High-speed Railway Construction Research Articles

Stress–Strain–Time Description and Analysis of Frozen–Thawed Silty Clay under Low Stress Level

The construction of high-speed railways in cold regions needs to consider the effects of freeze–thaw cycles (FTHs) on the long-term deformation of subgrades. However, at present, research on the creep characteristics of frozen–thawed rocks and soils is not extensive. In the limited studies on frozen–thawed soil creep properties, current research focuses more on high stress–strain–time responses, but for the subgrades, the inner stress is usually low. This paper presents the results of triaxial compression creep tests on remolded, frozen–thawed silty clay sampled in the Yichun-Tieli area and describes its stress–strain–time relationship in an arctan function-based mathematical model. Each creep test condition is studied using three specimens. Frozen–thawed silty clay exhibits attenuation creep under low-level stress. In general, from 4 FTHs to 11 FTHs, the mean elasticity modulus decreases first, and then, increases. The exerted stress is higher than the yield stress; the more FTHs the specimens experience, the more time they need to be deformed stably under the same axial deviatoric stress (ADS). Under the same mean ADS, the mean stable strain of 7 FTHs exceeds the other two FTH conditions and, in general, the mean stable strain of 4 FTHs exceeds 11 FTHs. By dissecting the phenomena, it can be concluded that with FTHs increasing, moisture and voids reconstitute in the process; the elastic strain accounts for most of the total strain and significantly decides the extent of creep deformation; the arctan function-based model is basically able to describe, but not perfectly predict, the stress–strain–time relationship of frozen–thawed silty clay.

Does High-Speed Railway Promote the Level of Human Capital? An Empirical Analysis Based on Three Urban Agglomerations in China

This paper analyzed the impact of high-speed railway (HSR) construction on human capital and its mechanism by establishing high-speed railway-city level panel data from 2003 to 2019 and constructing a multiperiod difference- in-differences (DID) DID model in China. The results showed that HSR has significantly promoted the level of human capital in Beijing–Tianjin–Hebei urban agglomeration, Yangtze River Delta urban agglomeration, and Pearl River Delta urban agglomeration in China, with the overall effect value of 20.8%. The conclusion that HSR promotes the level of human capital is still valid through endogenous treatment of the instrumental variable method and robustness test. Further analysis showed that the impact of HSR construction on the level of human capital in urban agglomerations is mainly through the labor mobility and education investment potential, with the effect values of 3.65% and 4.44%, respectively. The findings of this paper highlight the importance of exploiting the external utility of HSR, improving the level of regional human capital, and promoting high-quality economic development of urban agglomerations.

О прогнозировании пассажиропотоков для высокоскоростных магистралей с учетом конкуренции на рынке пассажирских перевозок

Purpose: The study of the problem of passenger traffic forecasting for high-speed railways given peculiarities of regional development and competition in passenger transportation market in Russian Federation conditions. The influence of a large number of different factors on passenger traffic volume formation is the main reason for the difficulty of obtaining reliable forecasts of passenger traffic in the long term. Based on the analysis of Russian and foreign scientific papers, devoted to the problem under study, the most significant factors were identified from ones’ variety: population, per capita income, gross domestic and regional products. The analysis showed that scientists ambiguously assess the impact of gross regional product on passenger traffic volume. The authors investigated the relationship between the volumes of passenger traffic and gross regional product on directions of being projected high–speed railways Moscow - St. Petersburg and Moscow — Kazan. As a result, the sections of gross regional product with the greatest degree of influence on passenger traffic were identified. Also, in modern conditions, concurrence in passenger transportation market has significantly increased which mainly determines the distribution of passenger traffic by transport kinds. Methods: System analysis, correlation and regression analysis, time series analysis. Results: The obtained results showed that in market conditions, because of the dynamism and uncertainty of population’s demand for transport services which is caused by a passenger’s choice of traffic method depending on transportation travel time, cost and comfort; the complexity of forecasting passenger traffic has increased. Two variants of passenger traffic forecasting methodology for high-speed highways are proposed in view of competition in the passenger transportation market. Practical significance: The application of a mathematical model for forecasting passenger traffic, taking into account the peculiarities of Russian Federation regions development and the competition between different kinds of passenger transport, will allow to obtain a reliable estimate for promising passenger traffic volumes that will provide for the reduction of investment risks in the construction and operation of capital-intensive high-speed railways.

The Impact of High-Speed Railway Opening on Regional Economic Growth: The Case of the Wuhan–Guangzhou High-Speed Railway Line

With the advent of the “ear of high-speed railways”, the space–time distance between cities has drastically decreased. The opening of high-speed railways has not only increased the factor-flow speed across regions, but has also reduced the cost of factor movement. However, there is some controversy about whether high-speed railways can be used to promote regional economic growth. The Wuhan–Guangzhou high-speed railway is the earliest section of the Beijing–Guangzhou high-speed railway, and it was the first high-speed railway in China with a real speed of 350 km per hour. The Wuhan–Guangzhou high-speed railway opening spawned a three-hour economic circle in the south of China, injected new vitality into the economic and social development along the line, and had an important impact on accelerating regional economic interoperability and integration. Taking this into account, this paper took the Wuhan–Guangzhou high-speed railway as the case study. Firstly, this paper used the theory of system dynamics to analyze the mechanism of the impact of high-speed railway opening on regional economic growth. Secondly, the accessibility model was used to analyze the impact of the high-speed railway opening on the accessibility of cities along the line, and a difference-in-differences model (DID) was used to explore the impact of the high-speed railway opening on regional economic growth. Finally, on the basis of the analysis of the previous mechanism, the mechanism of the impact of the high-speed railway on regional economic growth is discussed. The results of this study show the following: (1) Since the opening of the high-speed railway, the accessibility of cities along the line has grown by more than 60%. (2) The opening of the high-speed railway has promoted regional economic growth, mainly through the influence mechanism of “increasing the total cargo volume”. This study not only scientifically and quantitatively analyzed the impact of the opening of high-speed rail on regional economic growth, taking the Wuhan–Guangzhou high-speed railway as an example for empirical analysis, but also further summarized the high-speed railway construction achievements in China and provides reference experience for planning the opening of high-speed railways.

Research on the synergies between low-carbon pilot city policy and high-speed railways in improving Chinese urban electricity efficiency

PurposeGlobal climate change is a serious threat to the survival and development of mankind. Reducing carbon emissions and achieving carbon neutrality are the keys to reducing greenhouse gas emissions and promoting sustainable human development. For many countries, taking China as an example, the electric power sector is the main contributor to the country’s carbon emissions, as well as a key sector for reducing carbon emissions and achieving carbon neutrality. The low-carbon transition of the power sector is of great significance to the long-term low-carbon development of the economy. Therefore, on the one hand, it is necessary to improve the energy supply structure on the supply side and increase the proportion of new energy in the total power supply. On the other hand, it is necessary to improve energy utilization efficiency on the demand side and control the total primary energy consumption by improving energy efficiency, which is the most direct and effective way to reduce emissions. Improving the utilization efficiency of electric energy and realizing the low-carbon transition of the electric power industry requires synergies between the government and the market. The purpose of this study is to investigate the individual and synergistic effects of China’s low-carbon policy and the opening of urban high-speed railways (HSRs) on the urban electricity consumption efficiency, measured as electricity consumption per unit of gross domestic product (GDP).Design/methodology/approachThis study uses a panel of 289 Chinese prefecture-level cities from the years 1999–2019 as the sample and uses the time-varying difference-in-difference method to test the relationship between HSR, low-carbon pilot cities and urban electricity consumption efficiency. In addition, the instrumental variable method is adopted to make a robustness check.FindingsEmpirical results show that the low-carbon pilot policy and the HSR operation in cities would reduce the energy consumption per unit of GDP, and synergies occur in both HSR operated and low-carbon pilot cities.Research limitations/implicationsThis study has limitations that would provide possible starting points for future studies. The first limitation is the choice of the proxy variable of government and market factors. The second limitation is that the existing data is only about whether the high-speed rail is opened or not and whether it is a low-carbon pilot city, and there is no more informative data to combine the two aspects.Practical implicationsThe findings of this study can inform policymakers and regulators about the effects of low-carbon pilot city policies. In addition, the government should consider market-level factors in addition to policy factors. Only by combining various influencing factors can the efficient use of energy be more effectively achieved so as to achieve the goal of carbon neutrality.Social implicationsFrom the social perspective, the findings indicate that improving energy utilization is dependent on the joint efforts of the government and market.Originality/valueThe study provides quantitative evidence to assess the synergic effect between government and the market in the low-carbon transition of the electric power industry. Particularly, to the best of the authors’ knowledge, it is the first to comprehend the role of the city low-carbon pilot policy and the construction of HSR in improving electricity efficiency.

Field Research on the Treatment of Coastal Phase Liquefaction Foundation with Clay Interlayer Using Resonance Probe Compaction Method

The resonance probe compaction (RPC) method is an effective technique for particular soils, which mainly includes sandy and loess. However, the application of RPC on contaioning clay interlayer area has never been seen. In this study, a successful case of using the RPB method to treat the clay interlayer foundation is presented in detail. The test results of Huaiyan high-speed railway construction project are introduced. The test is divided into the laboratory test and the field test, mainly including standard penetration test (SPT), cone penetration test (CPT) and seismic wave cone penetration test (SCPT). The test results indicated that the cone resistance of silt and silty sand layers increased to an average of 2.13 times compared with an average of 4.39 MPa before treatment, and the sleeve friction whose initial average is 54.17 kPa increased to an average of 1.74 times. The existence of the clay interlayer does not affect the consolidation and drainage of the silt layer and the silt sand layer, and after the construction, the excess pore water pressure around the vibration point can be dissipated by more than 90% within 15 minutes. After reinforcement, the standard penetration number of subsoil, increased by about 15%–95% compared with an average of 19 blows before treatment and the clay particle content of some clay interlayers are reduced to less than 10%. The shear wave velocity of the subsoil in the treatment depth increased by about 15%–48% compared with 140 m/s before treatment. The RPC method was successful for the coastal phase liquefaction foundations.

A novel evaluation method of mining goaf ground activation under high-speed railway load

With the continuous improvement of infrastructure, some high-speed railway lines will inevitably cross the goaf ground, and there is less research on the safety of high-speed rail construction in goaf ground. To make a reasonable and accurate safety evaluation of the high-speed railway construction in the mine goaf ground, machine learning combined with numerical simulation is used to evaluate the safety depth of goaf under the impact of high-speed railway load. An optimal algorithm is selected among BP, RBF, and PSO-RBF neural networks based on the accuracy of the predicted height of a caving fracture zone. Numerical models for simulating high-speed railway founded on goaf are set up using the commercial software package FLAC3D, where factors such as subgrade height, train speed, and axle load are investigated in terms of train load disturbance depth and the extent of the caving fracture zone. The results indicate that the PSO-RBF neural network has an error of 2.76% in predicting the height of the caving fracture zone; the depth of train load disturbance is linearly related to the axle weight and roadbed height but is a sinusoidal function of the train speed. Based on the numerical simulation results, a formula for calculating the depth of train load disturbance is proposed, which provides a certain reference value for the construction of high-speed railways in the goaf ground.

Seismic performance of near-fault geosynthetic-reinforced pile-supported embankment

The seismic performance of embankments is an important consideration for the design and construction of high-speed railways (HSRs) in near-fault areas. Incorporating geosynthetics into embankment soil can improve seismic resistance. However, the effect of different reinforcement methods on the seismic performance of embankments is not well understood. In this study, two 1 : 20 scaled embankment models (full-length-geosynthetic-reinforced pile-supported embankment (FRPE) and turn-back-geosynthetic-reinforced pile-supported embankment (TRPE)) were tested on a shaking table to compare their seismic performance and failure characteristics. The results show that under near-fault bidirectional seismic excitation, the pile foundations of both embankments exhibited bending deformation, with the largest bending moment in the middle of the pile body. The TRPE reduced the vertical dynamic response of the embankment slope but exhibited a more remarkable horizontal dynamic response than the FRPE. Furthermore, the embankment deformation and excess pore water pressure of the TRPE were generally larger than those of the FRPE. Nonetheless, the TRPE has potential application in practical engineering as it ensures earthquake resistance, with higher economic benefits.

Evolutionary power spectrum density of earthquake-induced rail geometric irregularities

China’s high-speed railway (HSR) construction has gradually extended to earthquake-vulnerable areas in recent years. However, there is currently a lack of studies on the characteristics of earthquake-induced rail irregularities, making it impossible to ascertain the threshold of post-earthquake train running speed. Taking the multi-span HSR simply supported girder bridge of a CRTS II-type track system as the research focus, the distribution models for residual rail irregularity under random seismic actions have been analyzed in this study. The statistical distribution of the evolutionary power spectrum density (EPSD) of the residual rail irregularity set is also explored. Based on the obtained results, the EPSD of earthquake-induced rail geometric irregularity was calculated, and a time-domain sample for earthquake-induced rail geometric irregularity was developed. Finally, the equating method of earthquake-induced rail geometric irregularity under different span numbers was discussed, and a method for fitting earthquake-induced rail geometric irregularity was proposed.

A New Classification Method of Mine Goaf Ground Activation Considering High-Speed Railway Influence

With the rapid development of high-speed railways in China, it is inevitable that some of the lines will have to traverse through the mine goaf ground, and there is little research on whether the “activation” of the foundation of the mine goaf ground occurs under the influence of train loads. In order to provide a safe and reliable basis for the construction of high-speed railway in mine goaf ground, a new classification method of mine goaf ground activation is proposed considering the stability and railway influence. First, the stability evaluation system of the mine goaf site is established with 3 primary indexes and 12 secondary indexes. The 47 groups’ data of the mine goaf ground site are collected as learning samples. Five machine learning methods including decision tree, discriminant analysis, support vector machine, and classifier ensemble are used to learn and test the data. The optimal algorithm is selected and the stability evaluation model is established to classify the stability of the mine goaf site. Second, influencing factors of railway are graded to establish an extension comprehensive evaluation model. Finally, based on the above two models, a new classification method of high-speed railway goaf ground activation considering the two factors and five sub-factors is proposed. Through the verification of two engineering examples, the prediction result of this method is “easily activation” and the need to treat the goaf area, and the actual construction is also taken to grouting treatment, proving that the method has certain guiding significance for the project.

Resilience Evaluation of High-Speed Railway Subgrade Construction Systems in Goaf Sites

When the high-speed railway construction project passes through goaf sites, the uncertain impacts from internal and external environments faced by the system are gradually characterized by complexity and variability, and the disastrous consequences are becoming increasingly prominent. The risk resistance ability and accident recovery ability of the high-speed railway subgrade construction system are crucial for improving the safety management level of the construction site. Based on the concept of resilience, this paper discusses the connotation of resilience applicable to the construction system of high-speed railway foundations in goaf sites, and an evaluation index system including 25 indicators is constructed. Then, the resilience evaluation model is constructed by ANP, entropy weight method and fuzzy comprehensive evaluation method. Taking the construction system of Taijiao high-speed railway subgrade in the underlying goaf as an example, this model is verified. The verification results show that the grade of construction system is II (high resilience). The evaluation result is consistent with the actual engineering situation, and the evaluation model is effective. It can be used as a theoretical basis for safety management of high-speed railway construction projects, and a full process analysis method based on resilience theory is established.

Impact of Rapid Transit Development on Urban Economic Growth: An Empirical Study of the Urban Agglomerations in China

Transportation infrastructure and market integration play an important role in building China’s new development pattern of dual circulation. Taking 220 cities in 19 urban agglomerations in China as the study sample, this study analyzes the impact of rapid transit development on urban economic growth from 2008 to 2019 and examines the heterogeneity of the difference in market integration capability in promoting urban economic growth based on the two-way fixed effects model. The main conclusions are as follows: 1) the improvement of travel convenience brought about by the development of expressways and high-speed railways significantly promoted urban economic growth; 2) market integration has significantly restricted the promotion of the construction of expressways and high-speed railways to urban economic growth. In other words, cities with less market integration have greater economic benefits from expressway and high-speed railway construction; 3) there is a certain substitution of the role of expressways and high-speed railways in promoting urban economic growth, and for cities that already have a relatively complete expressway network, further construction of high-speed railways will inhibit the promotion effect of expressway development on urban economic growth; 4) expressway and market integration have a stronger role in promoting urban economic growth in the eastern region than in the central and western regions, while high-speed railway and market integration promote the economic growth in the eastern region, and the impact on economic growth in the central and western regions is not significant. The findings of this study have implications for optimizing the planning of expressway and high-speed railway construction and promoting high-quality regional development in China and other developing countries.

Analyzing and Controlling Construction Engineering Project Gray Rhino Risks with Innovative MCDM Methods: Interference Fuzzy Analytical Network Process and Decision-Making Trial and Evaluation Laboratory

Construction engineering projects are costly and require large amounts of labor, physical, and financial resources. The failure of a construction engineering project typically brings huge losses. Previous studies have focused on the identification of risks, but insufficient attention has been given to strategic resource allocation for risk management after risk identification. Statistics show that most construction engineering project failures are caused by common risks. Common risks are called gray rhino risks. This metaphor illustrates that many risks are obvious but dangerous. This study was motivated by the challenge of efficiently managing gray rhino risks with limited inputs. The literature suggests that gray rhino risks are abundant in construction engineering projects and that there are mutual eliciting relationships between them, which make it difficult for the manager to devote enough resources to the prevention of key risks. Considerable resources are wasted on unimportant risks, resulting in key risk occurrence and failure of construction engineering projects. Therefore, this study describes an innovative multi-criteria decision making (MCDM) technique for ranking risks based on the strength of the eliciting relationships between them. This study used the fuzzy technique and created an interference fuzzy analytical network process (IF-ANP) method. By employing the IF-ANP alongside a decision-making trial and evaluation laboratory (DEMATEL) approach, the subjectivity can be effectively reduced and the accuracy improved during expert risk evaluation for construction engineering projects. IF-ANP was used to quantify eliciting relationships between risks and DEMATEL was used to rank risks based on the IF-ANP result. An empirical study was done to meticulously rank five risks that were selected from the gray rhino risks in the Chengdu–Chongqing Middle Line High-speed Railway construction engineering project. They are capital chain rupture, decision failure, policy and legal risk, economic downturn, and stakeholder conflict. The results showed that the policy and legal risk was the source of other risks, and that these other risks were symptoms rather than the disease.

Analysis of Load Transfer Law of Short Pile-Net Composite Foundation for High-Speed Railway

Although pile-net composite foundation has been widely used in the construction of high-speed railway, load transfer characteristics of its structural system during the filling of roadbed are seldom studied, so field studies are conducted in the Gan-Long (Ganzhou-Longyan) high-speed railway DK86 + 998.0–DK87 + 191.2 test section, aiming to explore the bearing characteristics of a short pile-net composite foundation over low to medium compressible soil. The study encompasses a field measurement of Earth pressure and pore water pressure which lasted almost two years, and a systematic analysis of variation law of soil pressure between piles and their tops and that of pore pressure in reinforcement zone and retaining layer in medium and low compressibility soil area. The results suggest that the soil in the test section bears the characteristic of a low water content, low porosity ratio, and high liquid limit, with compression factor being approximately 0.25, and test values of the natural soil pressure and the lateral distribution are close to the theoretical values. Soil pressure at the top of the piles is higher than that between the piles by approximately 2.4 times because of the differences in pile-net rigidity. Besides, the soil pressure of the pile-net composite foundation follows the pattern of “jagged” in the transverse direction of the roadbed. The filling load of the composite foundation soil arch is 80 kPa and the composite foundation reaction coefficient is 6.4 kN/m3 when the filling is stable. The pile-soil stress ratio at the shoulder and the center of the line is 3.2 and 2.8, respectively. The change of the hole pressure at the pile end point is larger than that at the reinforcement area, and the side verification short pile can effectively transmit the additional stress of the upper part to the pile end soil layer.

Research on integrated control strategy of doubly‐fed induction generator‐based wind farms on traction power supply system

With the large-scale construction of high-speed railway and wind farms, the traction power supply system (TPSS) and wind farms are connected through the power system. The three-phase unbalance of grid voltage caused by the TPSS will seriously affect traditional wind farms’ operation control. Considering the TPSS and wind farms are connected to the power system's public point of common coupling (PCC), the wind farm's current control and voltage support strategy are studied. Firstly, aiming to suppress the influence of harmonics and the unbalanced power grid caused by the TPSS, the repetitive controller (RC) is introduced to the current control of the doubly-fed induction generator (DFIG). The vector control strategy based on the combination of proportion integral (PI) and RC is adopted, where the PI controller is used to adjust the average value of DFIG output power and the RC regulator controls DFIG output sinusoidal stator current. Secondly, the wind farm's voltage support strategy is designed to reduce the voltage fluctuation caused by the TPSS's loads. By coordinating three measures of putting in reactive power compensation devices, DFIG working in voltage control mode, and limiting DFIG output active power, the voltage of wind farm and traction station is effectively supported. Finally, a simulation model with the TPSS and wind farm is built to verify the proposed control strategy's effectiveness.

Research on Dynamic Response and Construction Safety Countermeasures of an Adjacent Existing Line Foundation under the Influence of a New Railway Line

The excavation of a new high-speed railway causes the side slope adjacent to the existing line foundation to become airborne, and the excessive dynamic deformation or cumulative deformation caused by the dynamic load of trains will affect the normal service of the subgrade, even leading to its instability. To date, there are no relevant experimental data regarding this, and there is also a lack of corresponding specifications. The only available numerical simulation research results need to be verified in practice. Therefore, this study relies on the Shanghai–Nanjing intercity high-speed railway construction project adjacent to the existing Beijing–Shanghai line to carry out a subgrade dynamic response test to ensure the safe operation of the existing line. The test obtained the vibration displacement, frequency, acceleration, and other parameters of the existing subgrade construction in three stages: subgrade excavation, pile formation, and subgrade filling. From the test results: During the test period, the vertical surface vibration displacement and vibration acceleration have a certain attenuation along the depth direction. In the stage of subgrade excavation, the vibration displacement and vibration acceleration generated are the largest. The vertical vibration displacement amplitude reaches 1.9 mm, and the horizontal vibration displacement amplitude reaches 0.15 mm. The vibration frequency of the roadbed under the action of the train load is concentrated in the range of 0–50 Hz, and the vibration energy at the peak value is relatively large, which reflects the load action frequency of the train, and the peak value is mainly concentrated in the range of 20–40 Hz. These results show that the maximum vibration response peak appears in the subgrade excavation stage, that is, the most dangerous stage of the existing subgrade. The vibration acceleration and vibration displacement of each dynamic response parameter are important in that they reflect the dynamic performance of the subgrade and establish the index control standard, which can be used as a control index for roadbed dynamic stability monitoring. The dynamic test of the subgrade state provides data support for the reasonable opening of the construction skylight and the protection of the excavation slope. Taking into account the impact of piling vibration, technical measures such as static pressure, jumping construction, and setting up stress relief holes are adopted. The test results and engineering measures ensure the safe operation of the existing subgrade, and have important theoretical significance for guiding the construction of the new subgrade adjacent to the existing line.

Safety Risk Assessment Using a BP Neural Network of High Cutting Slope Construction in High-Speed Railway

High-speed railway construction is extending to mountainous areas, and the harsh environment and complex climate pose various risks to the slope construction. This seriously threatens human lives and causes huge economic losses. The existing research results on the construction safety risks of high cutting slope construction in HSRs are limited, and a complete set of safety risk assessment processes and methods has not yet been formed. Therefore, in this study, we aimed to develop a safety risk assessment model, including factor identification and classification and assessment data processing, to help project managers evaluate safety risks in high cutting slope construction. In this study, comprehensive identification of high cutting slope construction safety risks was carried out from three dimensions, risk technical specification, literature analysis, and case statistical analysis, and a list of risk-influencing factors was formed. Based on the historical data, a high side slope risk evaluation model was established using a BP neural network algorithm. The model was applied to the risk evaluation of HF high cutting slopes. The results show that the risk evaluation level is II; the main risks are earthwork excavation method, scaffolding equipment, slope height, slope rate, groundwater, personnel safety awareness, and construction safety risk management system. Finally, a case study was used to verify the proposed model, and control measures for safety risks were proposed. Our findings will help conduct effective safety management, add to the knowledge of construction safety risk management in terms of implementation, and offer lessons and references for future construction safety management of HSR.

Is Resilient Transportation Infrastructure Low-Carbon? Evidence from High-Speed Railway Projects in China.

Establishing resilient transport infrastructure is an effective way for cities to deal with external disturbances and uncertainties during rapid urbanization. However, human society is presently facing a series of sustainable development obstacles, where the energy shortage and environmental pollution are catching significant concerns. Hence, it is imperative to investigate the carbon emission of the growing number of resilient transportation infrastructure (RTI) projects. Through extracting the carbon emission factor (CEF), this study built the carbon emission measurement model (CEMM) to evaluate the carbon emission of 26 resilient high-speed railway construction projects in China. The results indicated that the carbon emissions of the entire high-speed railway infrastructure projects in China show regional and social environmental differences. Meanwhile, there are potential correlations and positive relationships between the resilience of the high-speed railway infrastructure projects and their carbon emission. Suggestions and recommendations for governments and construction enterprises are put forward to further improve the resilient and low-carbon development of transportation infrastructure in China.

How does high-speed rail construction affect air pollutant emissions? Evidence from the Yangtze River Delta Urban Agglomeration in China

Taking the construction of high-speed rail as a “quasi-natural experiment”, the panel data of 26 cities in the Yangtze River Delta from 2004 to 2018 were selected as samples, and a difference-in-differences model was constructed to study the impact of high-speed rail construction on air pollutant emissions. Furthermore, the meditating effect model and difference-in-differences model were built to explore the paths of high-speed railway construction affecting air pollutant emissions. According to the study, the construction of high-speed rail reduces industrial sulfur dioxide emissions and increases the emission of industrial smoke and dust, which are more obvious in areas with good economic conditions. The role of high-speed rail in reducing emissions is realized through the structure effect, technological effect and substitution effect. However, the construction/renovation process of high-speed rail lines or stations does increase the industrial smoke and dust emissions. In this study, the bidirectional effects of high-speed rail construction on different air pollutant emissions were identified, including the high-speed rail construction process into the research. Multiple paths of action were proposed, bridging the gap of existing studies. The study reveals that controlling the air pollution emissions throughout the full life cycle of the high-speed rail, from the construction process to its operation, was essential.

In Situ Experimental Study of Natural Diatomaceous Earth Slopes under Alternating Dry and Wet Conditions

Very few studies have focused on diatomaceous earth slopes along high-speed railways, and the special properties of diatomaceous earth under alternating dry and wet conditions are unknown. This paper studies diatomaceous earth in the Shengzhou area, through which the newly built Hangzhou–Taizhou high-speed railway passes, and the basic physical and hydraulic properties of diatomaceous earth are analyzed by indoor test methods. A convenient, efficient, and controllable high-speed railway slope artificial rainfall simulation system is designed, and in situ comprehensive monitoring and fissure observation are performed on site to analyze the changes in various diatomaceous soil slope parameters under rainfall infiltration, and to explore the cracking mechanisms of diatomaceous earth under alternating dry and wet conditions. The results indicate extremely poor hydrophysical properties of diatomaceous earth in the Shengzhou area; the disintegration resistance index values of natural diatomaceous earth samples subjected to dry and wet cycles are 1.8–5.6%, and the disintegration is strong. Comprehensive indoor tests and water content monitoring show that natural diatomaceous earth has no obvious influence when it contacts water, but it disintegrates and cracks under alternating dry and wet conditions. The horizontal displacement of both slope types mainly occurs within 0.75–2.75 m of the surface layer, indicating shallow surface sliding; after testing, natural slope crack widths of diatomaceous earth reach 10–25 mm, and their depths reach 40–60 cm. To guarantee safety during high-speed railway engineering construction, implementing proper protection for diatomaceous earth slopes is recommended.