Research purposes: The Chongqing to Guiyang corridor is the backbone section of the Baotou-Haikou and Lanzhou-Guangzhou high-speed rail corridors, as well as the railway corridor of New International Land-sea Trade Corridor in western China. Currently, it consists of the Chuanqian Line and the Yugui Line, facing issues such as capacity constraints and low transportation quality. Therefore, it is necessary to conduct a systematic study on diversion and alternative construction schemes.
Research conclusions: (1) Combining road network planning and project positioning, this paper predicts the annual traffic volume of the corridor, and analyzes that the diversion schemes for passenger and freight transportation face problems such as insufficient transportation capacity on related routes, long detour distances, and low transportation quality, making them all infeasible. Therefore, new railway lines need to be constructed. (2) The construction schemes propose three options: adding a second line to Chuanqian, maintaining the status quo for Yugui and building a new passenger and freight line, maintaining the status quo for Chuanqian and Yugui while constructing a new high-speed railway, and maintaining the status quo for Chuanqian and Yugui while building a new high-speed railway. The final recommendation is to construct a new high-speed railway that meets planning policy requirements, transportation quality, and economic benefits. (3) The research ideas and methods can provide reference and inspiration for similar projects.

Research purposes: The Wuhan-Yichang section of the Shanghai-Chongqing-Chengdu Railway, as a key section of China's "Eight Verticals and Eight Horizontals" high-speed railway network, is an important intercity channel between the Wuhan urban agglomeration and the Yichang-Jingzhou-Jingmen urban agglomeration. Through the research, it is planned to achieve the scientific introduction of the Shanghai-Chongqing-Chengdu Railway into the Jingmen region and rationally determine the route alignment and station layout scheme of the introduction of the Shanghai-Chongqing-Chengdu Railway into the Jingmen region.
Research conclusions: (1) Based on the current situation of railways in Jingmen area, coordinated urban planning and the direction of Shanghai-Chongqing-Chengdu Railway and Xiangyang-Jingmen-Jingzhou Railway, combined with the pre measurement of passenger train pairs in Jingmen area, five schemes for introducing railway routes into Jingmen area are proposed. (2) By analyzing the route direction and length, engineering investment, station location, transportation organization, adaptability to urban planning, difficulty of project implementation, and social impact, a reasonable layout of the route plan is selected. (3) The introduction plan to the north of the city has the advantages of a straight route, good station conditions, flexible operation, low investment, and easy implementation. It also helps to enhance the radiation and driving ability of Jingmen to surrounding cities. Therefore, it is recommended. (4) The research results can provide reference and guidance for the planning and site selection of similar new railway hubs.

Research purposes: This paper uses the analytic hierarchy process (AHP) to study the evaluation and selection of railway hub schemes for newly built lines. By introducing concepts such as weight, membership degree, and consistency, based on fuzzy mathematical concepts, the relative superiority degree of each scheme is determined under evaluation criteria such as overall layout, transport indicators,technical indicators, and operational indicators. With the goal of maximizing the total relative superiority degree of each scheme, a hierarchical structure model is constructed. The scores of each scheme are quantitatively calculated using Matlab programming, and the optimal scheme is determined through comprehensive scores.
Research conclusions: (1) By introducing the concept of systems engineering and transforming qualitative analysis methods into quantitative calculations for comprehensive comparison of all factors, the traditional list evaluation method can effectively overcome the disadvantage of being greatly influenced by subjective factors.(2) Taking the introduction of Nantong-Suzhou-Jiaxing-Ningbo high speed railway into Jiaxing railway hub as an example, the AHP analytic hierarchy process was used to analyze and verify various schemes, and the results were consistent with traditional evaluation schemes, indicating that this evaluation method has good applicability.(3) The research results have reference value for decision-making on the introduction of railway hub schemes for future planning of new lines.

Research purposes: To study the prestress loss of the anchor cables for super deep foundation pits in soft rock formations and propose corresponding tensioning plans, based on the deep foundation pit project of Huanghua Airport underground station on the Changsha-Ganzhou high-speed railway, comparative experimental research on traditional monitoring of anchor cable axial force and distributed grating fiber optic monitoring was carried out, a numerical model was established for the entire process of anchor cable tensioning in deep foundation pits in soft rock formations, and the prestress loss during the tensioning process of each anchor cable and the deformations of the side wall of the foundation pit were analyzed.
Research conclusions: (1) The prestress losses of the anchor cables in deep foundation pits in soft rock formations are relatively serious, and the prestress losses of some anchor cables can reach over 30%. (2) The prestress losses in the anchor cable are mainly due to anchoring which mainly occurs within 120 minutes after anchoring, and the greater the initial tensioning force of the anchor cable, the more prestress losses after anchoring. (3) For the prestressed anchor cables of the super deep foundation pits in soft rock formations, a step-by-step over tensioning scheme can more effectively decrease the prestress losses caused by the anchoring and tensioning process of the anchor cables, reduce the side wall deformations of the foundation pit, reduce the impact of excavation on the surrounding environment, and then guide the construction of prestressed anchor cables effectively.

Research purposes: There are some issues in the traditional reinforced soil retaining walls, such as the uncontrollable deformation, causing that the application is more cautious in the domestic railway industry. To solve this issue, Japan has developed the rigid face reinforced soil retaining wall, which has been applied over 206 km in railway industry without damage or excessive deformation, even withstanding major earthquakes. Therefore, exploring the differences between the design methods of reinforced soil retaining walls in China and Japan is valuable for improving China's reinforced soil retaining wall design system.
Research conclusions: (1) There are significant discrepancies between Chinese and Japanese standards in all five aspects, such as the backfill design parameter, reinforcement, fracture surface and earth pressure calculation, stability check and reinforcement structure, which will lead to variations in the design of the reinforcement dimensions for reinforced soil retaining wall. (2) Without considering structural requirements, the reinforcement dimensions specified by the Chinese standard tend to be smaller, making the structure more prone to risk compared to the Japanese standard. However, when structural requirements are considered, the reinforcement dimensions in the Chinese standard are generally larger and the structure is safer. (3) The research results can provide some guidance for domestic designers to comprehensively understand the differences between Chinese and Japanese design methods for reinforced soil retaining walls.

Research purposes: This paper established a three-dimensional numerical analysis model of 'bedrock-cover layer-subgrade' that can consider the features of fault creep activity, analyzed the deformation characteristics of subgrade structure under the action of fault creep dislocation, and clarified the action mode and sensitivity of various chief influencing factors on subgrade deformation, such as fault movement mode, creep amount, thickness of overlying soil.
Research conclusions: (1) Different creeping modes of active faults lead to different deformation characteristics of subgrade surface and slope, in particular, the near-fault slope under the action of strike-slip shows obvious 'middle bulging'. (2) Under the action of dip-slip fault dislocation there is a critical creep amount and critical overburden thickness that make the subgrade irregularity range tend to be stable. (3) The increase of strike-slip displacement obviously aggravates the lateral displacement of the subgrade and the 'middle bulging' of a near-fault slope, while the sufficient thickness of overburden will obviously smooth the above lateral deformation. (4) Those analysis results can provide a reference for the deformation control of railway subgrade under the background of fault dislocation.

Research purposes: The use of ballastless track is the development trend of heavy-haul railway, and the structural design parameters are the key to carry out the design of ballastless track on the bridge of heavy-haul railway. The system coupled dynamic analysis model of vehicle-track-bridge was established in this paper, and the influence of rail type, track slab width and track slab thickness on the system dynamic characteristics were analyzed. The comprehensive evaluation was evaluated by analytic hierarchy method, and the design parameters of the single layer long sleeper embedded ballastless track were proposed.
Research conclusions: (1) Compared with 60 kg/m rail, the vertical vibration acceleration of vehicle and wheel-rail vertical force increase when 75 kg/m rail is used, and the displacement and force of track structure decrease. (2) With the increase of track slab width and thickness, the track structure vertical displacement increase, and the vibration acceleration of vehicle, wheel-rail vertical force, rate of wheel load reduction, vibration acceleration of bridge, fastener system reaction force and the contact stress between track slab and bridge decrease. (3) The dynamic comprehensive evaluation results of ballastless track decrease with the increase of the width and thickness of track slab. (4) Combined with the dynamic responses and engineering investment, it is suggested that the rail type is 60 kg/m rail, track slab width is 3.0 m and track slab thickness is 0.275 m used for the single layer long sleeper embedded ballastless track on the bridge of heavy-haul railway. (5) The research results can provide reference for structural design parameter values of single layer long sleeper embedded ballastless track on the bridge.

Research purposes: The Zhongxiang Hanjiang Bridge is a key controlling project of the newly constructed Shanghai-Chongqing-Chengdu High-speed Railway section from Wuhan to Yichang, designed as a (60+78+270+78+60)m double-tower, double-plane cable-stayed bridge to meet navigation and flood control requirements. It represents the largest span concrete deck cable-stayed bridge for high-speed railways with a speed of 350 km/h on a ballastless track in China. This paper conducts an in-depth study on the design of long-span prestressed concrete cable-stayed bridges based on the structural characteristics of this bridge, providing references for similar projects in the future.
Research conclusions: (1) The main girder adopts a prestressed concrete cross-section. Through comprehensive research on aspects such as the bridge's final state after construction, girder height, and tower height, a reasonable structural design scheme has been selected. The post-construction creep of the main girder is controlled to 22.5 mm, and the ballastless track exhibits good compatibility with the bridge. (2) The Zhongxiang Hanjiang Bridge demonstrates excellent static and dynamic characteristics, with favorable load-bearing performance and high safety reliability. (3) Using the 60 m chord midpoint chord measurement method, the calculated design value for static long-wave irregularities of the track is 4.9 mm, meeting the track acceptance standards. (4) An integrated bridge-rail health monitoring system is installed to promptly understand the response characteristics and operational status of the bridge and track structure under various loading conditions. (5) The successful implementation of this bridge marks a breakthrough in the application of large-span prestressed concrete girders on ballastless track bridges designed for speeds of 350 km/h.

Research purposes: With the rapid development of highway and railway in our country, more and more prestressed concrete T-frame bridges are used to cross over existing railways, and the span is getting longer and longer. However, there are relatively few studies on applying the lifting force at the beam end to increase the crossing capacity of prestressed concrete T-frame bridges. In this paper, a 2×116 m prestressed concrete T-frame bridge spanning a railway on a highway with the largest span in China is taken as the research object, by establishing a finite element model, the influence of the lift at the end of the beam on the height of the main beam and the thickness of the web of the long-span prestressed concrete T-frame bridge is analyzed, and then the influence rule and value principle of the lift at the end of the beam on the stress of the main beam are explored.
Research conclusions: (1) The design value of negative bending moment and shear force at the root section of the main beam can be effectively reduced by applying the lifting force at the end of the beam of the long-span prestressed concrete T-frame bridge. (2) Applying the top lift force at the end of the beam can reduce the design thickness of the web of the main beam, and the height span ratio of the fulcrum beam in the main beam can be 1/10, and the height span ratio of the side fulcrum beam can be 1/25, so that the main beam has good technical and economic indicators. (3) The bridge adopts the method of applying the lifting force at the end of the beam after the completion of the bridge, and all the indicators meet the requirements of the code and the design parameters are reasonable, which can be used as a reference for this kind of long-span prestressed concrete T-frame bridge in the future.

Research purposes: To ensure the safety of the construction and operation period of the tunnel in tuff strata, on-site sampling was employed for in-door testing to study the engineering characteristics of tuff strata. Combined with the disaster situation during the construction period of the tuff section in the Liren tunnel of the ongoing construction of the Xi’ning-Chengdu Railway, engineering countermeasures were proposed and their effects were verified on site. It is beneficial to clarify the impact of tuff strata on tunnels and improve tunnel design theory.
Research conclusions: (1) Weakly weathered hard tuff has a tuffaceous sand-like structure, with a mineral composition mainly composed of sand-like minerals. It has relatively good water stability and is mainly non-expansive, so no strengthening measures are needed. Strongly weathered soft tuff has a tuffaceous structure, with volcanic ash as the main mineral composition and a high content of hydrophilic minerals such as montmorillonite. It has obvious water physical properties and is mainly characterized by moderate to strong expansibility. (2) Weakly weathered hard tuff has high strength, good self-stability of tunnel face, and no corresponding section disasters on site. Strongly weathered soft tuff has relatively low strength, and it cannot even be sampled. It is an extremely soft rock, and the self-stability of the tunnel face is poor. There have been multiple instances of face collapse, initial support intrusion, sprayed concrete cracking, and detachment in corresponding sections on site. After excavation, the foundation 1~2 m of tuff collapsed and softened, and measures need to be strengthened. (3) The engineering analogy method is used to propose countermeasures for tunnel engineering in strongly weathered soft tuff. Deformation control measures include strengthening advanced support measures, arch wall radial grouting, setting buffer layers between initial support and secondary lining, etc. The safety control measures for the foundation use steel pipe piles and waterproof layers. Field tests have shown that the above engineering measures have significant control effects. (4) The results of this study can provide a reference for the design of railway tunnels in similar tuff strata.

Research purposes: The excavation face and tunnel top of shield tunnels have completely different failure modes during excavation in clay and sand layers. Based on the assumption of a non-vertical sliding surface, taking into account factors such as incomplete soil arching effect and principal stress deflection, this paper proposes calculation formulas for vertical soil pressure and vertical support soil pressure of circular shield tunnels in clay layers. The rationality of the theoretical model is verified through numerical examples, and sensitivity analysis is conducted on the parameters.
Research conclusions: (1) When the burial depth is shallow, the soil pressure curve approaches linear variation. (2) When the burial depth is deep, the soil arching effect causes the curve to exhibit nonlinear changes, and the soil pressure first increases and then decreases. (3) The vertical soil pressure at the top of the tunnel increases with the increase of internal friction angle, and decreases with the increase of principal stress deflection angle, sliding surface angle, and cohesive force. (4) The sensitivity relationship of each parameter is: cohesion > principal stress deflection angle > soil sliding surface angle > internal friction angle. (5) This research achievement can provide reference and guidance for improving the theoretical system of shield tunnel design and calculation.

Research purposes: At present, the maglev railway is developing rapidly, but the independent tunnel fire rescue under the urban maglev express system is still blank in China. There is a lack of relevant research on the fire rescue mode of the tunnel section of the urban maglev express line project under construction, and the original wheel-rail theoretical achievements are difficult to meet the fire rescue needs of the tunnel section under the maglev system, and it is urgent to carry out the research on the fire rescue mode of the independent tunnel of the municipal maglev express line. In this paper, taking the urban maglev express railway as the engineering background, theoretical analysis and numerical simulation methods are used to study the fire rescue mode of the independent tunnel, and the reasonable rescue mode and safeguard measures for the independent tunnel fire rescue of the urban maglev express railway are obtained.
Research conclusions: (1) Combining the design speed of the project with the characteristics of rapid maglev vehicles, and referring to the situations of urban railways under construction or already in operation, it is analyzed that when a fire occurs on the train, the evacuation rescue method of fixed-point evacuation is adopted in independent tunnels. (2) Different safeguard measures such as external power supply, relay protection, DC system, power supply mode, traction power, and evacuation conditions all affect the reliability of evacuation rescue in independent tunnels. (3) Compared to wheel-rail systems, rapid maglev trains have stronger reliability. Even in the most unfavorable situation of power loss, the train can still use the battery to suspend and use inertia to glide for a longer distance, allowing flexible control of the train to ensure smooth driving out of the tunnel. (4) The research results can provide reference for the engineering design of the tunnel section of the maglev express line under construction.

Research purposes: In response to the requirement of signal system switching between the CTCS signal system and the CBTC signal system for the cross-line operation of trains in suburban railways, the technical routes of different signal system switching are analyzed and studied in terms of the advancement of technical routes, conformity of specifications and so on, the switching locations of different signal system switching are compared and analyzed in terms of safety of switching locations, division of dispatching boundaries for different type of railways and so on, and the applicability of each technical scheme of different signal system switching for cross-line operation to the construction of different projects is systematically clarified.
Research conclusions: (1) The technical route that the systematic structure and communication interface of the CTCS signal system and CBTC signal system are completely independent and should be adopted in the project that will be constructed soon, such as the project of running suburban trains in the Beijing Railway Hub Northeast Ring Railway. (2) The technical route that the CTCS signal system is independent, and the CBTC signal system adds new conversion equipment using the existing communication interface of the CTCS signal system and CBTC signal system, and the technical route that systematic structure of the CTCS signal system and CBTC signal system remains unchanged and system equipment of CTCS signal system and CBTC signal system increases the communication interface can be applied in construction projects after completing the preconditions of project implementation such as certification and licensing and so on. (3) The technical route of systematic structure and communication interface of the CTCS signal system and CBTC signal system are completely integrated is the development direction of the signal system, which can be applied in long-term projects. (4) The stopping at junction stations of different types of railways should be selected to complete the different signal system switching for cross-line operation in the project. (5) The research results proposed in this paper can provide a reference for the design and construction of other suburban railway projects.

Research purposes: China has maturely applied and formed a technical system for overhead contact systems and equipment at 350 km/h and below, but still lacks relevant technical standards and engineering applications at operating speeds of 400 km/h. It is urgent to study the feasibility of the existing overhead contact system at a higher operating speed of 400 km/h to promote the implementation of the CR450 scientific and technological innovation project. This paper combined with the existing typical overhead contact system types in China, through the dynamic coupling simulation of the bow and catenary and the analysis of high-speed comprehensive test data, the tension, facility section, and equipment of the existing overhead contact system were studied to be more adaptable at a higher operating speed of 400 km/h. It is proposed that the existing overhead contact system cannot meet the operating requirements of a higher speed of 400 km/h, and the next research ideas and directions are proposed.
Research conclusions: (1) The existing overhead contact system has deteriorated the current-collecting quality of the catenary at a speed of 400 km/h. When the EMU is running with a single pantograph, it is close to the standard limit. When the EMU is running with double pantographs, it cannot adapt the requirements of higher speeds. (2) When the existing overhead line system runs at a speed of 400 km/h, the spatial dynamic displacement of the conductors, positioning, droppers, elastic suspension cables, electrical connections, etc. increases, and the conductors and components are prone to collision and wear, increasing safety risks. (3) The existing overhead contact system has aggravated equipment vibration fatigue when operating at a speed of 400 km/h. Although it can meet the load strength requirements, the durability and stability of the system and equipment are reduced, and the service life is greatly shortened. (4) The research results can provide a reference for the construction operation and maintenance of high-speed railway projects in the field of rail transportation.

Research purposes: The photovoltaic industry is of great significance for the realization of the dual-carbon goal, and the railway department has also introduced corresponding policy documents to support the development of the railway photovoltaic industry. However, the instability of its output has a great impact on the power supply and distribution network and seriously affects the stability of the power grid. The railway load is small but with the high importance, the unstable output of PV system limits the application of PV system in railway power supply system. Therefore, building water system and PV system is integrated to form a kind of self anti-interference control circulatory system among solar, hydroenergy and electricity, to provide stable and controllable electric energy, in the paper.
Research conclusions: (1) The self anti-interference control circulatory system can realize the energy recycling among solar, hydroenergy and electricity. (2) The active power controllable, good waveform of high-quality electric energy, can be used as a constant power source to provide stable electric energy to users. (3) The adaptive loads fluctuation can realize power flow-up control of microgrid output and load fluctuation. (4) The higher utilization rate of PV system can reduce the impact of PV system on the railway electric power supply system. (5) The system can be widely used in fields such as railway electric power supply system, civil building, municipal, etc.

Research purposes: The quality inspection of railway tunnel linings is crucial for tunnel integrity and railway operational safety. Currently, the detection of tunnel lining defects primarily relies on the manual interpretation of radar images, and the process is inefficient and subject to significant subjective bias. To enhance the efficiency of defect detection, this study proposes an intelligent detection technology based on convolutional neural networks for tunnel lining defect images. Furthermore, to improve the applicability of this technology in practical engineering, we focus on developing a more lightweight tunnel lining defect detection technique.
Research conclusions: (1) Analysis of radar images of tunnel lining defects revealed significant background interference and a high dependence on prior knowledge of defects, resulting in low identification efficiency. (2) A novel method for determining insufficient lining thickness was developed. This method can filter most background noise and effectively mark thickness deficiencies. (3) A new lightweight network model for detecting tunnel lining defects was constructed. Comparative experiments demonstrated that the model accurately detects voids and rebar deficiencies, achieving high detection precision with excellent lightweight performance. (4) Field trials demonstrated the practical engineering applicability of this technology in railway tunnel quality inspections, providing an effective alternative to manual identification methods for detecting tunnel lining defects.

Research purposes: Based on the hazards of shield residues by traditional disposal methods, this paper takes Chongqing shield residues as the research object to identify the physical and mechanical properties and microstructure of shield residues in sand and mudstone strata through indoor experiments. Then, the advantages of resource utilization of shield residues will be made clear, and resource utilization ideas will be systematically put forward.
Research conclusions: (1) The shield residues, mainly composed of moderately weathered sandstone and mudstone formations, belong to low liquid limit clay with good gradation and continuous soil particle size. It is mainly composed of minerals such as quartz, corundum, calcite, and sodium feldspar, and is weakly alkaline. (2) In sand and mudstone formations, shield residue has the advantages of uniform particle size and continuous gradation, high hardness of mineral particles, stable behavior, and weak alkalinity. And the mechanical properties and durability of recycled products can be effectively guaranteed. (3) From the view of the resource utilization of shield residue, it should be considered that the proportion of polymer in the residue improver should be increased appropriately. The particle size grade of residue can be increased, and the wear of the cutter head and cutter tool during shield tunneling can be reduced correspondingly. To ensure the stability of the foundation after backfilling, the moisture content of shield residue should be maintained at around 42%. (4) A general idea of solidification utilization and fluid utilization is proposed through hierarchical classification processing. The preliminary theoretical system for recycling shield residues is constructed. And the advantage of carbon emission reduction is made clear. (5) This paper can provide reference for the resource utilization of similar residues in the future.

Research purposes: The trackside equipment is very important to the operation safety. Due to the high departure density of urban railways, the trackside equipment in the tunnel is subjected to reciprocating aerodynamic load, which makes it easy to loosen the mounting bolts of railside equipment, and then causes serious safety accidents. In this paper, the aerodynamic load of trackside equipment in an urban railway tunnel is studied by using the CFD dynamic grid numerical calculation method, and the influence of installation position on the aerodynamic load is analyzed.
Research conclusions: (1) The extreme position of the pressure measurement point in the tunnel is not consistent with the extreme position of the aerodynamic load on the trackside equipment. (2) The aerodynamic load on the power box is mainly caused by the train wind when the train passes through. However, the influence of compression waves and expansion waves in the tunnel is superimposed during the train's passing at different locations, resulting in different aerodynamic loads on the power box at different locations. (3) The aerodynamic force of the equipment on the evacuation platform side is greater than that on the other side of the track. The equipment installed at the bottom of the tunnel section receives more aerodynamic load than that in the middle of the tunnel. (4) The trackside equipment should be installed on the opposite side of the evacuation platform and as high as possible.

Research purposes: The human resource management system based on the competency model focuses more on individual competence compared to work activities, which facilitates better selection and cultivation of excellent employees for enterprises. This is particularly important for enterprises that are flexible and adaptable in the rapidly changing information society. This paper takes Z Group as an example to study the construction and implementation of a human resource management system based on the competency model.
Research conclusions: (1) Talent selection emphasizes high standards, not only focusing on the relevant knowledge and skills of the position, but also on the development of core competencies. (2) Establish a talent growth and learning map, strive to improve the overall quality and innovation ability of the talent team, and achieve mutual benefit between the enterprise and employees. (3) Innovate the performance evaluation management system, improve the mechanism for determining total salary, and stimulate the enthusiasm of various talents for entrepreneurship. (4) Based on the needs, adhere to targeted talent introduction, innovate talent introduction methods, and continuously improve the matching degree between the talent team and the development of the enterprise. (5) This research result can provide a method and path for large railway construction enterprises to explore the establishment of a sound and effective human resource management system, and continuously improve their core competitiveness.