Beijing-Tianjin High-speed Railway Research Articles

Land subsidence along the Beijing-Tianjin high-speed railway before and after the South-to-North water diversion project with multi-source monitoring datasets

The development of land subsidence has seriously affected the safe operation of Beijing-Tianjin high-speed railway. The South-to-North Water Diversion Project Central Route (SNWDP-CR) was officially put into operation in December 2014. It has changed the water supply pattern in Beijing and provided conditions for reducing groundwater exploitation and controlling land subsidence. In this paper, the time-series interferometric data, in situ monitoring data of recent 20 years and the basic geological datasets are combined to compare and analyze the changes of groundwater level, land subsidence and the main subsidence layers along the Beijing-Tianjin high-speed railway before and after the SNWDP-CR. The effects of the environment of Quaternary sedimentary, groundwater exploitation and soil deformation of different lithology on land subsidence along the high-speed railway under the background of new water conditions are revealed. The main conclusions are as follows: 1) The serious land subsidence area along the Beijing-Tianjin high-speed railway always concentrated in the section of DK11-DK23. After the operation of SNWDP-CR, the land subsidence along the railway generally showed a slowing trend. The maximum subsidence rate was reduced from 80 mm/yr to 49 mm/yr. The length of subsidence rate that more than 50 mm/yr of the section was reduced from 8.0 km to 0 km. 2) The groundwater level of different aquifer groups along the Beijing-Tianjin high-speed railway rose and declined before and after the SNWDP-CR. in eastern part of the plain, the groundwater level of each aquifer group has changed from a continuous decline (range 0.13–1.82 m) to a gradual rise (range 0.45–1.87 m) since 2017. However, in the southeast of the plain, the groundwater level still showed a continuous decline trend, with an average annual decline of 1.2–1.8 m. 3) From 2006 to 2019, the subsidence of the first, second and third compression layer group along the railway accounted for 2.71%, 28.29% and 69%, respectively. The third compression layer group (monitoring layer 94–182 m) had the largest subsidence proportion and was the main subsidence layer. 4) The land subsidence along the Beijing-Tianjin high-speed railway is controlled by the basement structure. The difference of groundwater exploitation intensity led to differences in the spatial distribution of land subsidence along the railway. The subsidence of the soil layer below the bearing layer (about 50 m) of the high-speed railway pile foundation exhibited the characteristics of viscoplastic or viscoelastic plasticity deformation. This section of strata is a key layer that needs to be considered for land subsidence control along the Beijing-Tianjin high-speed railway in the future.

A train timetable rescheduling approach based on multi-train tracking optimization of high-speed railways

PurposeThis paper aims to propose a train timetable rescheduling (TTR) approach from the perspective of multi-train tracking optimization based on the mutual spatiotemporal information in the high-speed railway signaling system.Design/methodology/approachFirstly, a single-train trajectory optimization (STTO) model is constructed based on train dynamics and operating conditions. The train kinematics parameters, including acceleration, speed and time at each position, are calculated to predict the arrival times in the train timetable. A STTO algorithm is developed to optimize a single-train time-efficient driving strategy. Then, a TTR approach based on multi-train tracking optimization (TTR-MTTO) is proposed with mutual information. The constraints of temporary speed restriction (TSR) and end of authority are decoupled to calculate the tracking trajectory of the backward tracking train. The multi-train trajectories at each position are optimized to generate a time-efficient train timetable.FindingsThe numerical experiment is performed on the Beijing-Tianjin high-speed railway line and CR400AF. The STTO algorithm predicts the train’s planned arrival time to calculate the total train delay (TTD). As for the TSR scenario, the proposed TTR-MTTO can reduce TTD by 60.60% compared with the traditional TTR approach with dispatchers’ experience. Moreover, TTR-MTTO can optimize a time-efficient train timetable to help dispatchers reschedule trains more reasonably.Originality/valueWith the cooperative relationship and mutual information between train rescheduling and control, the proposed TTR-MTTO approach can automatically generate a time-efficient train timetable to reduce the total train delay and the work intensity of dispatchers.

Dynamic performance evaluation of ballastless track in high-speed railways under subgrade differential settlement

Ballastless tracks are widely used to provide high rail smoothness in high-speed railways. However, the differential settlement inevitably develops in the subgrade soil, which poses a great threat to the track performance and riding quality via the train-rail dynamic interaction. Since the ballastless tracks are extremely difficult to repair during the maintenance window, it is quite necessary to carry out preventive maintenance to keep the track in good conditions. In order to relate the railway performance with the profiles of subgrade differential settlement, a three-dimensional train-ballastless track-subgrade model was developed incorporating 64 combinations of settlement wavelengths and amplitudes at the roadbed surface. The numerical results were first verified with the measured velocity responses at the concrete base in the Beijing-Tianjin high-speed railway. Then the dynamic responses of the train-track system caused by subgrade differential settlement were analyzed, including the dynamic displacement of train wheels and track structure, wheel-rail interaction forces and car body accelerations. Railway performance was further evaluated as track degradation, lower riding comfort and risk of train safety based on these indicators at different settlement profiles. Results show that increasing settlement amplitudes result in stronger dynamic wheel-rail interaction and vibration of car body. However, critical settlement wavelengths of 10 m and 10–20 m are found to exist where the wheel-rail interaction forces and accelerations of the car body reach their peak values, respectively. It also reveals that the current design limits on the subgrade settlement of high-speed railways are infeasible for infrastructure managers to evaluate the railway status or organize the maintenance works. Moreover, the wheel-rail interaction forces are more credible to determine the railway status than the car body acceleration.

Analysis of the Impact of High-speed Railway on the Upgrade of Consumption Structure

In 2008, with the opening of the Beijing-Tianjin High-speed Railway, China entered an era of rapid development of high-speed railways. The operation of high-speed railways in the past decade has had many effects on the economic development of the surrounding areas. In this paper, the panel data of 9 prefecture-level cities in Fujian Province from 2008 to 2018, the first high-speed railway in China to achieve "city-city connectivity", are analyzed by regression analysis. The results verify that the operation of the highspeed rail has a significant positive effect on the upgrade of the local consumption structure and the actual per capita disposable income and actual per capita GDP that affect residents' consumption.

Investigating land subsidence and its causes along Beijing high-speed railway using multi-platform InSAR and a maximum entropy model

Beijing-Tianjin High Speed Railway is the first high-speed railway in China. The Beijing section of it runs through areas affected by subsidence which threaten its safe operation. This study develops a new time series fusion method based on the minimum gradient difference of a fitting curve to produce time series subsidence along this section. Through blending Envisat ASAR and TerrSAR-X time series, the InSAR-derived subsidence and its spatial–temporal development was analyzed along the railway. The relationship between subsidence and its causes was then explored using a maximum entropy model. The study reveals that: (1) The subsidence dynamics identified using the new fusion method agrees with the ground deformation measurements; (2) The sections of most severe subsidence occur between kilometer point KP 11 and KP 21; and (3) The main hydrogeological factors affecting subsidence are the compressible deposit thickness and the groundwater level in the second confined aquifer. The new fusion method proposed improves the accuracy and reliability of subsidence time series. It extends the time span of subsidence monitoring. The approach is mainly applicable to areas with significant vertical deformation, and is particularly suitable for integrating multi-platform data with overlapping in time or with a short time gap.

Research on electromagnetic transient process in articulated split-phase insulator of high-speed railway considering viaduct's electrical coupling

Summary In single-phase alternating current (AC) traction power supply system, to balance 3-phase load of power system, each phase of electricity is used in rotation. Based on the 7-section articulated split-phase insulator of China Beijing-Tianjin high-speed railway line, different electromagnetic transient processes are deeply analyzed considering pantograph arc and viaduct's electrical coupling in this paper. First, based on the lumped parameter model, the process of high-speed train passing the articulated split-phase region, concluding the upper viaduct part and the lower viaduct part, is deeply studied. Second, through state-space technique, 4 independent electromagnetic transient processes in articulated split-phase region of high-speed railway are derived and analyzed thoroughly considering the impact of pantograph arc and viaduct. Finally, the integral transient process is accurately simulated and analyzed by ATP-EMTP software under several circumstances, such as different topologies, initial phase and phase difference of feeders, and specific suppression overvoltage measures. The independent and integral comparison results illustrate that the coupled viaduct can lead to the more complex topologies and electromagnetic transient processes. Also, the coupled viaduct can play a significant topology discharge and pantograph overvoltage suppression role for the high-speed train passing articulated split-phase region.

Non-stationary channel characterization for high-speed railway under viaduct scenarios

Non-stationary properties based on Markov chains are provided to characterize the wireless propagation mechanism of high-speed railway (HSR) under viaduct scenarios. This Markov modeling method reveals the temporal statistical behaviors of the persistence process corresponding to resolvable multipath components. Using the channel measurement data on Beijing–Tianjin HSR at 2.35 GHz, the steady-state probability matrices and the transition probability matrices of Markov chains are specified. The non-stationary channel parameters are informative for the link-level simulation and can be used for prototype verification for non-stationary HSR channels. In addition, we propose and investigate the concepts of the medium-scale fading entropy and lifetime, which quantitatively describe the degrees of uncertainty and stability, respectively. Furthermore, our provided models are compared with the experimental results by means of the Kullback–Leibler (KL) distance. It shows that the simulated results match the measured data very well.

Modeling and Algorithms of the Crew Scheduling Problem on High-speed Railway Lines

The crew scheduling plan on high-speed railway is usually represented as set covering problem, and can be solved by selecting a set of crew routes in a large number of feasible crew routes. It is usually difficult to find the optimal solution for this problem, because the number of the train lines is large and the generation of crew routes are restricted by many regulations. By analyzing the characteristic of crew scheduling plan on high-speed railway in China, this dissertation divides the process for working out the plan into two phases. Since the cost of the crew scheduling plan is determined at the first phase, this dissertation mainly focuses on the modeling of this sub problem. The effectiveness of the algorithm is testified by a real world numerical example of Beijing-Tianjin high-speed railway.

High-speed train–track–bridge dynamic interactions – Part II: experimental validation and engineering application

Experimental validation is a precondition for dynamic simulation of high-speed train–track–bridge interaction system to be applied to railway engineering in the field. The paper first presents an onsite experiment of the train–track–bridge interaction dynamics carried out on the Beijing–Tianjin high-speed railway, and then the experimental results are used to validate the train–track–bridge interaction simulation software (TTBSIM). There is a good correlation between the calculated results and the measured data. As a case study, the Yellow River Bridge in the Beijing–Shanghai high-speed railway is studied, from modelling of the bridge structure to evaluating the dynamic performance of the train–track–bridge interaction system under the CRH3 EMU passing through at speeds of 250–375 km/h. The calculated and measured results are also compared in the case of such a large steel bridge under high-speed moving train, demonstrating the effectiveness of the TTBSIM simulation for dynamic evaluation of complex bridge structures in high-speed railways.

Pantograph and catenary system with double pantographs for high-speed trains at 350 km/h or higher

The paper is aimed at developing an optimized design of the pantograph and catenary system with double pantographs at a speed of 350 km/h for the Wuhan-Guangzhou high-speed railway. First, the pantograph and catenary system for the Beijing-Tianjin high-speed railway was analyzed to verify whether its design objective could be fulfilled. It shows that the system is not able to satisfy the requirement of a sustainable running speed of 350 km/h. Then a new scheme for the pantograph and catenary system is proposed through optimization and renovation of the structure and parameters of the pantograph and catenary system, including the suspension type of the catenary, tension of the contact wire, and space between two pantographs. Finally, the dynamic performance of the new system was verified by simulation and line testing. The results show that the new scheme of the pantograph and catenary system for the Wuhan-Guangzhou high-speed railway is acceptable, in which the steady contact between the rear pantograph and the catenary at the space of 200 m can be maintained to ensure the current-collection quality. A current collection with double pantographs at a speed of 350 km/h or higher can be achieved.

Impact of ground subsidence on the Beijing–Tianjin high-speed railway as mapped by radar interferometry

The construction of the Beijing–Tianjin high-speed railway line started in July 2005. The railway has been completed and opened to traffic in August 2008, just before the Beijing Olympic Games. The 113 km railway costing 13.3 billion Yuan (US $1.5 billion) is the country's first high-standard passenger rail. It is also believed to be the pilot project of a massive high-speed rail network in China. The train shuttles passengers between the cities in just half an hour, 45 minutes shorter than the usual travel time. The train is designed to go 200 km/h, but can reach speeds of 350 km/h. The current railway is under pressure, handling 25.55 million passengers each year. The new passenger rail line is expected to handle 32 million passengers from 2008 and 54 million passengers in 2015. Both Tianjin and Beijing have been suffering from ground subsidence due to groundwater extraction. This study focuses on mapping the impact of such subsidence on the Beijing–Tianjin high-speed railway using differential radar interferometry. Both persistent scatterer interferometric synthetic aperture radar (PSInSAR) and differential InSAR (DInSAR) techniques are used to analyse SAR data collected by ENVISAT ASAR and ALOS PALSAR sensors. The results are further analysed in GIS and compared with reported ground survey results.