Research purposes: Water-rock coupling threatens the long-term stability of underground oil storage facilities in mountain area. Surface runoff infiltration accelerates rock damage and deformation, compromising construction safety. Therefore, characterizing fractured rock mechanics under varying saturation levels and developing a constitutive model for water-induced damage evolution is essential. This provides a theoretical basis for designing targeted reinforcement and adaptive support strategies.
Research conclusions： (1) Sandstone's uniaxial compressive strength and elastic modulus decrease approximately linearly with increasing saturation with a softening coefficient of approximately 0.37. (2) Higher saturation shifts the failure mode from brittle single-crack shear to ductile multi-crack distributed shear. (3) Saturation dictates energy evolution: it alters pre-peak energy distribution and crack propagation, while regulating post-peak energy release via pore-water pressure. (4) The proposed statistical damage model accurately captures the rock's mechanical response, demonstrating that elevated saturation significantly increases initial damage and accelerates its evolution. (5) The research findings can provide theoretical support and parameter guidance for the excavation and support design of underground engineering in water-rich strata.

Research purposes: Layered surrounding rock is prone to flexural and shear failure along bedding planes, accompanied by progressive interlayer failure propagation. However, a quantitative understanding of how rockbolts control the failure extent and pressure-arch evolution remains lacking. Taking gently inclined horizontal layered rock as a typical subject, this study establishes mechanical models for rock beams and arching blocks incorporating bolt constraints, proposes failure criteria for individual layers, interlayer connection conditions, and failure termination criteria, and thereby develops a prediction method for the collapse extent of bolt-reinforced layered rock. Physical model tests and numerical simulations are conducted to analyze the progressive failure process, pressure-arch evolution, and stress redistribution, and to verify the reliability of the proposed method. The findings provide a theoretical basis for collapse prediction and the quantitative design of rockbolt support in tunnels within gently inclined layered strata.
Research conclusions：(1) Failure of layered surrounding rock may initiate from flexural-tensile or shear failure of a single rock layer and then propagate progressively into the surrounding rock through the continuous connection of failure zones in adjacent layers. Failure propagation terminates when the failure widths of adjacent layers no longer satisfy the continuity condition. On this basis, the collapse boundary and collapse height of layered surrounding rock can be determined. (2) The theoretical predictions obtained using the proposed method agree well with the numerical simulation results. Moreover, the difference between the theoretical calculations and physical model test results gradually decreases with increasing load, indicating that the method has good predictive capability for the failure extent above the tunnel crown in rockbolt-reinforced layered surrounding rock. (3) Rockbolt support effectively suppresses progressive failure and the expansion of the collapse zone in layered surrounding rock. No obvious collapse occurred in the rockbolt-reinforced case under loads ranging from 30 kPa to 120 kPa. At a load of 150 kPa, the collapse height decreased from 21.5 cm in the unreinforced case to 11.2 cm in the reinforced case, corresponding to a reduction of approximately 47.9%. (4) Rockbolt support makes the circumferential stress distribution around the tunnel more uniform and reduces the maximum circumferential stress by 10.4%-35.3% under different loading levels compared with the unreinforced case. Meanwhile, rockbolts reduce stress concentration at the tunnel haunches, restrain the pressure arch from extending into the deeper surrounding rock, and promote the formation of a relatively stable load-bearing structure near the tunnel boundary. (5) The results can provide a theoretical basis for predicting the failure extent, optimizing rockbolt-support parameters, and quantitatively designing support structures for tunnels in gently inclined layered surrounding rock.

Research purposes: For subgrades with deep beaded karst development, the differences in embedded rock depth and base slab thickness specified by various codes increase the difficulty of design. To study the rational design parameters of the embedded rock depth and base slab thickness for pile-plate structures under the development characteristics of deep beaded karst caves, this research is based on a pile-plate structure project for a high-speed railway subgrade in a deep beaded karst area to explore the pile bearing capacity under different embedded rock depths, as well as the characteristics of post-construction settlement of the subgrade, punching shear resistance, and shear stability under different base slab thicknesses. Key design parameters such as embedded rock depth and base slab thickness are proposed for deep beaded karst development conditions.
Research conclusions： (1) An embedded rock depth of 0.5 m is sufficient to meet the bearing capacity requirements of the foundation, which is less than the requirement stipulated in the Code for Design of Special Railway Subgrade that "the pile tip should penetrate the karst cave and extend into the stable bedrock by not less than 1.5 times the pile diameter". (2) For the selected load-bearing rock layer, priority should be given to ensuring the thickness of the base slab at the pile bottom, with a relatively small embedded rock depth. (3) When the karst cave below the pile tip is filled with soft soil, the thickness of the base slab should not be less than 3d (where d is the pile diameter), which is consistent with the provisions of the Technical Code for Building Pile Foundations. As the karst cave is filled with silty clay mixed with gravel, medium-coarse sand, or gravel, the thickness of the base slab should not be less than 1 m, which is less than the base slab thickness required by the Code for Design of Special Railway Subgrade. (4) The findings of this study can serve as a reference for the selection of design parameters for pile-slab structures in railway subgrade in karst regions and for the revision of relevant specifications.

Research purposes: With the continuous increase in the operating speed of maglev trains, the "beam-track integration" design has exposed problems such as difficult construction adjustment, poor economic performance, and difficulty in satisfying the geometric smoothness requirements for higher operating speeds. To meet the engineering application requirements of a 600 km/h high-speed maglev system, this paper proposes a new technical solution of "beam-track separation" track system, defines the track structure type and key dimensions, and analyzes the static characteristics and dynamic responses of the track under typical loads.
Research conclusions：(1) Static analysis demonstrates that the structural strength of the new track system under train loads and temperature effects satisfies the design requirements for high-speed maglev applications. (2) Dynamic analysis indicates that the proposed track system provides a smooth and stable running surface for maglev trains, with minimal dynamic responses. Both safety and stability indices are below the specified limits. (3) The results of this research can provide references and insights for the design of high-speed maglev railway system.

Research purposes: The control of track vertical smoothness on high-speed railway large-span bridges is critical for ensuring smooth and comfortable driving. Traditional vertical smoothness measurement methods cannot conduct multi-point joint measurement at the same time during high-speed railway operation and timely evaluate the status of track vertical smoothness. To meet the needs of real-time monitoring and evaluation of track alignment of 300 m long-span bridges and to verify the feasibility of image recognition technology in the monitoring of track alignment of long-span bridges, this study developed intelligent monitoring equipment for vertical smoothness using visual measurement and edge computing methods. Through multi-feature fusion-based signboard recognition and coordinate algorithm, overlapping and orthogonal target feature points were introduced into image splicing calculation and image orthogonal transformation calculation respectively, realizing the analytical calculation of linear coordinates from image sequences of multiple devices, and finally building a real-time monitoring system for vertical smoothness, and conducting evaluation of track vertical smoothness.
Research conclusions：(1) The intelligent monitoring equipment for track smoothness provides millimeter-scale vertical displacement measurement accuracy over a 70 m range. (2) On-site measurements from January to November show that the maximum track elevation deviation on 300 m large-span bridges is 26.38 mm. The deviation is larger at lower temperatures and smaller at higher temperatures. (3) Locations with poor track vertical smoothness are near the bridge tower and the midspan. The maximum calculated value of the 60 m chord at the bridge tower is 5.75 mm, and the maximum absolute value near the midspan is 5.34 mm. Both values are less than the 7 mm limit for static track acceptance, indicating generally good vertical smoothness. (4) This study can provide technical reference for the design and optimization of track alignment monitoring schemes.

Research purposes: Kilometer-scale long-span bridges are characterized by high structural flexibility and significant overall deformation, resulting in more complex alignment variations compared with conventional medium and small-span bridges. The current domestic design specifications are mainly formulated based on conventional bridges and exhibit poor adaptability to the deformation characteristics of kilometer-scale bridges, lacking targeted limit requirements for longitudinal profile design parameters. Based on the Shanghai-Suzhou-Nantong Yangtze River Bridge and Wufengshan Yangtze River Bridge, both with a main span of 1 092 m, this paper systematically investigates the design principles and evaluation methods for the longitudinal profile of kilometer-scale bridges, with a focus on the value determination of core parameters, including vertical curve radius, gradient, grade segment length, and the limiting gradient for passenger-freight mixed railways.
Research conclusions：(1) The vertical curve radius has a significant influence on the vertical acceleration of the vehicle body. The acceleration tends to be stable when the radius is no less than 30 000 m, which is approximately 0.2 m/s² for the Wufengshan Yangtze River Bridge and 0.1 m/s² for the Shanghai-Suzhou-Nantong Yangtze River Bridge. (2) Considering the performance of rail expansion joints and the deck drainage requirements, the herringbone slope gradient of high-speed railways should not be greater than 12‰. (3) When the gradient segment length is no less than 200 m, the vibration superposition effect between adjacent vehicle bodies disappears and the acceleration stabilizes, so it is recommended that the minimum gradient segment length should be greater than 200 m during gradient adjustment. (4) For mixed passenger and freight railways, a design gradient of no more than 4‰ can ensure that the comprehensive dynamic gradient under the most unfavorable load combination does not exceed the code limit of 6‰. (5) The research achievements provide technical support for follow-up kilometer-level long-span bridge construction, and promote the further advancement of long-span bridge construction technology in China.

Research purposes: Current research on vehicle-bridge coupled vibration of deck arch bridges under double-line train meeting conditions remains insufficient. Specifically, the influence patterns of meeting locations on system dynamic response and the identification of the most unfavorable positions have not been systematically revealed.
Research conclusions：(1) The Pseudo-Excitation Method effectively circumvents the result dispersion caused by phase angles in traditional stochastic analysis. The model validation shows good agreement with literature results, confirming the reliability of the method. (2) The meeting position at 3L/8 is identified as the most unfavorable location for running safety. At this position, the car body acceleration (1.22 m/s²) increases by 37.1% compared to the minimum value at the mid-span (0.89 m/s²), and the wheel load reduction rate (0.501) increases by 2.5% compared to the average value at other positions (0.489). (3) The meeting position at the mid-span (4L/8) is the most unfavorable location for the bridge structure. The vertical displacement (14.4 mm) increases by 61% compared to the average of other positions (8.95 mm), and the acceleration (0.515 m/s²) increases by 50.1% compared to the average of other positions (0.343 m/s²). (4) An increase in train speed significantly amplifies the dynamic response of both the vehicle and the bridge. Specifically, the car body acceleration, wheel load reduction rate, bridge displacement, and acceleration increase by 15.6%, 22.0%, 14.6%, and 22.3%, respectively. Conversely, when adopting the Chinese track spectrum, the aforementioned indicators decrease by 37.7%, 43.3%, and 41.8%, respectively, with a marginal increase of 0.7% observed in bridge displacement. (5) These research findings provide a theoretical basis for the safety assessment of double-line train meetings on deck-through arch bridges.

Research purposes: With the rapid development of transportation infrastructure in China, rail-cum-road bridges with highway and railway on the same level offer significant advantages in saving land resources. However, this unique structural form introduces a series of safety issues arising from operational interference between the highway and railway. Currently, there is a lack of systematic discourse and solutions for traffic safety protection technologies specific to such long-span rail-cum-road bridges globally. Based on the pioneering Yibin Lingang Yangtze River Bridge, this paper systematically studies the critical risks present during operation, including glare, noise, aerodynamic impact, collision, and object intrusion. The goal is to develop an integrated and cost-effective technical system for traffic safety protection to ensure the operational safety and efficiency of both the highway and railway.
Research conclusions：(1) The mechanism of strong glare induced by high-speed train lights on highway drivers is revealed. A quantitative relationship model between illuminance, distance, and angle is established for the first time through field tests. The threshold increment (TI) is determined to reach up to 303% under the most adverse conditions, and the reasonable height of the anti-glare panel for the project is determined, achieving precise control of the glare effect. (2) A multifunctional integrated isolation device combining noise reduction and wind shielding is developed. Driving simulator experiments quantify the impact of noise on driver behavior, achieving a noise reduction of 7.7 dB(A) and effectively mitigating the aerodynamic effects and noise disturbance from passing trains. (3) A high-level double-layer guardrail system is proposed for conditions where the parallel spacing between highway and railway is less than the code-specified limit, ensuring the operational safety of both highway and railway. (4) An intelligent perimeter intrusion detection system integrating "vibration optical fiber + video surveillance + AI recognition" is constructed for the first time specifically for parallel rail-cum-road bridges. By fusing multi-source sensing technologies, it enables real-time detection, intelligent identification, and rapid warning of intrusion behaviors such as climbing, destruction, and impact. (5) This integrated set of technologies has been successfully applied to the Yibin Lingang Yangtze River Bridge, forming a complete safety assurance system. It provides a vital and replicable reference for the design, construction, and operation of future long-span same-level rail-cum-road bridges in China and abroad.

Research purposes: On July 12, 2025, a high-water-pressure and large-flow water and mud inrush occurred at the DK380+541 face of the Zhaotong Tunnel on the Chongqing-Kunming High-Speed Railway, characterized by abruptness and strong destructiveness. Field exposure revealed that this disaster was primarily controlled by a vertical dilatancy crack. Based on geological survey, construction exposure records, hydrological monitoring, and fluid-solid coupling numerical simulation, this study systematically analyzes the crack development characteristics, water source recharge conditions, and construction disturbance effects, reveals the evolution law of the disaster chain, and provides a scientific basis for risk prevention in tunnel engineering under similar geological conditions.
Research conclusions： (1) The vertical dilatancy crack is the key controlling structure for this water inrush. Intersecting the tunnel at a small angle, it features high porosity, low strength, and high permeability, constituting the main channel for groundwater storage and rapid migration in deep slow-flow zones. (2) The water-inrush mechanism follows a chain process of "cavity water accumulation-water head rise-instantaneous outburst": excavation disturbance induces instability of the crack free face and cavity formation; cavity opening blockage causes a sharp increase in internal water pressure, triggering high-pressure hydraulic fracturing and instantaneous outburst. (3) The strongly karstified surface area provides a stable high-pressure water source for the fracture. (4) The research results can be applied to guide advanced geological prediction, risk identification, and emergency prevention in tunnel engineering under similar geological conditions.

Research purposes: China's urban underground spaces have largely entered the maintenance stage, facing challenges such as unclear strengthening mechanism of lining structures and inability to accurately define their bearing capacity after strengthening. These issues result in a significant disconnection between the theoretical basis for underground space structure strengthening and the actual engineering needs. Based on theoretical analysis, this paper deduces a bearing capacity calculation model of the composite sleeve lining tunnel structure strengthening system under normal service conditions, and reveals the variation law of the bearing capacity of the composite sleeve lining structure system as well as its main influencing factors, thereby providing theoretical support for the rehabilitation of underground space structures.
Research conclusions： (1) With the increase of the thickness of the newly added composite lining, the height of the compressed zone of the section and the cracking moment both increase correspondingly. (2) As a typical bending-compression member, to avoid the sudden change of the effective compressed zone height of the section and the transformation of the bottom of the existing lining structure from the tensile zone to the compressed zone, the thickness of the newly added composite lining should not exceed 70% of the thickness of the original section. (3) With the increase of the thickness of the newly added composite lining, the section moment corresponding to the ultimate crack width increases gradually, showing a monotonically increasing positive correlation between the two. (4) With the increase of the thickness of the newly added composite lining, the growth rate of the section anti-cracking moment is significantly greater than that of the moment corresponding to the ultimate crack width, and the increase of the thickness of the composite lining is more conducive to inhibiting the occurrence of cracks on the tensile side of the lining. (5) The research conclusions can provide reference for the strengthening of underground space structures.

Research purposes: Local small-scale pressurized gas pockets have been predicted in the East Qilian Mountain Tunnel of the Xining-Chengdu Railway during the geological investigation phase. To address the construction safety challenges arising from high-pressure CO₂ gas emissions in the tunnel, this study investigates the CO₂ gas monitoring, prevention, and control technologies for the tunnel, providing a reference for the design of similar projects, and the research findings are expected to be incorporated into industry specifications.
Research conclusions： (1) Based on the four-level CO₂ gas risk classification criteria (extreme, high, medium, low), tunnel sections are precisely delineated according to their risk levels. (2) A multi-dimensional monitoring mode integrating automatic and manual monitoring, advanced detection and process monitoring, as well as concentration monitoring and flux testing is established, which enables the real-time and accurate tracking of dynamic variations in CO₂ gas concentration. (3) For tunnel ventilation in high-altitude areas, the design parameters for required air volume and air pressure require elevation correction. The selection of high-efficiency axial flow fans and large-diameter air ducts, combined with layout optimization, ensures ventilation efficiency. (4) Technical schemes adapted to different risk levels are formulated for structural sealing, surrounding rock grouting, centralized drainage and ventilation optimization, and a comprehensive technical system for CO₂ gas prevention and control is constructed. (5) Research findings can provide references for the design of similar tunnels containing hazardous gases.

Research purposes: The increase in train operational speed from 350 km/h to 400 km/h in open-cut tunnels of China's high-speed railways faces the challenge of intensified environmental vibration around the tunnels. This study establishes a refined coupled dynamic response model for the open-cut tunnel and surrounding strata, conducts field tests based on an actual project to verify the accuracy of the computational model, and further investigates the environmental vibration characteristics around urban open-cut tunnels for 400 km/h high-speed railways, exploring vibration mitigation measures for open-cut tunnels along with the influence of key design parameters on their mitigation effectiveness.
Research conclusions：(1) When the train operational speed increases from 350 km/h to 400 km/h, the environmental vibration around the open-cut tunnel significantly intensifies, with the maximum Z-vibration level at a ground point 30 m from the track centerline increasing by approximately 2.4 dB. (2) The environmental vibration energy induced by train operation in the 400 km/h open-cut tunnel is primarily concentrated in the frequency bands of 10 Hz-20 Hz and 40 Hz-60 Hz. (3) Foundation piles for the open-cut tunnel can significantly attenuate the transmission of vibration waves in the 8 Hz-80 Hz frequency band to the surrounding environment. Increasing the pile diameter, pile length, number of piles per row, or decreasing the row spacing between piles can enhance the vibration mitigation effectiveness of the foundation piles. (4) Installing a rubber-like elastic layer outside the waterproofing layer of the open-cut tunnel can reduce the environmental vibration induced by train operation, with the primary mitigation frequency band being 1 Hz-80 Hz. The most pronounced vibration reduction is achieved when the elastic layer is installed on both sides of the tunnel structure. (5) The research findings can provide reference and guidance for the route selection and vibration mitigation design of urban open-cut tunnel engineering for 400 km/h high-speed railways.

Research purposes: Railway power electrification design has long followed the "3D modeling-first" paradigm of civil engineering. In practice, however, this paradigm fits the discipline poorly: electrification design assembles discrete equipment rather than shapes continuous geometry, so efficiency gains have been limited, core engineering data remain constrained by proprietary formats of commercial software, and data handover among design, construction and operation is still difficult. Grounded in the discipline's "data-as-design" nature, this paper reconstructs the forward design paradigm and methodology along a data-centric route of "design intent-structured data-3D model", in which design outcomes are delivered in open formats and remain under the design institute's own control.
Research conclusions：(1) A "Data-Defined Model" forward design paradigm is proposed, shifting railway electrification digitalization from model-centric to data-centric. (2) This study establishes a technical pathway integrating homologous 2D/3D data, data-driven logic, and automated 3D generation. A theoretical model that maps design intent to structured data and subsequently to 3D models, along with a data-model loose-coupling architecture,is implemented. Engineering validation confirms a reduction in the design cycle of over 30%. (3) A digital delivery system is developed based on XML/JSON open formats, resolving data sovereignty issues caused by proprietary commercial software formats. The research results have also supported the drafting of the Railway Engineering Digital Delivery Standards. (4) These findings provide theoretical foundations and engineering references for digital and intelligent design of railway electrification and BIM-based forward design.

Research purposes: To address the issues in the operation and maintenance of electrified railway catenary systems, such as low recognition rates for fault/defect images, inaccurate remaining life predictions for critical components, data silos caused by the fragmented "operation-inspection-maintenance" process, and the high risks and low efficiency of manual maintenance, this paper aims to establish an "Inspection-Evaluation-Repair integrated system", and develop a comprehensive self-propelled mobile platform and equipment that combines these three functions, thereby providing core technical support for the intelligent upgrading and efficient operation and maintenance of rail transit catenary systems.
Research conclusions：(1) An innovative "cloud-edge-end" collaborative architecture is proposed to break down multi-source data interaction barriers, address the fragmentation of traditional "inspection-evaluation-maintenance" processes, and drive the transition of the operation and maintenance model from passive maintenance to active prediction. (2) A defect recognition algorithm based on improved YOLO is proposed, achieving a 100% accuracy rate in identifying critical catenary defects. The "macro-precise-micro" three-level positioning and multi-robot collaborative control technology are introduced, enabling multi-level progressive assurance of operation precision and automated collaborative operations. (3) A modular self-propelled operation and maintenance vehicle group is developed, integrating high-precision and efficient detection and monitoring equipment, maintenance robots, and high-precision positioning and alignment devices for the vehicle group, significantly improving operation accuracy and efficiency compared to traditional manual methods. (4) The intelligent self-propelled operation and maintenance system demonstrates broad applicability and can be effectively applied to the operation and maintenance of high-speed railway and urban rail transit catenary systems, providing key equipment support and technical solutions for transportation development strategy.

Research purposes: To address the difficulties of "impossible to demolish, no space to arrange, and unable to approach" faced in the construction of open-cut metro stations in complex urban environments, this paper proposes a double-split circular shield station design scheme based on vertical traffic core, using an actual project as the background. It focuses on a systematic analysis of the cross-sectional form, architectural functional layout, adaptability, and internal structure prefabrication of shield stations, aiming to provide references for similar projects.
Research conclusions： (1) The proposed double-split circular shield tunnel with a central vertical transportation core provides a compact, functionally integrated shield station design that streamlines both station operations and construction procedures. (2) Through cross-sectional optimization measures such as integrating pipelines into the under-platform corridor space, the inner diameter of the double-split circular shield station tunnel can be effectively controlled at 8.4 m. (3) Through adaptability analysis and verification, the shield station can meet the functional requirements in terms of side platform width, fire evacuation, and daily passage. (4) The prefabrication scheme of the internal secondary structure in the shield station can effectively solve the problems of limited space and long construction period in the shield tunnel, and achieve rapid, lightweight, and low-labor on-site operations. (5) This research provides technical basis and design references for the application of double circular shield stations.

Research purposes: In the metro industry, the typical problems of excessive rail wear and prominent wheel-rail noise in curved segments are widespread, which increases the operation and maintenance (O&M) workload and impairs passenger ride comfort. Rail cant is a key parameter that dominates the contact condition between the wheel tread and rail. In this paper, field-validated rail wear model and wheel-rail noise simulation model are established to calculate the rail wear rate and wheel-rail noise level under 9 groups of working conditions with symmetric and asymmetric rail cant combinations. On this basis, the influence characteristics of asymmetric rail cant on the above two indicators are quantitatively analyzed, and the optimal rail cant combination scheme is determined through demonstration, so as to realize the synergistic mitigation of the two core indicators of rail wear and wheel-rail noise.
Research conclusions：(1) A 3D transient wheel-rail rolling vibration model, an Archard wear model, and a noise simulation model based on acoustic boundary element method (BEM) are established, all of which are validated by field measurement data. Simulation analysis is performed on 9 groups of designed working conditions with different rail cant combinations of inner and outer rails, under the boundary conditions of 400 m curve radius, 55 km/h train running speed, and 90 mm track superelevation. (2) The asymmetric rail cant scheme with 1∶40 cant for the inner rail and 1∶20 cant for the outer rail is identified as the optimal solution among all working conditions. Compared with the industry-standard 1∶40 symmetric rail cant, this scheme reduces the wear rate of the inner and outer rails by 7.8% and 11.9% respectively, and decreases the radiated noise from the rail and wheel by 5.2 dB and 4.9 dB respectively. (3) The scheme with 1∶20 cant for the inner rail and 1∶40 cant for the outer rail is the worst-performing solution among all working conditions, which causes significant aggravation of both rail wear and wheel-rail noise. (4) This paper demonstrates that a rational asymmetric rail cant can achieve the synergistic suppression of rail wear and wheel-rail noise. The research results can provide a technical reference for the control of typical track defects including rail wear and wheel-rail noise in curved sections of metro lines in China.

Research purposes: It is of great significance to effectively reduce the economic indicators of municipal railways for controlling project construction costs, accelerating project approval and construction, easing the fiscal pressure on local governments, preventing debt risks, and achieving the sound and sustainable development of municipal railways. Engineering costs account for approximately 63% of the total investment in municipal railways, among which station engineering costs make up around 37%. Stations are one of the key areas for investment control, and lightweight station design serves as a critical technical measure to cut station‑related investment. This paper carries out research from multiple aspects, including station width optimization, buried depth control, equipment room intensification, and simplified decoration standards, and proposes multiple lightweight technical schemes.
Research conclusions：(1) Platform Width Optimization: Island platform width is reduced by 18.18% (from 11 m to 9 m), and side platform width is slightly decreased by 6.7% (from 7.5 m to 7.0 m). (2) Buried Depth Control: Through track ventilation duct adjustment and clearance optimization, the cross-sectional height of underground stations is compressed by 0.8 m. (3) Equipment Room Intensification: Integration of equipment room layouts is made to improve spatial utilization efficiency. (4) Simplified Decoration: An exposed structural finishes scheme is adopted (a "bare installation" approach), reducing decoration investment in public areas by 3.309 million RMB per station (a 34.7% decrease). (5) This study provides references and insights for lightweight design of subsequent suburban railway stations.

Research purposes: The international application of China railway technical standards faces fierce competition from developed countries. Due to differences in national conditions, it is not suitable to fully adopt Chinese standards. Researching the adaptability of China HSR technology to foreign countries, this paper analyzes the influencing factors to clarify adaptive modifications, and proposes a reference for the international application of Chinese technical standards.
Research conclusions： (1) To align with the international forefront of HSR technology, reserve technical capabilities, and accumulate experience, while better meeting the time requirements of passengers, it is recommended that the maximum design speed of HSR be set at 350 km/h. (2) Compared to the open-line sections, aerodynamic loads—including wind pressure—are more significant within tunnels. For 350 km/h high-speed railways, the tunnel cross-sectional area can be optimized from 100 m² to 92 m², and the line spacing can be optimized from 5.0 m to 4.8 m. In station yards, the spacing between tracks should be determined considering the layout of turnouts and facilities between tracks, and should not be less than 5.0 m. (3) Referring to China's intercity railway standards, the length of circular curves and straight between transition curves can be optimized to 0.6 v for general conditions and 0.4 v for difficult conditions. (4) This study recommends a 30‰ maximum design gradient for foreign HSR projects, technical and economic comparisons should be made based on terrain conditions. The length requirements for transition curves are stricter than foreign standards, and it is recommended to refer to China's intercity regulations, using 28 mm/s for general conditions and 35 mm/s for difficult conditions. (5) CRTS Ⅲ slab ballastless track can be adopted for HSR with a speed of over 250 km/h abroad, and ballasted track for weak or special geological conditions. (6) The research can provide a reference for deepening and improving basic theoretical research on China's HSR and for the internationalization of its technical standards.

Research purposes: Jiangsu's high-speed railway features large-scale development, economic prosperity, stringent construction standards, and a focus on meticulous quality control. Optimization should be tailored to its regional characteristics and topographical-geological conditions, with corresponding technical standards clearly defined.This article conducts a research and analysis of the main design standards of Jiangsu high-speed railway and provides corresponding optimization suggestions, which have strong reference value and guiding significance for the design of similar projects.
Research conclusions： (1) Railway passenger stations should be located in the central urban area or near urban developed areas whenever possible. New railway lines should prioritize connecting to existing stations, with no more than one station per county-level administrative division in principle. (2) The phase separation settings should meet operational requirements such as full surveillance, partial surveillance, guidance, visual driving, isolation mode, and starting before the block signal in the forward direction, while the reverse direction should meet the operational needs of full surveillance and partial surveillance in normal mode. Additionally, the onboard automatic control for phase separation must also satisfy the requirement for continuous automatic phase separation. (3) The minimum vertical curve radius for speed-limited sections is optimized from the originally specified 15 000 m, 10 000 m, and 5 000 m for design speeds of 160 km/h, 120 km/h, and 80 km/h to 8 000 m, 5 000 m, and 3 000 m under difficult conditions, respectively. (4) Bridge design should consider the impact of economic height, and optimize the allowable bearing capacity of single pile, the maximum single pile length, and the pile foundation layout of simply supported beam pier in conjunction with regional characteristics. (5) The analysis of Jiangsu's high-speed railway design standards is of great significance for guiding the design of similar high-speed railways around the world.