Construction Of Subway Research Articles

Overview and Analysis of Ground Subsidence along China’s Urban Subway Network Based on Synthetic Aperture Radar Interferometry

Deformation along a subway rail network is related to the safe operation of the subway and the stability of construction facilities on the surface, making long-term deformation monitoring imperative. Long-term monitoring of surface deformation along the subway network and statistical analysis of the overall deformation situation are lacking in China. Therefore, targeting 35 Chinese cities whose subway mileage exceeds 50 km, we extracted their surface deformation along subway networks between 2018 and 2022, using spaceborne synthetic aperture radar (SAR) interferometry (InSAR) technology and Sentinel-1 satellite data. We verified the results with the continuous global navigation satellite system (GNSS) stations’ data and found that the root mean square error (RMSE) of the InSAR results was 3.75 mm/year. Statistical analysis showed that ground subsidence along the subways was more prominent in Beijing, Tianjin, and other areas in the North China Plain, namely Kunming (which is dominated by karst landforms), as well as Shanghai, Guangzhou, Qingdao, and other coastal cities. In addition, an analysis revealed that the severity of surface subsidence correlated positively with a city’s gross domestic product (GDP) with a Pearson correlation of 0.787, since the higher the GDP, the more frequent the construction and maintenance of subway, and the more commuters there are, which in turn exacerbates the disturbance to the surface. Additionally, the type of land cover also affects the ground deformation. Our findings provide a reference for constructing, operating, and maintaining the urban subway systems in China.

Research on wheel-rail noise in rail corrugation road of urban rail transit

As an efficient, fast, green and environmentally friendly means of transportation, subway vehicles account for the largest proportion of urban rail transit, and in large and medium-sized cities, the construction of subway is still in rapid development, but with the subway noise radiation problem, subway noise plagued by passengers, related operators and residents along the subway. In this study, the finite element analysis software ABAQUS is used to establish the coupled dynamics model of subway B-type vehicle-rail, and the acoustic radiation characteristics of wheels and rails are calculated based on the FE-BE and FE-SEA method, respectively, with the aim of analyzing the effects of different wavelength and depth parameters on the dynamics of vehicle response and wheel-rail noise radiation pattern when the vehicle is running on the rail corrugation road. The results of the study show that the effect of rail corrugation parameters on the power level of wheel and rail sound radiation is more significant in the low-frequency range, and the wheel-rail noise is mainly radiated by the wheel in the low-frequency range, while in the high-frequency range, it is mainly radiated by the rail.

Japan’s Science and Technology Diplomacy: Society 5.0 and its International Projection

Japan is the third largest economy on the planet but lacks coercive capacity due to Article 9 of its Constitution, which prevents it from having an army and declaring war. This means that it can only rely on persuasion to influence the international sphere and achieve its political objectives. One of the tools it has for this purpose is public diplomacy, which is diplomacy exercised through non-traditional means such as communication, art and culture. One branch of public diplomacy is science and technology diplomacy (S&T Diplomacy), which consists of collaboration in these areas with other nations to strengthen their international projection, as well as the dissemination of scientific knowledge and technology transfer between nations. S&T diplomacy has become a major focus for Japan of its diplomatic action since it launched the Society 5.0 project in 2016, which sought to revolutionize Japan’s economy, society and governance through technology. This S&T diplomacy has the potential to not only strengthen Japan’s external action, but also to transform its industries and research while it is transforming the infrastructures of Japan’s partner nations, like the construction of subway and high-speed rail networks in India. This article will first analyze the theoretical framework of public diplomacy and science and technology diplomacy. Next, Japan’s public diplomacy will be studied by comparing The Soft Power 30 and Global Soft Power Index. Finally, Japanese science and technology diplomacy will be analyzed by assessing the initiatives contained in the Japanese Society 5.0 project.

Rationale for the Use Of Radonometry to Identify the Areas of Tectonic Faults During the Passage of Subway Tunnels in Dnipro

Purpose. The article is aimed to substantiate the choice of the most effective method of geophysical research within the metropolis for more accurate mapping of fault zones in erupted rocks for the purposes of 2nd stage subway construction in the city of Dnipro. Methodology. Practical and organizational measures for radonometry for seismotectonics during the 2nd stage construction of the city subway were developed in detail, which in case of continued mining operations in the ravine-beam system contributes to further safe operation of the facility. Findings. Based on the analysis and evaluation of all profile studies conducted in the city in different years, one of the emanation methods was chosen – radonometry, and the method for its implementation was proposed, which provides dense urban development and complex tectonic structure of the region (fault zones) to obtain the necessary quality characteristics of soil incision. Originality. This paper for the first time provides a rationale for radonometry to identify fault zones in erupted rocks and assess their activity within the city. Practical value. The given technique is recommended for ensuring seismically safe conditions of drilling and blasting works during the passage of mine workings, which will ensure the maximum construction speed. In the future, these studies may be required when creating a ventilation system for underground structures of the 2nd stage of the city subway. Also, the radonometry results can be taken into account when placing elements of geotechnical (deformation) monitoring systems, both in tunnels and other deep-seated subway structures, and in buildings and structures. Clarification of the position of fault zones with the assessment of their activity can directly affect the choice of certain methods of measuring the deformation parameters of the observed objects, facilitate the choice of means of tunnel processing, highlight their qualitative or quantitative parameters.

Underground space in metro area: constituent, influencing factors and improving strategies of the spatial vitality

Nowadays, the shortage of available urban land and the booming construction of urban subway are driving the rapid development of Underground Space in the Metro Area (USIMA) which is an important constituent in the compact development of cities. Spatial vitality, as one of the most important evaluation indicators for the layout of such metro-related underground space, is closely related to spatial efficiency. Therefore, taking Shanghai People’s Square Metro Station (SPSMS) as a case study, this paper investigated the variable factors of the spatial vitality in USIMA by using methods of space syntax, field investigation, and pedestrian counting. Results revealed that the spatial vitality of USIMA is comprehensively affected by related variables, including accessibility and visibility of spatial configuration, degree of functional mixture, layout of station hall as well as entrances/exits, and the organization of business forms. Finally, improvement suggestions and discussions are put forward from the aspects of entrance/exit layout, spatial organization, and functional distribution, to provide reference for future planning, design and optimization of USIMA with effective vitality.

Research and Engineering Application of Soft Soil Unloading and Deformation Model

Soft soil is a multiphase medium composed of solid soil particles, pore water, pore gas and combined water film adsorbed on the surface of particle group and colloid between particles. It is widely distributed in coastal, middle and lower reaches of rivers and delta of lakes. Its physical and mechanical properties and engineering characteristics are complex and regional differences are obvious. With the rapid development of social economy and urbanization, it will inevitably lead to serious problems such as urban land tension, traffic congestion and environmental pollution. These coastal cities are the leaders of China’s economic development. After more than 30 years of rapid economic development, the construction scale of these cities in China is also expanding, and the supply and demand of construction land is becoming increasingly tight. The contradiction between supply and demand is more prominent. With the scarcity of land resources and the rapid development of economy, a large number of construction projects in Qianhai area have been started, among which the construction of subway is also on a large scale. The shortage of land resources and the increase of land development make the high density and high strength building development along the subway line. The development of these building properties is bound to appear a large number of complex deep foundation pit projects, and the excavation of deep and complex foundation pit near the side of subway tunnel is a common form of excavation. In practical construction projects, due to the influence of external factors such as complex construction site conditions and urgent time requirements, people often pursue the progress of foundation pit excavation too much in actual construction, ignoring the research and application of mechanical properties of soft soil foundation, which leads to the safety accidents of subway tunnel structure from time to time. This is closely related to the mechanical properties of soft soil with high moisture content, high compressibility and low bearing capacity. Therefore, deep and large foundation pit engineering in soft soil area is prone to heavy engineering safety problems such as underground continuous wall and other retaining structures. Therefore, the further study of the unloading deformation model of soft soil, the physical and mechanical properties and engineering characteristics of soft soil has a positive and important economic value and social role in engineering in the future.

Ground Settlement analysis of Metro Interval using PBA method in the Loess region

In the construction of urban subway, the control of surface settlement has become the key and difficult point in the construction. As a common method in subway tunnel construction, PBA method has been widely used in many areas in China. This method performs well in settlement control. In addition, the supporting system of piles, beams, and arches formed during the construction process of this method effectively avoids the impact of the open-cut method on urban traffic. Therefore, this paper will combine the engineering conditions and the existing research results to simulate the various construction stages of the subway interval excavation in the loess area by establishing a Midas model. Combined with the results of numerical simulation, four increasing stages of surface settlement and corresponding settlement ratios are obtained, and the characteristics of surface settlement troughs are analyzed. This research is helpful to further understand the increasing law of ground settlement during the construction of metro interval in loess area.

Analysis of Ground Deformation Caused by Subway Tunnel Excavation in Kunming

Research at home and abroad shows that subway excavation often causes soil stress loss, resulting in settlement deformation and horizontal displacement of stratum. Therefore, combined with the special engineering geological conditions in Kunming area, the foundation deformation caused by subway excavation is studied, so as to provide an important foundation for proposing the protection measures of surrounding buildings and buried pipelines and promoting the construction of subway.

Monitoring Subsidence Deformation of Suzhou Subway Using InSAR Timeseries Analysis

Subway subsidence and the consequent geological hazards have become one of the major concerns especially in China's large cities. Large spatial-scale and temporally continuous measurements of surface deformation due to subway subsidence is the basis of the intelligent management for urban transit, as well as the guarantee for the early warning of geological disasters. In this paper, we used persistent scatterer interferometric synthetic aperture radar (PS InSAR) measurements to study and characterize the deformation process resulted from subway-induced subsidence in the construction and operation periods of Suzhou subway using 24-scene high-resolution TerraSAR data (from December 2009 to April 2015) and 19-scene low-resolution Sentinel-1A SAR data (from May 2017 to February 2020). Our results indicate spatially different subsidence rates at different segments along the Suzhou subway lines 1, 2, 3, 4, 5 and 6. TerraSAR data indicate the maximum subsidence rate of -13 mm/yr, while Sentinel-1A data demonstrate the maximum subsidence rate of -20 mm/yr. The decadal-scale subway subsidence deformation is generally characterized by its multistage dynamic processes. The significant subway subsidence is mainly distributed around interchange hubs at the intersection area of railway lines. The Peck function model is used to fit the subway subsidence displacement profiles, which reveals the normal distribution characteristics of the subway surface subsidence. Based on our timeseries analysis in different time periods, the logistic cycle function is used to invert the subway subsidence timing, which reveals four first-order stages during subway subsidence: slow acceleration period, fast acceleration period, decay period and steady-state period.

Research on energy-saving characteristics of battery-powered electric-hydrostatic hydraulic hybrid rail vehicles

With the advantages of no emission and low noise, battery rail vehicles (BRVs) are widely used in the construction of subway, high-speed railway and so on. However, the problems of low energy efficiency and peak power shock of traction motor have severely restricted the application and promotion of BRVs. To address these problems, an electric-hydrostatic hydraulic hybrid powertrain (EH3) is designed in this paper. Friction braking (FB) is replaced by hydraulic regenerative braking (HRB) and the mode of recovered hydraulic energy coupled at the inlet of pump (ECIP) to assist acceleration is proposed. The energy conservation characteristics of recovery and coupling of hydraulic energy in EH3 powertrain are verified by simulation and laboratory test bench. The energy recovery efficiency of HRB is up to 50% and the new coupling modes can greatly reduce the consumption of electric power. The control strategy is designed to coordinate different working modes which are established based on the high-pressure accumulator (HPA) and the driving state parameters of BRVs. The simulation result shows that the energy consumption of the battery can be reduced by 17.32%. The EH3 powertrain has broad application prospects in realizing energy conservation, reducing peak motor power shock and improving the braking performance of BRVs.

Control of Environmental Safety in the Construction of Subway in Megapolis

It was noted that in the construction of subways, the achievement of planned indicators is possible with the use of innovative construction technologies, in particular of tunnel boring machine (TBM). The analysis of the factors that determine the negative impact on the environment when using the TBM is compared with civil construction. The scientific novelty and practical results is given. It was proposed to take into account the degree of attractiveness of the territory when deciding on the location of construction sites. An approach is proposed to determine the attractiveness of the territories for the construction of metro facilities. The task of managing environmental safety during the construction period has been formulated. The procedure for managing environmental safety in the construction of subway lines is given. It is shown that as criteria for making management decisions, indicators characterizing the degree of influence of the physicochemical nature on the state of the environment should be used. It is said that the most rational option for minimizing the negative impact on the OS should be considered as a complex implementation of measures, at which simultaneous reduction of several negative factors to achievable levels is achieved: noise and vibration effects, pollutants of various chemical nature entering the atmosphere, etc. The principles of environmental safety management during noise and vibration effects, as well as the disposal of soil and soils formed during the construction of metro facilities are substantiated

Development of an automatic monitoring system for ground settlement induced by shield tunnelling

During the construction of the modern subway, it is often the case that subway tunnel construction is close to existing buildings, causing the deformation of existing buildings. In order to minimize the impact of new line construction, real-time monitoring and feedback warning of building deformations are required. This paper is based on the current mature automated monitoring data acquisition system. A comprehensive monitoring management system is developed, which includes engineering information management, monitoring equipment management, monitoring data reception, monitoring data analysis and processing, early warning information release as well as monitoring report automatic output. The developed automatic monitoring system was applied to the monitoring of the construction of Chengdu Metro Line 5, completed the automatic monitoring and real-time data processing and early warning of the underpass process. The operation safety of the existing lines was guaranteed. In the future, this system will also be extended to other tunnel monitoring, gradually forming a comprehensive tunnel construction monitoring and management system.

Deformation of deep and large foundation pit in soft soil of Fuzhou Subway

In order to study the deformation law of deep and large foundation pits in the soft soil layer of Fuzhou, 22 lines of 2#, 5#, and 6# lines of the rail transit system in Fuzhou area are covered by 1 m underground continuous wall or 850SMW method piles + multi-layer. The measured data of the inner-supported long-shaped subway foundation pits were statistically analyzed and compared with the research results of similar projects at home and abroad. The results show that (1) the maximum horizontal displacement δhm of the continuous wall of the subway pit is 0.078–0.15% Hm, the average value is 0.118% Hm; (2) the maximum horizontal displacement point of the retaining structure is located at a distance of about 8 m; (3)the maximum settlement value δvm is in the range of 0.057–0.124% Hm, and the influence range is about 4.5 Hm; (4) the range of δvm/δhm of the foundation pit of the subway station is 0.13–1.07, and the average value is 0.96; (5) the range of the column bulge value δcu of the station foundation pit is 0.05–0.11% Hm. The research results of this paper can provide reference for the design and construction of other subway (3#, 4#, 7#, 8#, and 9#) stations and similar foundation pit supporting structures in Fuzhou.

Geological Disaster Survey and Treatment Strategies of Yingwanzhen Subway Station, Changsha

In order to solve such problems as ground subsidence, water and mud bursting and shield machine foundering in subway construction which are caused by water-rich karst geological conditions, complete technological process is established to detect and treat karst in urban areas. The occurrence of natural electric field frequency selection method and groundwater determine groundwater occurrence vector that karst and fault fracture zone, and make use of the grouting technology of karst fracture with the treatment. The construction of Yingwanzhen Stationon Changsha Metro Line No. 4 provesthe favorable effect of the detection technology and treatment measures, which provides experience and reference for the construction of Changsha subway and underground engineeringin other cities with water-rich karst areas.

Analysis of Deformation of Ground and Connected Aisle with the Influence of Sump-Pit Excavation in the Aisle

The excavation of connected aisle is one of the key risks for the construction of subway in the coastal soft clay layer. The excavation of sump-pit will adversely affect the deformation of the ground and connected aisle, increase the risk of the project. The finite element software ABAQUS is used to carry out numerical simulation research on the excavation of sump-pit. The influence of deformation of ground and connected aisle were analyzed by the method of changing the position of sump-pit excavation. The result showed that: the most significant influence of sump-pit excavation was crown settlement, the second important influence was ground settlement, and the influence of headroom convergence was slight. The maximum ground settlement increased by 7% and the maximum crown settlement by 13% if the sump-pit was built in the middle of connected aisle.

Research and Application of Shaft Excavation by Deep Hole One-Time Blasting Technology

In the construction of subway, tunnel, mining and other underground projects, in order to speed up the construction progress, it is often necessary to excavate a shaft first and then dig at both ends of tunnel at the same time. The shaft excavation is a difficult problem in underground engineering. At present, the shaft excavation construction mainly adopts upward construction method and downward construction method, which are characterized by high labor intensity, high risk coefficient and slow construction speed. In order to realize the efficient excavation of vertical shafts, this paper presents a technology of deep hole one-time blasting into wells. Based on theoretical analysis and practical shaft engineering, the blasting parameters of the deep hole one-time blasting technology are given, such as hole diameter, spacing, layout, charge structure and blasting sequence of each hole, and the technical scheme is formed finally. The technology is applied in a shaft excavation construction in Changping District, Beijing of China and good results are obtained, which proves that the technique is feasible.

Analysis on Influencing Factors of Blasting Vibration Caused by Shallow Tunnel Excavation

With the widespread construction of urban subway, more and more shallow tunnels will be constructed by blasting, and the problem of blasting vibration will become more prominent. Because of the randomness and variability of blasting source and topographic and geological factors, the propagation mechanism and influencing factors of blasting vibration wave are very complex. Based on blasting-vibration sample data obtained from the established numerical model of blasting excavation in shallow tunnel, the relational degree analysis was carried out for influencing factors of blasting vibration caused by shallow tunnel excavation with method of grey relational analysis. The results of the study are as follows: Among the four related factors, there is no optimal factor, and the maximum charge of one section is the quasi-optimal factor; The charge of the first section is the main factor affecting the peak particle velocity of blasting vibration; The maximum charge of one section is the main factor affecting the main frequency of blasting vibration; The delay interval is the main factor affecting the duration of blasting vibration. Furthermore, the measures to control blasting vibration caused by shallow tunnel excavation were put forward, such as reducing the charge of the first section, reducing the maximum charge of one section and rationally setting up the delay interval. The study has important guiding significance for safe blasting construction in shallow tunnel and scientific control of blasting vibration effect.

Research on the effects of the excavation of cross passage for the displacement of tunnel and the surface of earth

In the construction of urban subway, the excavation of the cross passage is usually carried out after the completion of the main tunnel. At the same time, it is necessary to ensure the safety of the cross passage itself and the stability of the main tunnel and the normal access of the ground is also indispensable. Therefore, it is of great significance for the whole project to accurately grasp the scope of influence and the rule of change of the construction of cross passage. Based on the cross passage of subway in Xuzhou, the influence of the excavation of cross passage on vertical, horizontal displacement of tunnel and the settlement of ground is studied through the finite element software called MIDAS GTS/NX. The following conclusions are drawn:the curve of the settlement of the upper part of the tube, the uplift of the lower segment and the convergence of tunnel caused by the excavation of the cross passage are “U”, half pentagonal, and triangular and the influence of tunnel with hole side is obviously greater than that of the other side tunnel. Besides, the overall range of impact is within 30m of the longitudinal distance from the central line of the tunnel. The tunnel eventually moves upwards and it moves toward the direction of the cross passage. The settlement curve of the change of surface caused by excavation of cross passage is basically the shape of “U”. The main influence area is 15m within the center line of cross passage and the settlement of the soil near the middle line of the connecting passage is the most obvious, 6.5mm. In addition, all values meet the requirements of the deformation of control, which confirms the effect of the reinforcement of grouting.

Overview of Anti-Seismic Researches of Underground Structures

With the vigorous development of urban rail transit system, especially the construction of subway system, the safety of subway system draws more and more attention. The study of anti-seismic for underground structures has also become an important problem to be solved in the construction of Metro system. Based on the typical underground structure seismic damage phenomenon, this paper summarizes the seismic characteristics, research methods and design methods of underground structures to offer a guide for engineers.

Environment Impact Analysis of Shield Passing Alongside Bridge Pile Platform Using Three Dimensional Numerical Simulation

The shield method has many advantages in the construction of urban subway, and has become the preferred method for the construction of urban subway tunnel. Taking Shijiazhuang metro line 3 (administrative center station - garden park station interval) Passing alongside bridge as the engineering background, double shield crossing the bridge pile foundation model was set up. The deformation and internal force of the pile foundation during the construction of the shield were analyzed. Pile stress caused by shield construction increases, but the maximum stress is less than the design strength; the maximum surface settlement caused by the construction of 10.2 mm, the results meet the requirements of construction.