

Ensure Rights and Interests of Passengers——On new rules of railway accident investigation and reporting

China has issued new regu- lations on the rescue and investigation of railway acci- dents, which came into forcein September 2007.

The West Railway Station:A New Goat to Beijing

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Dynamic behavior of new cutting subgrade structure of expensive soil under train loads coupling with service environment

Expansive soil is sensitive to dry and wet environment change. And the volume deformation and inflation pressure of expansive soil may induce to cause the deformation failure of roadbed or many other adverse effects. Aimed at a high-speed railway engineering practice in the newly built Yun-Gui high-speed railway expansive soil section in China, indoor vibration test on a full-scaled new cutting subgrade model is carried out. Based on the established track-subgrade-foundation of expansive soil system dynamic model test platform, dynamic behavior of new cutting subgrade structure under train loads coupling with extreme service environment(dry, raining, and groundwater level rising) is analyzed comparatively. The results show that the subgrade dynamic response is significantly influenced by service conditions and the dynamic response of subgrade gradually becomes stable with the increasing vibration times under various service environment conditions. The vertical dynamic soil stress is related with the depth in an approximate exponential function, and the curves of vertical dynamic soil stress present a "Z" shape distribution along transverse distance. The peak value of dynamic soil stress appears below the rail, and it increases more obviously near the roadbed surface. However, the peak value of dynamic soil stress is little affected outside 5.0 m of center line. The vibration velocity and acceleration are in a quadratic curve with an increase in depth, and the raining and groundwater level rising increase both the vibration velocity and the acceleration. The vertical deformations at different depths are differently affected by service environment in roadbed. The deformation of roadbed increases sharply when the water gets in the foundation of expansive soil, and more than 60% of the total deformation of roadbed occurs in expansive soil foundation. The laid waterproofing and drainage structure layer, which weakens the dynamic stress and improves the track regularity, presents a positive effect on the control deformation of roadbed surface. An improved empirical formula is then proposed to predict the dynamic stress of ballasted tracks subgrade of expansive soil.

Implementing New Requirements of Passenger Station Construction and Building Excellent Passenger Station

In line with the new concept of building up a“well-connected,fullyi integrated,environment-friendlypassenger-oriented,economically-efficient,culturally-rich,intelligent and convenient”railway station and the construction requirements of"elaborate,fine and exquisite construction of excellent passenger stations" put forward by China State Railway Group Co.Ltd.,design optimization and innovation are carried out in the construction of Nantongxi Railway Station and Pingtan Station in the aspects offunctional layout,decoration style,cultural enhancement,construction materials to be used,details treatment of the station buildings and the use of photoelectric technology,focusing on the consideration and research for furrther enhancing cultural confidence,deeply integrating into the regional features,inheriting historical context,innovating artistic expression,trying diversified integration,and exploring the use of science and technology in the contexl 0f the new era,and thus devoting to the construction of railway passenger stations in the new era which will meet the growing needs of the people for a better life.

Research on Practice of Excellent Railway Passenger Station Construction and High-quality Development

Taking the construction of excellent passenger stations in Beijing-Tianjin-AHebei region as the research object,the paper discusses the implementation of the new concept of building up“well-connected fully-integrated,envioment-friendlyy passenger-oriented,economically-eficient,culturally-rich intelligent and convenient”railway passenger stations It then strives to analyze the connotation of an excellent railway passenger station,the construction and management methods,and the innovation of the working mechanism in the new era.It offers thoughts and methods for promoting the highquality development in the practice of construction for innovative development of excellent passenger stations.

Research on Management Innovation and Development for Railway Passenger Station Construction

Based on the general high-quality development requirements for railway construction in the new era,combined with the new concept of railway passenger stations of China State Railway Group Co.Ltd,namely"being well-connected,fully-integrated,environmeni-friendlypassenger-oriented,economically-efficient,culturally-rich,intelligent and convenient"and aiming at the construction of exemplary passenger station projects,this paper summarizes the construction experience in construction,decoration furnishing culture and art expression of railway passenger stations,proposes the working patterns of formulating the implementation plans of exemplary railway passenger station projects and the expert reviews in innovative way studies and forms 6 special-subject designs such as for colorshape,space,environment,art and culture,as wellas the specific design requirements for 13 key areas including waiting hall entrance and exit corridor;VIP room,etc.,and summarizes and puts forward the construction management system of railway passenger stations in the new era,so as to ensure the expected exemplary project quality of railway passenger stations.

Path selection and mechanism innovation of improving railway energy efficiency–from foreign experience and Chinese practice

Purpose–Under the dual pressure of resources and environment,many countries have focused on the role of railways in promoting low-carbon development of integrated transportation and of even the whole society.This paper aims to provide a comprehensive study on methods to improve railway energy efficiency in other national railways and achievements made by China’s railways in the past practice,and then to propose ways in which in the future China’s railways could rationally select the path of improving energy efficiency regarding the needs of the nation’s ever-shifting development and carry out the re-engineering for mechanism innovation in energy conservation and emission reduction process.Design/methodology/approach–This paper first studies other national railways that have tried to promote the improvement of railway energy efficiency by the ways of technology,management and structural reconstruction to reduce energy consumption and carbon emissions.Among them,the effect of structural energy conservation and emission reduction has become more prominent.It has become the main energy conservation and emission reduction measure adopted by foreign railway sectors.The practice of energy conservation and emission reduction of railways in various countries has tended to shift from a technical level to a structural one.Findings–Key aspects in improving energy efficiency include re-optimization of energy structure,reinnovation of energy-saving technologies and optimization of transportation organization.Path selection includes continuing to promote electrified railway construction,increasing the use of new and renewable energy sources,and promoting the reform of railway transportation organizations.Originality/value–This paper provides further challenges and research directions in the proposed area and has referential value for the methodologies,approaches for practice in a Chinese context.To achieve the expected goals,relevant supporting policies and measures need to be formulated,including actively guiding integrated transportation toward railway-oriented development,promoting innovation in energy-saving and emission reduction mechanisms and strengthening policy incentives,focusing on improving the energy efficiency of railways through market behavior.At the same time,it is necessary to pay attention to new phenomena in the railway industry for track and analysis.

Rapid profiling rock mass quality underneath tunnel face for Sichuan-Xizang Railway

The Sichuan-Xizang Railway is a global challenge,surpassing other known railway projects in terms of geological and topographical complexity.This paper presents an approach for rapidly profiling rock mass quality underneath tunnel face for the ongoing construction of the Sichuan-Xizang Railway.It adopts the time-series method and carries out the quantitative analysis of the rock mass quality using the depth-series measurement-while-drilling(MWD)data associated with drilling of blastholes.A tunnel face with 15 blastholes is examined for illustration.The results include identification of the boundary of homogeneous geomaterial by plotting the blasthole depth against the net drilling time,as well as quantification of rock mass quality through the recalculation of the new specific energy.The new specific energy profile is compared and highly consistent with laboratory test,manual logging and tunnel seismic prediction results.This consistency can enhance the blasthole pattern design and facilitate the dynamic determination of charge placement and amount.This paper highlights the importance of digital monitoring during blasthole drilling for rapidly profiling rock mass quality underneath and ahead of tunnel face.It upgrades the MWD technique for rapid profiling rock mass quality in drilling and blasting tunnels.

Deep learning based Doppler frequency offset estimation for 5G-NR downlink in HSR scenario

In the fifth-generation new radio(5G-NR) high-speed railway(HSR) downlink,a deep learning(DL) based Doppler frequency offset(DFO) estimation scheme is proposed by using the back propagation neural network(BPNN).The proposed method mainly includes pre-training,training,and estimation phases,where the pre-training and training belong to the off-line stage,and the estimation is the online stage.To reduce the performance loss caused by the random initialization,the pre-training method is employed to acquire a desirable initialization,which is used as the initial parameters of the training phase.Moreover,the initial DFO estimation is used as input along with the received pilots to further improve the estimation accuracy.Different from the training phase,the initial DFO estimation in pre-training phase is obtained by the data and pilot symbols.Simulation results show that the mean squared error(MSE) performance of the proposed method is better than those of the available algorithms,and it has acceptable computational complexity.

Technical Research and Innovative Practice of Excellent Passenger Stations Design

The key points and strategies of the design of railway passenger stations in the new era are described.The distinctive features,design innovation points and design elements of high-quality projects of large transport hubs are analyzed through dissecting two cases of completed projects,ie Xiong'an Station and Beijing Chaoyang Station.In the light of the general requirements for passenger station construction of China State Railway Group Co.Lid the paper elaborates the development and application trends of railway passenger stations ofthe new erain terms of environmental protection,energy saving,economic efficiency,culture,convenient circulation and intelligence.In addition,new concepts,new technologies and new materials are actively developed and key technologies of the design of iconic excellent passenger stations of the new era are explored and summarized.

The New Railway Station

THE Beijing West Railway Station has been completed and opened recently. As the biggest passenger station in China and the beginning of the BeijJng-Kowloon Line, it holds several firsts Jn the Chinese railway construction history. Beijing West Railway Station is the biggest, has the greatest amount of investment, the most advanced technical equipment and functions. The main hall is 102 meters high and is also one of the most magnificent buildings in Beijing, featuring the Chinese national style.

Mechanical performance analysis and stiffness test of a new type of suspension bridge

A new type of suspension bridge is proposed based on the gravity stiffness principle.Compared with a conventional suspension bridge,the proposed bridge adds rigid webs and cross braces.The rigid webs connect the main cable and main girder to form a truss that can improve the bending stiffness of the bridge.The cross braces connect the main cables to form a closed space truss structure that can improve the torsional stiffness of the bridge.The rigid webs and cross braces are installed after the construction of a conventional suspension bridge is completed to resist different loads with different structural forms.A new type of railway suspension bridge with a span of 340 m and a highway suspension bridge with a span of 1020 m were designed and analysed using the finite element method.The stress,deflection of the girders,unbalanced forces of the main towers,and natural frequencies were compared with those of conventional suspension bridges.A stiffness test was carried out on the new type of suspension bridge with a small span,and the results were compared with those for a conventional bridge.The results showed that the new suspension bridge had a better performance than the conventional suspension bridge.