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Study on the Dynamic Properties of Coarse-grain Soil under Different Reinforced Materials

LI Lihua, NING Tuo, MAO Wang, MEI Lifang, JIANG Shuguang, LIN Yuliang

Journal of Railway Engineering Society. 2025, 42(5): 1-6.

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Research purposes: In the subgrade of heavy-haul railways with significant axle loads, the strength of the subgrade is particularly crucial. Enhancing the strength of heavy-haul railway subgrades is an urgent issue that needs to be addressed in the field of engineering. To explore the improvement of the performance of heavy-haul railway subgrade, and ensure the overall stability of the subgrade, it is proposed to reinforce the subgrade soil with geosynthetic materials. The dynamic characteristics of plain soil and different reinforced soils were investigated by large-scale dynamic triaxial test.
Research conclusions: (1) The geogrids and geocells can significantly reduce axial deformation of specimens, with better performance observed in geocells.The amplitude has a greater influence on axial cumulative strain than confining pressure. The pore water pressure of specimens increases with the number of load cycles, showing three stages: slow growth, rapid increase, and gradual stabilization. (2) After reinforcement treatment with geogrids or geocells, the pore water pressure decreases significantly. (3) The stress-strain hysteresis loops under various conditions exhibit similar patterns characterized by initial dilatancy followed by compaction. (4) The damping ratio varies significantly among different specimens tested. Specimens reinforced with geocells have the lowest damping ratio while those reinforced with geotextiles have the highest damping ratio. (5) The research findings provide guidance on how to improve the dynamic characteristics of coarse-grained fill materials in heavy-haul railways.

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Preliminary Study on Unloading-collapsibility Characteristics of Inter-pile in Collapsible Loess Foundation

JIN Xin, WANG Tiehang, ZHAO Zaikun, ZHANG Meng, XUE Lei

Journal of Railway Engineering Society. 2025, 42(5): 7-12.

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Research purposes: To explore the unloading-collapsibility characteristics of loess between piles in collapsible loess composite foundations, this study establishes a computational model for unloading-collapse deformation of inter-pile loess by employing characterization parameters of the unloading-collapse process and a reduction equation for loess deformation modulus. The stress distribution and collapse deformation characteristics during the unloading-collapse process are analyzed, and new opportunities for engineering applications are broadened.
Research conclusions: (1) Vertical stress in inter-pile loess during unloading-collapse shows a decrease-increase-decrease trend, with diminishing reduction effect beyond critical pile spacing. (2) Accounting for unloading-collapse effects allows reducing neutral point depth, improving upon conservative traditional estimates. (3) The practice of blindly crossing or removing the collapse soil layer is economically inefficient. It is recommended to control collapse deformation of the site by adjusting pile spacing. (4) This study can provide a theoretical basis for support optimized stability assessment for high-speed rail subgrades in loess regions, enhancing cost-effectiveness and safety.

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Dynamic Numerical Analysis of Abutment Deflection Mechanism in Silt Stratum

YE Chaoliang, KONG Xiangkai, FENG Huaiping, MI Junfeng

Journal of Railway Engineering Society. 2025, 42(5): 13-19.

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Research purposes: The train dynamic loading effect is the main cause of bridge abutment deflection problems in soft foundations. To investigate the mechanism of bridge abutment deflection in silt strata under train loading,this paper establishes a three-dimensional dynamic numerical analysis model based on PLAXIS geotechnical software with the background of a bridge abutment deflection disease of Guangzhou-Zhuhai Railway. Considering the three stages and intermittent loading conditions before, during and after the arrival of the train, as well as the silt strength softening factors, the bridge abutment pile-soil force and deformation law is investigated to reveal the mechanism of bridge abutment deflection,to provide guidance for bridge abutment design and construction under similar geologic conditions.
Research conclusions: (1) During the three phases of the train passing through the bridge abutment, the horizontal displacement of the angular pile top at the front of the abutment (riverside) was the largest. Before arrival, the abutment deformation, silt excess pore pressure, and pile deformation were most significant during the decelerated braking condition. Upon arrival, the silt excess pore pressure, and pile horizontal displacement showed an increasing trend with decreasing strength of the silt soil layer. After passage, some residual excess pore pressure and pile plastic horizontal deformation remained and increased with decreasing strength of the silt layer. (2) Under train load intermittent action, with the increase of the number of loading and unloading, the pile top plastic horizontal deformation appears to accumulate, but the accumulation rate gradually slows down. The pile top cumulative plastic horizontal deformation increases with the decreasing strength of the silt layer, and the lower the strength, the faster the rate of change. (3) The cumulative plastic horizontal deformation of bridge abutment due to silt strength softening under train loading is the main factor triggering the bridge abutment deflection in silt strata. (4) This study has some reference value for the design and reinforcement of bridge abutments in the silt stratum.

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Research on the Reinforcement Effect of Straight-line Vacuum Preloading on Soft Soil Deposited by Volcanic Ash

SHEN Yupeng, LI Kang, ZHANG Qingbo, CUI Weixiao

Journal of Railway Engineering Society. 2025, 42(5): 20-25.

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Research purposes: The EMU depot of Jakarta-Bandung High-speed Railway is soft soil deposited by volcanic ash and its natural water content, pore ratio, and liquid-plastic limit are significantly higher than that of general soft soil. The poor engineering geological characteristics lead to the difficulty of subgrade stability and settlement control in this area. The conventional vacuum pressure method is used to treat long durations and large costs. To overcome the shortcomings of the above methods, this paper carries out a study on the applicability of straight-line vacuum preloading method for foundation treatment, comparatively analyses the characteristics of changes in soil physico-mechanical parameters before and after foundation treatment, and evaluates the reinforcement effect of straight-line vacuum preloading treatment for this type of soft soil.
Research conclusions: (1) The settlement rate on-site exceeded the 10 mm/d control standard required in the specification, but the soft foundation was stable after treatment. (2) During the straight-line vacuum preloading period, shallow soil is mainly subjected to surcharge preloading, resulting in significant outward displacement, with a maximum of 282.2 mm, while deep soil is subjected to vacuum preloading and undergoes inward displacement. (3) The average increase in cross-plate shear strength and static cone penetration resistance of the reinforced soil was 90.1% and 120.5%, respectively. In addition, there were significant improvements in physical and mechanical indicators such as natural moisture content, porosity ratio, and compression index. (4) The research results verified the suitability of inline vacuum pre-compression treatment for this kind of soft soil, which has important technical value and good economic benefits.

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Study on the Deformation Mapping Relationship of Long-span Bridges with Ballastless Tracks and Evaluation of Track Irregularity

CHEN Rong, LIU Kai, WANG Weiqin, XUE Min, ZHU Xiangyu, LV Tao

Journal of Railway Engineering Society. 2025, 42(5): 26-31.

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Research purposes: Long-span railway bridges exhibit significant flexibility and severe deflections deformation under extreme loads such as temperature variations. These deflections can cause geometric changes in the continuously welded rail tracks on the bridges, and influence the safety and quality of high-speed train operations. Therefore, it is crucial to study the deformation mapping relationship between long-span bridges and ballastless tracks, as well as to evaluate of track irregularity. In this study, a refined finite element model of a long-span cable-stayed bridge with ballastless tracks is established, a preliminary investigation into the deformation mapping relationship between the bridge and track is conducted under temperature load, and track irregularity is evaluated using the midpoint chord measurement method.
Research conclusions: (1) Under the combined effects of temperature and train loads, track vertical irregularities predominantly manifest as short-wave irregularities characterized by fastener spacing, such as 0.6 m and 1.2 m. (2) The maximum correlation coefficient between bridge vertical deformation and vehicle acceleration is observed at 0.12, whereas that between track vertical irregularity and vehicle acceleration peaks at 0.83. Furthermore, the correlation coefficient demonstrates an initial increase with extended measurement chord length, eventually stabilizing within the 40~60 m chord length range. (3) Irregularities are concentrated near bridge towers and piers, indicating that maintenance efforts should focus on these areas. (4) The research result can serve as a reference for evaluating track irregularity on long-span bridge structures.

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Research on Crack Propagation Law of CRTS Ⅲ Type Base Plate in Severe Cold Areas

CAI Xiaopei, DONG Bo, HU Yongli, FANG Taotao, YU Qiaosheng

Journal of Railway Engineering Society. 2025, 42(5): 32-37.

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Research purposes: In order to explore the crack characteristics of high-speed railway ballastless track base plate under frost heave in extremely cold regions, a crack propagation model for CRTSⅢ type base plate in the subgrade section was established based on the extended finite element method. The effects of frost heave position, amplitude, wavelength and existing cracks on the cracks of the base plate were studied. Meanwhile, the sensitive position of the base plate cracking was determined, and the crack propagation law of the base plate under various frost heave conditions was revealed.
Research conclusions: (1) The cracking of the base plate under subgrade frost heave is manifested as the lateral expansion of surface cracks, accompanied by a small amount of crack depth expansion in the later stage. When the frost heave effect is near the groove, the vertical depth of the crack is significantly larger than that of the frost heave effect in the non-groove area. (2) As the amplitude of frost heave increases, the transverse length of the crack rapidly increases and gradually stabilizes. (3) The increase of frost heave wavelength alleviates the local stress concentration of the base plate, effectively suppresses the crack propagation to the middle and depth of the base plate, and avoids the large vertical deflection angle of the crack. (4) When the transverse angle between the existing crack and the track plate is large, the propagation trend of the crack towards the middle of the base plate slows down. (5) The research results can provide a theoretical basis for the study of ballastless track cracks in severely cold areas.

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Study on Influence of Sleeper Bottom Texture on Ballast Lateral Resistance

QIANG Weile, CHENG Yan, LIN Mengmeng, JING Guoqing

Journal of Railway Engineering Society. 2025, 42(5): 38-42.

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Research purposes: The ballast lateral resistance is an important factor affecting the stability of CWR, an important basic parameter for the design and calculation of CWR of ballasted track, and also has an important impact on the safety and stability of train operation. In view of the insufficient depth of sleeper bottom texture in some areas, this paper conducts lateral resistance tests on sleeper with different texture conditions, studies the influence of sleeper bottom texture on the ballast lateral resistance, and discusses whether there is a possibility to cancel the relevant regulations of sleeper bottom texture in order to improve the construction efficiency.
Research conclusions: (1) The depth of sleeper bottom texture will have a certain impact on the lateral resistance of the ballast bed. The less depth of texture is, the smaller the lateral resistance of the ballast bed. (2) The overall texture is shallow, the texture part is shallow, the texture depth is enough but there is ash and slag in the sleeper compared with the ordinary Ⅲc sleeper, the lateral resistance of the track bed is reduced by 2.95%, 1.95%, 0.98%, and the influence range is between 0 and 3%. (3)The sleeper with shallow texture at the bottom will reduce the lateral resistance of the track bed, but the influence is not large. Under the same condition, the maximum dispersion of the repeated test results is more than 3%, which is similar to the influence amplitude of the texture. It can be concluded that the texture has little influence on the lateral resistance of the ballast bed. (4) In addition to the experimental study, a ballast-track discrete element simulation model should be established to analyze the influence of the depth of sleeper bottom texture on the lateral resistance of the track bed, and more accurate data should be used to verify the above conclusions.(5) Due to the small impact of concave patterns,it can be preliminarily considered to eliminate the relevant provisions of concave patterns.

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Seismic Design of Simple Supported + Rigid Frame Beam Bridge for Ballastless Track Railway

LIU Zunwen, LI Xinjing, CHEN Xingchong, HAN Guoqing, HAN Feng, LI Yuan

Journal of Railway Engineering Society. 2025, 42(5): 43-49.

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Research purposes: In the design of high-speed railway bridges in western China, simple supported + rigid frame beam bridges with double block ballastless tracks are used. Aiming at the seismic design problem of such bridge structures, the response spectrum method is used to study the seismic response of each structural system by establishing the traditional calculation model, the wire bridge integrated model considering only the constraints of the track system and the constraints of both ends of the rail, and adjusting the number of rigid frame bridge spans and pier heights for different gully areas.
Research conclusions: (1) The restraining effect of the track system and the rails at both ends reduces the seismic response of the pier, but the restraining effect of the track system in the main bridge area will increase the pier bottom bending moment of the rigid frame edge pier, while the restraining effect of the rails at both ends of the bridge is small. (2) In the wire bridge integrated model, the energy dissipation capacity of rigid frame pier will be enhanced with the increase of the number of rigid frame bridges, but with the increase of pier height, the main energy dissipation components will gradually change to rigid frame edge pier. (3) The restraint effect of the track system will inhibit the pier top displacement of the whole bridge, but with the increase in the number of rigid frame bridges, the restraint effect will be weakened. (4) When the main span rigid frame is in one or three joints, the track stress is in the shape of "V" and "U" respectively, and the peak stress is located in the beam joint of the rigid frame edge pier, special design is recommended here to deal with stress concentration. (5) The research results can provide a scientific basis for the seismic design of high-speed railway bridges in western China.

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Study on Wind Shear Hazard Control of Railway Bridge in Mountainous Area

ZHANG Yang, SU Guoming, GUO Xiangrong, XU Yong

Journal of Railway Engineering Society. 2025, 42(5): 50-55.

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Research purposes: To reasonably assess and ensure the operational safety of wind-train-bridge systems (WTBS) in mountainous areas, the present paper established a new numerical framework on the dynamic responses of WTBS incorporating wind barrier effects. The wind loads of this numerical framework are calculated via wind field characteristics at the bridge site, design reference wind speed at the bridge deck level, and the aerodynamic coefficients of both the bridge deck and train tested by large-scale sectional wind tunnel test. Based on this WTBS, we examined the dynamic responses and running performances of a C80-type freight train in an empty or loaded configuration operating at a speed of 50 ~ 100 km/h on railway bridges in crosswinds.
Research conclusions: (1) Installing wind barriers can effectively reduce the aerodynamic wind loads acting on the C80-type freight train, which plays an important role in ensuring the safety and stability of the train. (2) In the simply supported T-beam railway bridge segment, the maximum wind speed at the bridge deck level is 31.5 m/s. The freight train can safely run at its design speed in this crosswind, i.e., 80 km/h. (3) While in continuous rigid frame bridges and simply supported box-girder segments, the maximum wind speed at the bridge deck level is approaching 35 m/s. To ensure the freight train safely runs at its design speed in this crosswind, the wind barrier should be installed on both sides of the bridge. The recommended wind barrier parameters are 3.5 m in height and 60% in wind permeability ratio. (4) The present study finally gives reasonable technical parameters for wind barriers, speed limit thresholds, and implementation plans. These research results have significant theoretical significance and engineering reference value for the governance of wind shear hazards on mountainous railway bridges.

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Causes and Countermeasures of Tunnel Catastrophe in Water-rich Sandy Dolomite Stratum

WANG Zhijie, JIANG Yifan, XIAN Yiding, QI Yongli, LI Jinyi, ZHANG Huiling, ZHOU Ping

Journal of Railway Engineering Society. 2025, 42(5): 56-61.

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Research purposes: Dolomite sanding is a special karst phenomenon, which is highly disaster-causing in water-rich environments. To reveal the cause of disaster caused by tunnel surge in water-rich sanded dolomite stratum, the control measures are provided. Based on the Jixin Tunnel from the Emei to Miyi section of the Chengdu-Kunming Railway capacity expansion project, this paper investigates the tunnel surge accident, analyzes the formation causes of white cloud sand by combining regional geology, indoor microscopic observation methods, and physical and mechanical tests, summarizes the disaster mode and causes of sanded dolomite, and puts forward control measures.
Research conclusions: (1) The regional dolomite sanding mechanism is a permeation-dissolution decomposition mechanical disintegration type, and the water-rich sanding sacs distributed in the formation are the disaster source of tunnel gushing. (2) Sanded dolomite is dominated by fine particles, poor uniformity, and significantly attenuated shear strength in water. Tunnel surge failure modes can be divided into penetration-type surge, progressive surge, and intermittent surge. (3) The disaster source identification, disaster source water pressure reduction, disaster source reinforcement, low disturbance excavation construction control countermeasures are proposed.(4) The research results can be applied to the control of tunnel water outburst disasters in sanded dolomite formation.

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Theoretical Analysis of Longitudinal Seismic Response of Tunnels Crossing Active Faults

YUAN Jinxiu, ZHU Zhengguo, ZHANG Haotian, WANG Daoyuan, HUI Yunjie, MA Jiwen, SONG Baolu, GUO Yingchun

Journal of Railway Engineering Society. 2025, 42(5): 62-68.

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Research purposes: The damage to tunnel structures under earthquake action mainly occurs in fault sections. To study the longitudinal earthquake response characteristics of cross fault tunnels under earthquake action, firstly, based on the Pasternak dual parameter elastic foundation beam theory, a mechanical model for the longitudinal earthquake response of cross fault tunnels was established and theoretical analytical solutions were obtained; Secondly, the rationality of the theoretical solution was verified by using numerical calculation methods; Finally, the dynamic response laws of structural stiffness, wave velocity ratio, and fault width on the displacement and internal forces of tunnel structures were discussed.
Research conclusions: (1)The longitudinal earthquake response mechanical model of the cross fault tunnel is reasonable, and the maximum error of the theoretical solution does not exceed 3%, which can be applied to practical engineering design. (2) The increase in structural stiffness reduces the displacement of the lining within the fault range and increases the internal force of the structure.(3)The displacement and internal force of the lining show an increasing trend with the increase of wave velocity ratio.(4)The increase in fault width increases the displacement of the lining and reduces stress concentration.(5)In practical engineering, it is recommended to use gradient grouting method to reinforce the rock mass near the fault width of 4~5 times, in order to improve the anti fault ability of cross fault tunnels. (6)The research conclusion can provide theoretical basis for seismic design of cross active fault tunnels.

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Longitudinal Deformation Profile Analysis of TBM Circular Tunnel Considering the Influence of Surrounding Rock and Support Stiffness

ZHU Baoqiang, SHI Yipeng, YU Xiaoxuan, PENG Hao, GUO Fawang, SHEN Chunyong, ZHOU Haizuo

Journal of Railway Engineering Society. 2025, 42(5): 69-76.

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Research purposes: The longitudinal deformation profile is an important part of the convergence-confinement method, and it can reflect the radial displacement development of tunnel surrounding rock during excavation. However, most of the current studies are based on elastic and elasto-plastic theory or based on specific engineering monitoring data to fit the longitudinal deformation curve, lacking consideration of different surrounding rock quality and support conditions, resulting in limited scope of application. In this paper, the numerical simulation is used to construct the tunnel excavation deformation database. The multiple regression model is used to establish the longitudinal deformation expression of the tunnel which can quantify the spatial effect of the excavation face under different surrounding rock mass and annular lining support stiffness. The accuracy and superiority are verified based on error analysis and engineering measured data.
Research conclusions: (1)For the ahead and behind of the tunnel face, the development rate of the longitudinal deformation curve of the tunnel decreases significantly with the decrease of the support stiffness when the quality index of the surrounding rock is the same. When the supporting stiffness remains unchanged, the development rate of longitudinal deformation profile of tunnel increases obviously with the decrease of surrounding rock quality index. (2)The normalized radial displacement deformation value at the tunnel face is a function of surrounding rock mass and support stiffness, and also increases significantly with the decrease of surrounding rock mass index value and the increase of support stiffness. (3)The analysis of the fitting formula shows that the normalized radial displacement value at the tunnel face is more sensitive to the change of the surrounding rock mass index value in the two factors. (4)The research outcomes presented in this paper can be effectively applied in tunnel engineering practice. By establishing response surfaces under varying surrounding rock quality and support stiffness conditions, they can provide guidance for preliminary on-site design.
Key words: longitudinal deformation profile; surrounding rock quality; tunneling engineering; support stiffness; multi regression model

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Evaluation System of Large Deformation Grading for Large Depth and High Stress Tunnels

JIANG Jing

Journal of Railway Engineering Society. 2025, 42(5): 77-82.

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Research purposes: Classification and prediction of large deformation is one of the key points in the study of large deformation in tunnels. Through statistical combing of 72 cases of large deformation of domestic and foreign deep tunnels, 12 evaluation indexes in four aspects of stress conditions, mechanical characteristics of the surrounding rock, groundwater, and rock yield are selected to construct a large deformation grading evaluation system for large deep and high stress tunnels, and a tunnel of the Chengdu-Lanzhou Railway is used as a case study for analysis and verification, and finally 15 tunnels with significant deformation characteristics are selected for comparison and analysis of the evaluation method proposed by the present study with the existing large deformation prediction methods.
Research conclusions: (1) The prediction result of the large-deformation grading evaluation system for large-deep and high-stress tunnels is 93.3%, which can effectively predict the degree of large deformation of tunnels. (2) The method transforms the process of qualitative analysis into the calculation of quantitative indexes, which contributes to the scientific development of the prevention and control measures of tunnel deformation, and the establishment of the evaluation system also can provide reference for the subsequent similar projects.

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Study on Structural Deformation Effects of Adjacent Stations Induced by PBA Subway Construction

LIU Minghui, JIA Siyi, BU Yu

Journal of Railway Engineering Society. 2025, 42(5): 83-89.

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Research purposes: In the context of massive construction of urban rail transit and the limited urban underground space, the adjacent and intersecting construction is getting ubiquitous between lines and stations, and the impacts of new construction on adjacent structures are becoming prominent. This paper researches the impacts of new subway stations built by the PBA method on the deformation of adjacent existing structures. A finite element model of the new station and existing station is established, and the simulation results of ground deformation during the construction are compared with measurements.
Research conclusions: (1) The adjacent station structure undergoes settlement deformation in the vertical direction and lateral deformation towards the newly constructed station in the horizontal direction. The pilot tunnel excavation and arch enclosure construction stages are identified as the primary phases of structural deformation accumulation, with numerical calculations aligning well with field measurements. (2) During construction, the track irregularity of the existing station demonstrates a fundamentally linear correlation with structural deformation. (3) Stepwise control criteria for structural deformation have been established based on the displacement distribution control principle. (4) The conclusions derived from this study provide practical guidance for subsequent similar engineering constructions.

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TOD-X: AI-Driven Integration and Application of TOD Theory

BAI Liwei, WANG Tao, LI Chaoyang, ZHANG Yi, YANG Zheng, FENG Yichen

Journal of Railway Engineering Society. 2025, 42(5): 90-97.

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Research purposes: With AI technology accelerating transformations in urban planning, the dissolution of information silos and the integration of interdisciplinary theories have become research focuses. This study addresses the application adaptability of Transit-Oriented Development (TOD) and identifies challenges in conceptual clarity, methodological innovation, evaluation standards, knowledge transfer, and research perspectives. To tackle these issues, this paper proposes the TOD-X theoretical framework, which integrates core TOD theories with derivative models and incorporates AI technologies to optimize its adaptability, offering new pathways for sustainable urban development.
Research conclusions: (1) The TOD-X framework provides the following advantages:enhances the adaptability of theory to practice through modular design; integrates diverse demands to broaden research perspectives and policy support; leverages AI to strengthen data processing and resource allocation;offers intelligent and context-specific decision support tailored to varying urban scenarios. (2)This study can present an innovative theoretical tool and practical paradigm for advancing sustainable development in transit-oriented cities.

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Performance Test of Recycled Aggregate Concrete Modified by Hybrid Fiber and Silica Sol

WANG Xingguo, LIU Zhixuan, WANG Yonggui, JIANG Maolin, SONG Guangming, CHENG Zhaoxia

Journal of Railway Engineering Society. 2025, 42(5): 98-103.

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Research purposes: The inferior interfacial transition zone (ITZ) and microporous structure of recycled aggregate concrete (RAC) compromise its mechanical performance, jeopardizing structural safety and durability. In order to investigate the effect of the concentration of nano-SiO₂ solution on the pre-soaking of recycled aggregates, the amount of steel-polyvinyl alcohol (PVA) fibers on the mechanical properties of recycled aggregate concrete, it was proposed to use orthogonal test to design 16 groups of nano-SiO₂ modified aggregate-steel/PVA fiber recycled aggregate concrete specimens to test the effect of factors on its compressive strength and splitting tensile strength influence law.
Research conclusions: (1) Fiber incorporation improves the stress distribution within RAC, enabling post-failure specimens to retain partial structural integrity. (2) Nano-SiO₂ solution enhances ITZ performance in RAC, optimizing internal compactness. (3) Steel fibers exhibit the most significant positive influence on compressive and splitting tensile strengths, whereas PVA fibers contribute marginally. Conversely, higher substitution ratios of recycled coarse aggregate negatively affect both mechanical properties. (4) The proposed predictive model for nano-SiO₂-modified steel/PVA fiber RAC strength parameters provides practical guidance for engineering applications.

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Experimental Study on Waterproof Material for Construction Joint of Lining of Tunnel with Mining Method

HE Yongyi, SHANGGUAN Yuwen, LIU Dagang, WANG Yangyang, WANG Zhilong, WANG Mingnian

Journal of Railway Engineering Society. 2025, 42(5): 104-108.

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Research purposes: At present, the waterproofing problem of the secondary lining circumferential construction joint mainly adopts the medium-buried waterproof material. However, during the construction process, problems such as twisting, floating, displacement and tipping of the waterstop often occur, making it difficult to ensure the construction quality. Therefore, this article adopts indoor experimental methods to study the waterproof effects of two new waterproof materials, cement-based permeable crystalline waterproof coating and non-oil permeable creep rubber waterproof coating, on the construction joints of the secondary lining of mining tunnels.
Research conclusions: (1) The type of waterproof coating and application method is closely related to the hydraulic strength, and need to be based on the hydraulic strength of reasonable choice. (2) Dust will affect the adhesion of waterproofing coatings and substrates, there is a dusty situation will significantly reduce the waterproofing performance. (3) Chiseling process on the non-oil-permeable creep rubber waterproofing coatings construction joints of impermeable performance of the influence of a small.(4) The research results can provide a reference for the development of waterproofing technology for the tunnel of the mining method as well as the control of the safety of tunnel support structure.

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Research on the Compilation Method of Railroad Project Cost Index Based on Elastic Network Regression

GUO Jingjuan, ZHANG Zhengwen, GAO Zhenji, LI Bin

Journal of Railway Engineering Society. 2025, 42(5): 109-115.

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Research purposes: At present, China's railroad projects are mainly based on fixed prices, and the fixed price has a certain lag in response to the market environment and price fluctuations. The cost indexes obtained by analyzing the actual data of the project and the market can not only provide the time-sensitive market reference price, but also the data structure is more suitable for the informatization management of the cost. The purpose of this paper is to analyze the influencing factors of railroad project cost, establish the prediction model of railroad project cost, and put forward a method of compiling the railroad project cost index, to provide a theoretical basis and reference method for the establishment of market-oriented management mode of railroad project cost and the improvement of information management level.
Research conclusions: (1) Through literature research, survey research, and gray correlation analysis, the main engineering characteristic variables affecting the cost of railroad projects are derived. (2) The elastic network regression method is applied to establish the prediction model of railroad project cost, and the prediction error is less than 8% in the example validation, and the prediction goodness of fit is good. (3) By applying the railroad project cost prediction model based on elastic network regression, the railroad project cost indexes can be compiled in different periods and under different project characteristics, and can also be expanded to the compilation of corresponding project cost indexes based on construction drawing budgets and bidding quotations.

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Analysis and Optimization of Resource Input Output Efficiency of Beijing-Tianjin-Hebei Railway

ZHANG Xinning, CHEN Shiyu, LIU Na

Journal of Railway Engineering Society. 2025, 42(5): 116-121.

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Research purposes: Based on the relevant railway data of the Beijing-Tianjin-Hebei region from 2018 to 2022, this paper conducts static and dynamic analyses using the Malmquist index and DEA model. With the rationality of resource allocation and the balance of input and output as the research purpose, it analyzes the changes in the efficiency indicators of railway resource input and output in the Beijing-Tianjin-Hebei region and analyzes input redundancy and output insufficiency. Then, the data is adjusted to reach the optimal state. This research has significant theoretical and practical value for the optimization of railway resources in the Beijing-Tianjin-Hebei region and the coordinated development of the region.
Research conclusions: (1) Based on the DEA-BCC model, from three perspectives and with the introduction of slack variables, it is found that there will be insufficient passenger turnover and cargo turnover in Tianjin Railway in 2018 and redundant railway transportation employees in Beijing Railway in 2019-2021; Based on the dynamic analysis of Malmquist model, it is found that the decline of total factor productivity in the Beijing-Tianjin-Hebei region is mainly determined by scale efficiency. (2) Because of the above problems, two suggestions are put forward to realize the complementary advantages of the Beijing-Tianjin-Hebei region and promote the flow of people in the Beijing-Tianjin-Hebei region.(3) The results obtained by combining precise data with empirical analysis apply to the application field of optimizing the allocation of railway resources in the Beijing-Tianjin-Hebei region.

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15 May 2025, Volume 42 Issue 5

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15 May 2025, Volume 42 Issue 5