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Copyright of Journal of Shenzhen University Science & Engineering is the property of Editorial Department of Journal of Shenzhen University Science & Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Shenzhen University Science & Engineering is the property of Editorial Department of Journal of Shenzhen University Science & Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of New Architecture is the property of New Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

［Objective］As in China E-CNY (hereinafter referred to as "digital currency") flourishes in all walks of life, the application scenarios of digital currency in urban rail transit are gradually enriched. Traditionally, digital currency is only used as a third-party payment application in rail transit, with functions similar to those of Alipay and WeChat. In order to further expand the application scenarios, it is proposed to use the digital currency APP (application software) to directly generate the digital currency boarding code, so that passengers can directly use the digital currency QR code to enter and exit the stations, making the digital currency travel scenarios more convenient. ［Method］The overall architecture and each module functions of the digital currency payment system in urban rail transit application scenarios are introduced; the digital currency QR code design schemes and key business processes are introduced. ［Result & Conclusion］Using digital currency soft wallet, and based on two asymmetric keys, the digital currency key and the subway key, the digital currency QR code is generated with reference to the Ministry of Transport QR code encoding format at the same time. With the digital currency key and the subway key as security guarantees, key business processes such as APP code request, gate code verification, and payment settlement are clarified.

［Objective］Due to their low tensile strength and poor impact resistance, ordinary concrete segments are prone to problems such as cracking and deformation during the transportation and construction process. Adding fibers is an effective way to prevent and control these defects. Therefore, it is necessary to study the effects of different fiber materials on the performance of concrete segment joints. ［Method］Through indoor tests, concrete segments containing steel fibers, polypropylene fibers and two types of mixed fibers are designed, and compared with ordinary concrete segments without admixtures, so as to analyze the effects of different types and dosages of admixtures on compression, bending and pull-out properties at concrete segment joints. On the basis of determining the optimal admixture materials, the effects of different admixture dosages on the mechanical properties of concrete segment joints are studied. ［Result & Conclusion］The addition of fibers can effectively prevent the crack development at concrete segment joints, among which the concrete with mixed fibers has the most obvious improvement on the overall performance of the concrete segment joints. The greater the fiber dosage, the more effective it is in preventing crack development at the joints. From the perspective of the crack development characteristics of the segments, with the addition of fibers, almost no visible development of penetrating cracks. The greater the fiber dosage, the more obvious this improvement is in crack development .

［Objective］Aiming at the difficulties of detecting small-volume parts of rail transit catenary under few-sample conditions, a defect detection method integrating generative adversarial networks and deep segmentation models is proposed. ［Method］The composition of the detection system, the improved DCGAN (deep convolutional generative adversarial network) structure and the improved YOLACT (single-stage conditional adversarial network) model are introduced, and the defect detection effect is verified based on the actual defect datasets. ［Result & Conclusion］In the sample expansion part, the improved DCGAN model can improve the quality of generated samples by introducing several normalization operations and adding an efficient channel attention mechanism. In the model detection part, the improved ResNeXt-FPN (deep con-volutional neural network combining residual network and feature pyramid network) structure is used to replace the backbone network of the original YOLACT model, aiming to fully characterize the multi-scale features of the target. The introduction of CS (channel and space) attention mechanism in the mask branch network can effectively improve the detection accuracy of small-volume parts. The proposed defect detection model can achieve high-precision detection of cotter pins in complex contact network images, with a detection accuracy and recall rate of up to 88.63% and 87.49% respectively. Compared with the original YOLACT model, the comprehensive performance of the proposed defect detection model is improved by about 6.2%.

［Objective］During shield tunneling in water-rich soft strata, ground deformation is often influenced by the combined effects of soil strength, deformation, and permeability characteristics. The time effect caused by permeability characteristics may further impact the surrounding environment. Therefore, it is necessary to use a reasonable constitutive model to conduct stress-seepage coupling calculations, and study the ground deformation response induced by shield tunneling in saturated silty clay. ［Method］Taking the Yuchijing Station-Baihetan Station interval on Suzhou Rail Transit Line 11 as an example, a subloading Cam-Clay model that reflects the state correlation of soil mechanical properties is adopted, and combined with a stress-seepage coupling finite element program, to calculate and analyze the land subsidence and pore water pressure response patterns induced by shield tunneling in saturated silty clay. The results are compared with the field-measured engineering data. ［Result & Conclusion］The stress-seepage coupling calculation based on the subloading Cam-Clay model can effectively reproduce the effects of shield tunneling. Shield tunneling in saturated silty clay can easily induce ground deformation, which is significantly affected by changes in the excavation face pressure. The excessive excavation face pressure often induces ground heave. Shield construction causes extrusion disturbance to the soil in front of the excavation face, which in turn induces the evolution of excess pore water pressure in the surrounding soil layers. This is also the intrinsic mechanism for the time effect of ground deformation.

［Objective］The construction of new shield tunnels under-passing existing railway can cause deformation of the former railway subgrade. To ensure the stability and safety of the existing railway, appropriate reinforcement measures must be adopted. ［Method］The Shanghai Airport Connection Line under-passing Lijiatang-Shenzhuang Railway project is analyzed as a study case, which adopts a reinforcement scheme involving ′portal isolation piles+ground grouting′. Numerical simulation results and on-site monitoring data are used to assess the impact of shield tunnel under-passing construction on the existing railway, and to evaluate the effectiveness of the ′portal isolation piles+ground grouting′ reinforcement scheme. ［Result & Conclusion］The shield tunnel under-passing construction may cause significant settlement of the existing railway subgrade, while the ′portal isolation piles+ground grouting′ reinforcement scheme effectively controls the above-mentioned railway subgrade deformation. According to numerical simulation results, the maximum settlement of existing railway subgrade decreases by 67% after reinforcement, and the convergence deformation on tunnel upper part decreases by approximately 41%. All deformations are within the limits specified by the relevant standards. On-site measurements confirm that the cumulative deformation of existing railway track and subgrade caused by the shield construction meets the regulatory requirements. However, due to the impact of shield tunneling, larger deformation fluctuations are observed in existing railway subgrade and track on one side of the shield tunneling.

［Objective］Since the implementation of the Shanghai Master Plan (2017-2035), with the development of five new Shanghai towns (Jiading, Qingpu, Songjiang, Fengxian, and Nanhui) and the Yangtze River Delta integration ascending to national strategies, Shanghai urban rail transit planning network is also undergoing further adjustments. Among them, circle lines and express lines (shorten as circle/express lines) are the focus of discussion, and it is necessary to study the functional planning, passenger flow characteristics and planning principles of circle/express lines. ［Method］Using the passenger flow data of existing urban rail transit lines, the characteristics and functions of circle/express lines passenger flow are analyzed; by comparing the previous research conclusions and actual operation status of circle/express lines, the planning experience of circle/express lines is summarized. Based on the urban development plan requirements in the new era, the shortcomings of circle/express lines in the existing plan are analyzed, and the functional requirements and planning principles of them in the new round of plan adjustments are proposed. ［Result & Conclusion］The passenger flow carried by the circle line is divided into three categories: passenger flow along line service range, transit passenger flow and arrival/departure passenger flow of the line. The corresponding circle line can play service functions for the above three scenarios. In addition to the existing circle line—Shanghai Rail Transit Line 4, the second circle line can be planned to meet the needs of passenger flow distribution along the line. It is recommended that the second circle line can be located between the middle and outer ring roads, making use of the planned Shanghai Rail Transit Line 26, and better closer to the middle ring line. The planning of express lines from suburbs to central urban area should be further strengthened. There are direct access and hub access two forms of express lines entering the central urban area network. Hub access requires highly convenient hub station for this purpose, while direct access to the network features relatively high cost. The corresponding indicator calculation method of express line travel time may be selected based on the connection closeness degree between new towns and the central urban area.

［Objective］When a train running on the viaduct track, the rail vibration caused by the vehicle-track interaction will be transmitted to the bridge, piers, and pile foundations through the track structure, thereby triggering ground vibration around the bridge. Therefore, it is necessary to study the impact of elevated section rail and track bed vibration reduction on the environment for elevated rail transit. ［Method］Based on the vehicle-track multi-body dynamics theory and the finite element method, a vehicle-track-U beam bridge-soil vibration model is established to solve the vibration response of the ground source intensity near the viaduct when rail transit veh-icles passing through. ［Result & Conclusion］The peak frequency band of the ground source intensity vertical vibration frequency for elevated section is distributed in 40 ~ 60 Hz. Vibration-damping fasteners, trapezoidal sleepers, vibration-damping pad floating plates and steel spring floating plates all have a reduction effect on the ground source intensity vibration, and their contribution is mainly reflected in the vibration frequency range of 25 ~ 100 Hz. Under the conditions of using vibration-damping fasteners, trapezoidal sleepers, vibration-damping pad floating plates, and steel spring floating plates, when the vibration frequency is 40 ~ 50 Hz, the ground source intensity vibration acceleration levels are reduced by about 4.2 ~ 4.4 dB, 6.5 ~ 6.9 dB, 7.8 ~ 8.1 dB and 10.0~10.7 dB respectively. When the fastener stiffness is ≤15 kN/mm, the rail vertical displacement and vertical acceleration peak value increase significantly. When the fastener stiffness decreases from 60 kN/mm to 10 kN/mm, the rail vertical displacement and acceleration peak value increase by about 5 times and 18.26% respectively. In the peak frequency band of 40 ~ 50 Hz, the vertical vibration acceleration level at the ground source intensity decreases by about 4.5 ~ 4.9 dB.

［Objective］To enable proactive adjustment of the cooling capacity for metro train AC (air-conditioning) system based on ambient temperature, it is essential to study the prediction of return air temperature in metro train AC systems. ［Method］A time series forecasting method is employed to predict the variation trend in return air temperature of metro train AC systems. Real-time operational data from the air-conditioning system of a Guangzhou Metro train are collected through AC sensors. Outliers are removed using a boxplot, and a sliding window approach is applied to handle the time span of input and output data. An LSTM (long short-term memory) neural network model is then constructed to predict the return air temperature of the AC units, and the impact of different sample sizes on the model prediction accuracy is comparatively analyzed. ［Result & Conclusion］The LSTM neural network model can learn the temperature control logic of metro train AC system, with the predicted temperature curve closely matching the actual temperature curve, therefore is suitable for predicting the return air temperature of metro AC units. Through parameter optimization, the model accuracy is improved to 0.84, enabling precise prediction of unit return air temperature. Increasing the sample size for a single training session can shorten model training time but may reduce the model final prediction accuracy to some extent correspondently.

［Objective］To analyze the relationship between carbody stiffness and modal, and to provide theoretical support for the modal analysis of lightweight carbodies, it is necessary to conduct a theoretical study on both aspects. ［Method］Taking the 25T passenger vehicle as the research object, a finite element model of the carbody is established. Static and dynamic performance analysis of the carbody is carried out to identify key structures affecting the carbody modal. A carbody plate-beam mixed finite element model is established based on carbody geometric features. Using the optimal Latin hypercube sampling method, 40 sets of design variables for the chassis are obtained, and the carbody modal and equivalent stiffness results under different geometric parameters are further calculated. The modal of the lightweight carbody is calculated and analyzed based on the function relationship between carbody stiffness and modal. ［Result & Conclusion］The equivalent bending stiffness and equivalent torsional stiffness of the carbody are linearly and positively correlated with the first-order vertical bending and torsional modal frequencies, respectively. The optimized finite element results of the carbody show that the first-order vertical bending modal frequency increases from 9.04 Hz to 9.24 Hz, and the first-order torsional modal frequency increases from 15.99 Hz to 16.66 Hz, which are consistent with the theoretical relationship between stiffness and modal frequency.

［Objective］To study the land subsidence variation patterns induced by foundation pit dewatering under complex conditions, the deep foundation pit project at Nanjing Metro Line 5 Airport Road Station is taken as a case study to predict the land subsidence caused by foundation pit dewatering. ［Method］Field pumping tests and theoretical analysis are employed to analyze the land subsidence patterns induced by foundation pit dewatering. Single-well and multi-well pumping tests are conducted. The single-well pumping tests provide data on land subsidence patterns and dewatering influence radii for different soil conditions, while the multi-well pumping tests reveal the shapes of dewatering funnels across four typical cross-sections. A land precipitation subsidence prediction formula is derived using the subsidence consolidation equation tailored to the project conditions. The theoretical land subsidence values predicted by this formula are compared with field-monitored data to verify its applicability. ［Result & Conclusion］The influence radius of single-well pumping increases with permeability coefficient and dewatering depth, reaching about 5 meters in low-permeability soil and up to 20 meters in high-permeability soil in this project. The shape of the precipitation funnel follows an exponential curve, and land subsidence deformation is greater adjacent to the dewatering well. Land subsidence induced by dewatering rapidly decreases with distance increasing from the well.

［Objective］To determine the optimal metrics indicators for measuring parking lot congestion and road congestion levels, it is essential to study their impact on the modal share of urban rail transit. ［Method］Eight potential metrics indicators for measuring parking lot congestion are proposed, considering factors such as the number of parking lots, the number of parking spaces, the walking influence range of urban rail transit stations, and travel distance reductions. Additionally, two possible metrics for road congestion are introduced, taking into account road section length and congestion level. Using the inter district transportation data in Kinki metropolitan region of Japan, covering passenger flow, road traffic and parking lots, an empirical analysis is conducted to evaluate the influence of each metric indicator on the variation in urban rail transit modal share. Correlation analysis is then used to determine the optimal metrics. ［Result & Conclusion］Increasing the destination parking lot and road congestion levels leads to a higher all-day urban rail transit modal share between traffic zones. When the O (origin) traffic zone is located in urban or suburban areas, the optimal metric for destination parking lot congestion is advisable to adopt the proportion of highly saturated parking spaces within a traffic zone, adjusted according to distance. When the O-zone is in the central district, the optimal metric indicator for congestion in destination parking lots should adopt the proportion of highly saturated parking lots within the traffic zone, adjusted according to distance reductions. The best metric indicator for road congestion should adopt the total length of congested roads between traffic zones weighted by congestion levels.

［Objective］The transverse joints within the panels of prefabricated diaphragm walls are the weak points in the entire wall structure. Therefore, it is necessary to study the stiffness and strength characteristics of these joints. ［Method］In conjunction with prefabricated diaphragm walls commonly used in foundation pit engineering, a new type of transverse welded joints for prefabricated diaphragm walls is introduced. The force and deformation behavior of this new joint under bending moment actions are studied using numerical simulation methods. ［Result & Conclusion］Under bending moment actions, the tensile stress in the concrete at the end of the angle steel on joint tensile side is the highest, while the compressive stress in the concrete at this position on joint compressive side is the highest. The failure of the joint begins with cracks of the concrete on tensile side. The deflection curve of the component shows no significant mutation at the joint, indicating good deformation performance of the joint, which effectively prevents water leakage. The stress in the angle steel, weld, and rebar on joint tensile side is greater than that on the compressive side. After cracks appear in the concrete on the tensile side, the stress in the angle steel, weld, and rebar of the prefabricated component remains at a low level.

［Objective］With the advantages of diverse functional positioning, flexible line layout, economic and environmental protection, low-carbon, etc., the low-capacity urban rail transit system has become an important part of urban rail transit development. However, due to its characteristics of diverse system modes, diverse application environments, and different development processes, it is necessary to study the problems currently existing in the construction and operation of the low-capacity system. ［Method］A development overview of the low-capacity urban rail transit system is introduced. Combined with relevant national policies, challenges faced by the system in the construction and operation process are analyzed from the aspects of operational efficiency, project cost, investment and financing models, and modes selection. ［Result & Conclusion］Corresponding development suggestions are put forward from the aspects of promoting integrated construction and networked operation to improve operational efficiency, implementing intensive land use and streamlined configuration to reduce project costs, adopting innovative investment and financing to reduce local government debt risks, and conducting post-evaluation or benefit evaluation of operating projects. It is also recommended to select the low-capacity system mode according to local conditions and build an economical and applicable multi-level, multi-mode low-capacity system.

［Objective］Earth chamber pressure is a key parameter for EPB (earth pressure balance) shield construction assessment. Accurate prediction of earth chamber pressure helps construction technicians take timely control measures to ensure subway tunnel construction safety. Therefore, it is necessary to study the earth chamber pressure prediction method of EPB shield. ［Method］A multi-branch LSTM (long and short term memory)-DNN (deep neural network) fusion model is proposed. LSTM branch extracts its time series evolution characteristics by backtracking historical data, while DNN branch extracts excavation state characteristics. The two branches are combined and then integrated through a fully connected layer to realize the prediction of earth chamber pressure. This multi-branch model is verified based on the actual shield tunnel data of Jinan Rail Transit Line 1, and compared with LSTM and DNN models respectively. ［Result & Conclusion］The prediction model of earth chamber pressure based on LSTM-DNN fusion algorithm can converge efficiently, and has good prediction effects on the training set and the verification set. In the subsequent 100-step test, the predicted value of earth chamber pressure obtained by the LSTM-DNN fusion model better reflects the change trend of the actual value, with an average deviation of 7.65 kPa and a relative error of 6.09%, indicating a higher prediction accuracy.

［Objective］To investigate the dynamics issues arising from the frequent lifting and lowering of pantographs in multi-mode hybrid traction trains, the pantograph collision characteristics are analyzed. ［Method］Taking the PC (pantograph-catenary) system as research object, a PC collision test bench is built to study the dynamics characteristics of pantograph collisions during the lifting process. A corresponding dynamics model is established and validated using experimental data. The variation patterns of vertical collision contact forces are also analyzed. ［Result & Conclusion］During PC collisions, collision speed and contact wire stagger value both significantly affect the maximum value, standard deviation, and dynamic coefficient of PC vertical contact force. As the collision speed increases, both the standard deviation and the maximum value of the vertical contact force increase accordingly, while the dynamic coefficient initially decreases and then increases, reaching its minimum when the collision speed is 0.5 m/s. As the stagger value increases, the standard deviation of the vertical collision contact force decreases. At a lower collision speed, the maximum value of the vertical contact force decreases with the increasing collision speed. Conversely, at a higher speed, the minimum vertical contact force initially decreases and then increases, reaching a minimum around a stagger value of 200 mm. Across all speed conditions, the dynamic coefficient is highest when there is no stagger and reaches its lowest point around a stagger value of 400 mm.

［Objective］With the continuous advancement of urban modernization in China, the available space within cities is becoming increasingly scarce. Deep foundation pits are often constructed in environmentally sensitive areas, inevitably making impact on the surrounding environment. This is particularly true for deep foundation pits in areas with thick, water-rich sand layers, where improper construction control can easily lead to severe hazards. Therefore, it is necessary to study the impact of deep foundation pit covered-excavation reverse construction in water-rich sand layers on the surrounding environment. ［Method］Using Shenyang North Railway Station on Shenyang Metro Line 4 as an example, the deformation impact of deep foundation pit construction on the above-ground buildings, underground structures, underground pipelines, and power corridors is analyzed through construction monitoring method. ［Result & Conclusion］In the initial stages of excavation, the above-ground buildings primarily exhibit settlement deformation. As the excavation depth increases, settlement deformation gradually decreases, eventually presenting as upheaval deformation. The deformation of underground structures is significantly affected by the position of the excavation face, with maximum deformation occurring when the excavation face approaches the foundation buried depth of the structures. Underground pipelines show a clear positional impact, with the deformation of the right-side pipelines being much greater than that of the left-side pipelines, both primarily exhibiting settlement deformation. The deformation of power corridors is closely related to foundation pit excavation depth. When the excavation depth is relatively shallow, the power corridors are largely unaffected, but during the excavation of the fourth underground level of the station, the deformation of the power corridors begins to increase gradually.

［Objective］The optimization and adjustment of development scale centered on urban rail transit stations is conducive to promoting the formation of an efficient and intensive urban spatial development model and improving the passenger flow benefit of the urban rail transit system. However, existing studies generally optimize the surrounding development based on a single station. Therefore, it is necessary to study a multi-station land development collaborative optimization model based on passenger flow benefit improvement. ［Method］From the multi-station perspective of urban rail transit lines, a collaborative optimization of multiple stations surrounding development is carried out. On the basis of improving passenger traffic intensity, the passenger flow utilization balance in each section is optimized, the number of permanent population and employment opportunities is used to characterize the development scale. Based on the line passenger traffic intensity, the station entry coefficient at peak hours and the maximum one-way section imbalance coefficient at peak hours, a comprehensive passenger flow index is constructed, and used as the objective function to establish an optimization model. Particle swarm algorithm is used to solve the function under a series of constraints to achieve collaborative optimization of urban rail transit passenger flow and development scale. Taking six stations on the east extension section of Guangzhou Metro Line 5 as the optimization objects, the effectiveness of the optimization model and solution algorithm are verified. ［Result & Conclusion］The proposed algorithm can complete convergence in less than 100 iterations. Under the specified parameters of the case, the permanent population and employment scale of the eastern extension section can be increased by 55.3% after optimization, and the passenger flow comprehensive indicators be improved by 7.9%. Among which, the passenger transport intensity is improved by 11.1%, and the peak hour entry coefficient and peak one-way maximum cross-section imbalance coefficient are reduced by 3.4% and 4.6% respectively, verifying that the proposed optimization model solution method is fast and effective.

［Objective］Due to the unclear load pattern, the final internal force design value often deviates from the actual value when a tunnel crosses transverse composite strata. Therefore, it is necessary to study the interaction between the metro shield tunnel segments and the soil in composite strata with soft upper layers and hard lower layers. ［Method］Taking the Liuxiandong Station to Baiwang HKU Station shield tunnel crossing the mixed granite interval on Shenzhen Metro Line 13 as an example, the internal force situation of the main structure is analyzed. Based on the field-measured values after the segment internal force stabilizes, parameters for the inversion analysis are selected, and an optimization objective function is defined. The QPSO (quantum particle swarm optimization) algorithm is used to optimize the load parameters, and the reasonable parameter values and specific loading conditions in the upper-soft and lower-hard strata are obtained through inversion analysis. ［Result & Conclusion］Compared with the values in TB 10003-2016 Code for Design of Railway Tunnels, the load parameters obtained through QPSO algorithm inversion calculation are more suitable for the upper-soft and lower-hard strata. The calculated internal force distribution is more similar to the actual situation, verifying the feasibility and rationality of the proposed analysis method. For composite strata with upper-soft and lower-hard layers, the tunnel overburden load can be calculated using the collapse arch height, and the lateral pressure coefficient of the lower hard rock section should be appropriately amplified for geological survey values.

［Objective］During the parallel construction of multi-line tunnels, the excavation of subsequent tunnels will adversely disturb existing tunnels. Compared to double-line tunnels, the disturbance caused by multi-line tunnel parallel construction is more complex, necessitating researches on risk prevention-control strategies and structural safety. ［Method］Using a rail transit interval line and depot station underground excavation tunnel project as example, risk identification, prevention-control and safety analysis are conducted. The structural reliability criteria are used to quantify and determine highly affected areas during three-line tunnel parallel construction. The risk prevention-control measures for existing underground excavation tunnels in these highly affected areas, specifically in-tunnel reinforcement measures are introduced. A three-dimensional refined numerical model is established, the land subsidence and existing tunnel stressed deformation corresponding to different stages of tunnel parallel construction are analyzed, and the structural safety states and reliability of reinforced measures are evaluated. ［Result & Conclusion］Existing underground excavation tunnels with small clearance exhibit significant displacement and deformation during the excavation of the right-line shield tunnel. The disturbance impact caused by the subsequent shield tunnel decreases significantly as the distance from the preceding tunnel increases. The overall reinforcement measures using cross braces and arch canopies can effectively mitigate the additional deformation and stress on existing structures caused by the disturbance of subsequent shield tunnel construction.

［Objective］In recent years, pushed by new urbanization with metropolitan areas and urban clusters as carriers, the planning and construction of Shanghai city railway develop rapidly. In order to better comply with development requirements, suggestions for the planning and construction of city railways are proposed. ［Method］By reviewing the development history of Shanghai city railways construction, current development status and characteristics of Shanghai city railway are summarized in terms of meeting the requirements of new urbanization development, multi-level rail transit integration, and operational service optimization. In comparison with national policy requirements, it is pointed out that there is still room for Shanghai city railway optimization in terms of further strengthening multi-level network integration, utilization of existing national railways, hub anchoring, network planning layout, and line planning implementation. ［Result & Conclusion］The development of Shanghai city railways should adhere to the concept of "integrated development, optimal time, and hub anchoring". In terms of specific line schemes, it is necessary to combine needs, strengthen system functions, optimize railway standards, select key hub anchoring points and external connection points to create integrated demonstration stations, and further improve the level of interconnection; it is necessary to integrate into urban development internally, and strengthen cross-regional connections externally for the further optimization of planning network forms. To achieve higher-quality development goals, it is required to innovate actively in terms of revitalizing national railway resource utilization, integrating operation and management, constructing guarantee system, intelligent operation and maintenance, and breaking through institutional and policy bottlenecks.

［Objective］Rail transit safety hosts are the core of the train operation control system, and it is necessary to conduct safety research on the rail transit safety hosts. ［Method］The system architectures of the 2-out-of-3 safety host and the double 2-vote-2 safety host are introduced. A quantitative calculation method for the safety hosts that combines Markov method and GO method is proposed and verified through actual example. ［Result & Conclusion］Within the same working period, the safety of the power module decreases the fastest. So in practical applications, special attention should be paid to the safety of the power module in the safety hosts. In the initial working period, the security performance of the double 2-vote-2 safety host is higher than that of the 2-out-of-3 safety host, but the difference in security performance between the two safety hosts is not significant; with the increase of working time, the security performance of both safety hosts decreases. Adoption of the proposed Markov-GO joint model can achieve safety quantitative analysis of the safety hosts.

［Objective］In order to ensure the shield tunnel construction safety in water-rich sandy cobble stratum when passing through underground cavities, it is necessary to study the safe distance between the shield tunnels and the underground cavities. ［Method］Taking the tunnel project of Nanchang Metro Line 1 East Extension as an example, combining theoretical calculation and numerical simulation methods, a quantitative analysis is conducted on the safety distance between underground cavities and tunnels based on the catastrophe theory. The above-mentioned safety distance is calculated by combining the structural mechanics approximate analysis method, and a calculation model for the safety distance between the shield tunnels in water-rich sandy cobble stratum and the underground cavities is established. The rationality of the proposed calculation model is verified by the Abaqus software numerical simulation, taking whether the plastic zone of the rock-soil system between the underground cavity and the tunnel is connected as the criterion. ［Result & Conclusion］The proposed calculation model for the safety distance between the shield tunnels in water-rich sandy cobble stratum and the underground cavities has certain accuracy and rationality and can be applied in engineering practice. The above-mentioned safety distance increases as the span of the underlying cavity increases, decreases as its height-to-span ratio increases, and increases as the level of surrounding rock influence factors increases.

［Objective］The tunnel between Shengchanlu Station and Lihuanglu Station on Jinan Metro Line 2 passes in close proximity to the pile foundations of an elevated bridge and the Eurasia Electronics Building complex. To ensure the smooth implementation of shield tunneling and the safety of existing structures, it is necessary to study the structural response mechanism of the surrounding soil and buildings due to shield tunnel side-passing construction. ［Method］Using finite element simulation, the deformation of adjacent bridge foundation, pile foundation, and ground surface before and after reinforcement during the right and left line shield tunnel crossings is examined. A numerical simulation process is comparatively analyzed with reference to field monitoring data. ［Result & Conclusion］When the construction interval between the left and right lines is within 200 rings, the disturbance effect from dual-line construction may have a superimposed impact, potentially causing excessive deformation of the surrounding soil and building structures, thus jeopardizing the usage safety. Implementing secondary grouting reinforcement within 3 m radius around the tunnel reduces the negative bending moment in the building floor slabs and the columns closest to the tunnel by 45.01%, while reducing the extent and magnitude of ground surface and surrounding building deformation within the design limits, indicating that the secondary grouting can effectively mitigate the stratum disturbance effects caused by shield tunneling. Field monitoring results confirm that soil and pile foundation deformations remain within acceptable limits during the shield tunneling.

［Objective］Advancing urban rail transit four networks (mainline railways, intercity railways, suburban railways, and urban rail transit) integration is an urgent need for China to promote new urbanization with metropolitan areas as the main spatial carrier. Therefore, it is necessary to study the key issues in planning for the integration of four networks. ［Method］Based on the technological and economic attributes of urban rail transit and the core objectives of network integration, the concept of four-network integration planning is proposed. The scope of the integration planning is defined from the dimension of urban rail transit on the basis of a systematic metropolitan area scope sorting. The primary forms of four-network integration are clarified according to the functional means and passenger flow characteristics of various levels of urban rail transit. The basic methods and technical points for four-network integration are presented at three levels: network, line, and node, with practical case studies. ［Result & Conclusion］The planning for the four-network integration is a scientifically sound implementation arrangement aligned with the stages of urban and transport development. The scope of four-network integration planning typically covers contiguous developed areas within metropolitan regions, with core areas of mutual connectivity and permeability generally within a 30 to 40 km radius spatial coverage from metropolitan area central city. The main forms of four-network integration are complementary integration and compensatory integration. Regarding the integration techniques, the network levels focus on functionalities, the line levels emphasize corridors, and the node levels target hubs.

［Objective］The operation of virtual marshaling trains (abbreviated as V-train) in urban rail transit meets the construction requirements for green energy conservation and green intelligence integrated development projects. In order to solve tracking interval control problems of V-train operation, the main factors affecting the virtual marshaling interval distance control should be determined. ［Method］Aiming at the V-train operation control technology, a tracking relative speed protection model for V-train is established based on its interval protection principle and signal system scheme. The influencing factors of interval distance control are analyzed through calculation parameters. The technical characteristics and engineering application advantages of virtual marshaling are also summarized. ［Result & Conclusion］Main factors affecting the tracking distance between the front and rear V-train are the action response time of the control equipment on the tracking train and the train running speed. V-train application values such as short tracking distance, high train running efficiency and flexible transportation organization are exhibited.

［Objective］The construction of shallow-buried pipe curtain structure may disturb the stratum and cause ground deformation. Therefore, it is necessary to study the influence of pipe curtain structure jacking sequence on land subsidence in order to reduce the disturbance of soft soil stratum caused by the jacking of pipe curtain groups. ［Method］Taking the shallow-buried tunnel section of Luzhou Avenue in Hefei City as an example, the land subsidence caused by steel pipe curtain jacking construction is monitored; combined with the finite difference model, the influence of the steel pipe curtain jacking sequence on land subsidence is analyzed. Based on the monitoring data, the actual jacking conditions and the finite difference model, the differential effects of different steel pipe curtain jacking construction schemes on ground deformation are analyzed, and the steel pipe jacking sequence is optimized. ［Result & Conclusion］Compared with steel pipes of the upper row, the jacking construction of the lower row steel pipes has a greater impact on land subsidence. Therefore, the jacking construction scheme for the overall steel pipe curtain should first jack the upper row of steel pipes, then the vertical steel pipes on both sides, and finally the lower row of steel pipes; while the jacking construction of the transverse steel pipes should start from the middle, and then jack the steel pipes alternately in sequence; the vertical steel pipes on both sides should be jacked from top to bottom, and the steel pipes at the same level should be jacked simultaneously.

［Objective］In urban subway tunnel projects, it is common to encounter shallow-buried hidden karst caves in the tunnel arch. Therefore, it is necessary to study the strata response of subway tunnel construction under such condition. ［Method］The indoor model test is used to simulate the tunnel excavation process. By analyzing and monitoring the deformation of surrounding rock, release of soil pressure, internal force of primary support arch and ground settlement laws during tunnel construction, the disturbance effect of tunnel construction on karst strata is studied. ［Result & Conclusion］Under Grade IV surrounding rock, when the excavation tunnel span is 6.52 m, the tunnel arch cave diameter is 4 m, and the net distance from cave bottom to metro tunnel top is 2 m, the surrounding rock of the hidden cave in the tunnel arch could maintain stability under mechanical excavation of the tunnel, with no surrounding rock instability and damage. Under the condition with vault cavity, the change amount of surrounding rock soil pressure at the tunnel vault is significantly smaller than that under the condition without cavity, and the final value of surrounding rock soil pressure in the former condition is 53.8% of that in the latter condition. The existence of hidden cavity in the arch will increase the range of ground settlement, and the peak ground settlement value directly above the top of the excavation tunnel is 1.73 times that under the condition without cavity. When the tunnel vault develops cavity, the axial force value at the arch vault is 120.3% of that under the condition without cavity, and the bending moment value at the vault is 53.3% of that under the condition without cavity.

［Objective］Metro wheel polygonal wear causes vehicle vibration, affecting the smoothness and comfort of the vehicle operation. The existing static detection methods for wheel out-of-roundness consume a lot of manpower and material resources, a dynamically monitoring for the wheel polygonal wear severity is required. ［Method］A dynamic simulation model of whole-vehicle rigidity and sub-rail foundation flexibility is established; a wheel polygonal order characteristic analysis method based on rail vibration acceleration is proposed; the wheel polygonal wear evaluation index is analyzed and verified based on measured data. ［Result & Conclusion］The wheel polygonal degree index K is less affected by track irregularity and can quantitatively reflect the degree of wheel out-of-roundness; the wheel polygonal amplitude calculated based on the evaluation index K has better consistency with the actual wheel circumferential radial runout amplitude.

［Objective］With the continuous development of the rail transit industry, its operation scale and safety requirements are constantly increasing. To address the issues of low efficiency, missed and false detections in the manual inspection of EMU (electric multiple unit) brake pads, it is necessary to study visual positioning detection methods for EMU brake pads. ［Method］A visual positioning detection method for EMU brake pads based on deep learning is proposed. To address the issue of indistinct image features in real-world scenarios, based on the Faster R-CNN (region conventional neural network) algorithm, an edge detection branch is introduced, and a target edge loss function is added to the loss function, integrating edge information from an auxiliary network. Bilinear interpolation is used to calculate feature pixel values, preserving more feature information of the EMU brake pads. ［Result & Conclusion］The improved Faster R-CNN model proposed here can handle details at the edges, accelerate network convergence, and learn more edge features of the EMU brake pads. Through the bilinear interpolation method, the misalignment errors of target features during ROI (region of interest) pooling quantization process are reduced. The proposed brake pad detection method achieves an average precision of 98.42% and an FPS (frames per second) of 27.77%.

［Objective］In view of the shortcomings that the existing urban rail transit system unable meeting the requirements for passenger flow data real-time transmission, solutions for real-time passenger flow data transmission, analysis, and storage are studied. ［Method］Current situation of urban rail transit passenger flow and traditional automatic fare collection (AFC) system are introduced; the real-time passenger flow monitoring system of urban rail transit based on cloud platform architecture is analyzed from the perspectives of system architecture, data transmission, and functional application etc.. ［Result & Conclusion］Based on the existing conditions of the current urban rail transit cloud platform architecture and AFC system, the transmission and processing of real-time passenger flow data can be realized by using existing hardware resources and communication channels without increasing terminal collection equipment, hardware equipment and transmission capacity. By using the ticket card data collected by AFC gate, a data interface directly connected to the network center is added to the station computer (SC) end, aiming to realize real-time upload of the ticket card counting data to the network center for analysis and processing, thus achieving business functions such as real-time passenger flow monitoring, passenger flow prediction, and emergency decision-making assistance.

［Objective］Construction deviation can affect project outcomes to varying degrees, making it necessary to study the impact of such deviations on the structural dimensions and vibration reduction performance of steel spring floating slabs. ［Method］Focusing on the on-site construction deviation issues during the cast-in-place steel spring floating slab installation in curved sections of metro tunnels, a multi-process mapping theoretical model is established using mathematical geometry methods. By considering deviation combinations of different working conditions, the deviation ranges for the base and floating slab thicknesses are analyzed. Within these ranges, a dynamics model is built using ABAQUS software to evaluate the impact of construction deviations on vibration reduction performance. ［Result & Conclusion］When the tunnel centerline deviates, the base thickness ranges from 75.72 to 281.75 mm, and the floating slab thickness ranges from 278.28 mm to 325.00 mm. Within the base thickness deviation, the peak of the rail vibration response is concentrated in the low-frequency range below 12.50 Hz. The greatest impact on vibration reduction performance occurs when the base thickness is 65 mm, reducing the vibration reduction performance by 23.90%. Within the floating slab thickness deviation range, the peak of rail vibration response is concentrated in the low-frequency range below 3.15 Hz. The greatest impact on vibration reduction performance occurs when the floating slab thickness decreases to 45 mm, reducing the vibration reduction performance by 24.24%.

［Objective］In order to further explore the production operation and business management model in line with the actual operation of urban rail transit, ensuring the scientific process and optimization of the station management mechanism and management capacity, it is necessary to study the smart station management model under fully automatic operation (FAO) conditions. ［Method］Taking into account the current planning and construction situations for FAO and smart stations, a smart station management model under FAO conditions is discussed. According to the characteristics of FAO system and smart station, the management model of smart station under FAO is deeply analyzed; by comparing and analyzing the management models of traditional station and FAO smart station, suggestions for the FAO smart station management model are proposed. ［Result & Conclusion］Under FAO conditions, the regional management of smart stations is better than the natural station management of traditional stations, and can effectively strengthen the on-site business guidance. In addition, it is necessary to combine the new technology features of FAO system and smart stations to comprehensively improve the staff's capabilities in station service management, safety management, emergency management, organization management and personnel management, effectively ensuring the operational service quality.

［Objective］In order to ensure train operation safety and passenger comfort, it is necessary to study the chang-ing laws of aerodynamic force and pressure inside the city railway train when passing through the variable cross-section positions in the tunnel (entering the platform, running in the tunnel, and passing through the intermediate air shaft). ［Method］Taking the 8-carriage city railway train as an example, a numerical calculation model is established. A numerical simulation study on the aerodynamic performance at the variable tunnel cross-section is carried out, and the changes in the train body surface pressure, tunnel wall pressure, train aerodynamic force, and pressure inside the train are analyzed respectively. ［Result & Conclusion］The changing laws of train body surface pressure and aerodynamic load are as follows: the surface pressure and lateral force with train entering the station > the surface pressure and lateral force with train passing through the intermediate air shaft > the surface pressure and lateral force when the train runs into the tunnel. The train body surface pressure amplitude is linearly related to the 1.4 ~ 2.0 power of the train running speed; the tunnel wall pressure is linearly related to the 1.79 ~ 2.10 power of the train running speed; the train body lateral force is linearly related to the 1.8 ~ 2.0 power of the train running speed, and the overturning moment is linearly related to the 1.6 ~ 2.0 power of the train running speed. The air-tightness design of the city railway train can meet the human comfort standard requirements, namely the pressure change inside the car at the variable tunnel cross-section positions shall not exceed 800 Pa per 3 seconds and 500 Pa per 1 second.

［Objective］In order to reduce the ground disturbance when the shield tunnel underpasses buildings, it is necessary to study the settlement control effect of grouting reinforcement during shield tunneling under the buildings. ［Method］Taking the shield tunnel of Hangzhou Metro Line 12 passing under the pile foundation building in a certain section of Xiasha Road as an example, and based on the FLAC 3D finite difference software, two methods of deterministic analysis and reliability analysis are adopted respectively to evaluate the effectiveness of grouting reinforcement measures in controlling foundation settlement caused by shield construction. ［Result & Conclusion］In the deterministic analysis, both the on-site measured data and the numerical analysis results show that the maximum building foundation settlement occurs on one side of the tunnel that is first excavated; grouting reinforcement technology can effectively reduce the building foundation settlement caused by shield excavation, making the building settlement value meets the specification design requirements. In the reliability analysis, the cohesion and internal friction angle are used as random variables, and the Latin hypercube sampling-response surface-finite difference method is adopted to evaluate the control effect of grouting reinforcement. It is found that the grouting reinforcement can effectively improve the structural reliability of the building foundation and significantly reduce the uncertainty of the calculated settlement value. Compared with the deterministic analysis method, the reliability analysis method is more reasonable in describing building foundation structure safety by taking the uncertainty of the parameters into account, and can be used to evaluate the effectiveness of control measures in complex shield tunnel excavation projects.

［Objective］During train operation, there is random vibration in the wheelset, which causes position changes of the wheel-rail contact point, thereby affecting the measurement results of the wheel-rail force. To solve this problem, a measurement compensation method is proposed. ［Method］The influence of wheel-rail contact point position changes on the force-measuring wheel, and the compensation scheme for wheel-rail force measurement after wheel-rail contact point position change are introduced. The validity of the wheel-rail force measurement compensation scheme considering wheel-rail contact point position changes is verified through simulation analysis. ［Result & Conclusion］After adding the U.S Grade V track irregularity spectrum excitation, the maximum offset of the wheel-rail contact point position is 17.53 mm, and the maximum relative error of the vertical force reaches 22.85%; after adopting the proposed measuring compensation method, the maximum relative error of the wheel-rail vertical force decreases to 8.02%, and the measurement accuracy is significantly improved. After superimposing the sharp bend irregularity spectrum, the maximum derailment coefficient reaches 1.016 8, exceeding the allowable limit; the derailment coefficient calculated by the non-offset calibration coefficient is 0.347 7, and the derailment coefficient calculated with the proposed compensation method is 0.962 2, indicating that this method can accurately reflect better the train running safety status.

［Objective］During the operation of urban rail transit, the train operation induced vibration can damage buildings and precision instruments along the line, and even affect people's daily lives. Therefore, effective vibration reduction measures need to be studied. ［Method］The long-mileage open-cut section tunnel of Xiong'an Rail Transit R1 Line is taken as an example, which uses rubber soil instead of plain fill. With numerical simulation method, a corresponding tunnel-stratum finite element model is established in ABAQUS software to analyze the vibration isolation effect of different rubber soil damping ratios on open-cut tunnels. ［Result & Conclusion］Using rubber soil with a damping ratio of 0.04 for backfilling can reduce the ground vertical vibration acceleration by 6.2% and the vibration acceleration level by 1.1% at most; using rubber soil with a damping ratio of 0.06 for backfilling can reduce the ground vibration acceleration by 11.4% and the vibration acceleration level by 1.3% at most. The vib-ration isolation effect of rubber soil with the above two damping ratios on open-cut tunnels is quite obvious. At the same measuring point, the reduction amount of vibration acceleration and vibration acceleration level by rubber soil with a damping ratio of 0.06 is generally greater than that by rubber soil with a damping ratio of 0.04, with the maximum reduction rates reaching 5.2% and 0.667% respectively.

［Objective］To address the issue of cutterhead damage and subsequent work stoppages caused by unidentified obstructions during the construction of Zhengzhou Metro Line 3 tunnel, it is essential to study comprehensive construction methods for shield receiving in water-rich silty sand stratum. ［Method］A comprehensive construction plan for shield receiving is introduced, incorporating techniques such as the double-ring freezing method, active dewatering, mining methods, and shield empty push construction. The temperature variation characteristics of freezing and key construction technologies are analyzed using on-site monitoring data. ［Result & Conclusion］The comprehensive construction plan is proven to be safe and effective for dealing with shield receiving in water-rich silty sand stratum conditions. Adopting double-ring freezing method combined with active dewatering could effectively prevent issues related to water and sand inflows in mining method tunnels. During the steam thawing process of the inner ring freezing wall, the temperature of the outer ring freezing wall increases by approximately 5 ℃. When employing the shield empty push method through a mining method tunnel that is not fully thawed, the maximum shield thrust is 26 500 kN, which is less than the theoretical value of shield push resistance. At this point, the ground displacement and tunnel deformation all meet control requirements. During shield empty pushing, the temperature at the interface between shield casing and partially thawed inner ring soil remains around 3 ℃. When crossing the frozen zone using the mining method, different levels of land subsidence are observed near the tunnel, while the soil layer subsidence trend far away from the tunnel remains relatively stable.

［Objective］Urban rail transit uses a 2.4 GHz frequency band vehicle-ground wireless communication system for the signal system, which is extremely susceptible to interference from communication operators, civilian WiFi, personal hotspots, Bluetooth, RFID (radio frequency identification) technology and other equipment, resulting in frequent vehicle-ground communication interruptions and even affecting the normal operation of trains. Therefore, it is necessary to study the anti-interference performance and application transformation measures of the 2.4 GHz frequency band in CBTC (communication-based train control) vehicle-ground wireless communication system. ［Method］The problem of train emergency braking failure caused by vehicle-ground communication interruption, as well as the solution to improve anti-interference performance are introduced; taking a certain metro line in Hangzhou as example, a 5.8 GHz frequency band transformation project is carried out through on-site testing and other methods. ［Result & Conclusion］The anti-interference performance is improved by taking various measures such as investigating and rectifying fixed interference sources, installing shielding devices, and adjusting the frequency bands of communication operators. Based on current situations of the 5.8 GHz frequency band application and channel occupancy in the line network, the vehicle-ground wireless networking mode is transformed from 2.4 GHz (A network)+2.4 GHz (B network) to 2.4 GHz (A network)+5.8 GHz (B network). After taking a variety of anti-interference measures, vehicle-ground communication failures are alleviated. Through the transformation and application of the 5.8 GHz frequency band, the train emergency braking problem caused by vehicle-ground wireless communication interruption on a certain line of Hangzhou Metro is solved.

［Objective］In order to study the influence mechanism of metro station built environment on the passenger flow of the station, taking metro stations in Kunming city as the example, the influence mechanism of station built environment on the passenger flow from different sources on working days and rest days is analyzed. ［Method］Using Kunming Rail Transit AFC (automatic fare collection) card swiping data and POI (point of interface) data, the passenger flow of the stations is subdivided into generated passenger flow and attracted passenger flow two types. On this basis, daily variation characteristics and spatial visualization analysis are conducted, and influence mechanism models of working days and rest days on different passenger flow types are established. ［Result & Conclusion］The results show that high passenger flow attraction stations are concentrated in the main city area and new town center, and high passenger flow generation stations are distributed in the near and far suburbs of the city. The influence mechanism of station built environment on passenger flow is significantly related to passenger flow characteristics. Land use dominance degree has an inhibitory effect on passenger flow generation but a promoting effect on passenger flow attraction; while the constrained facilities and bus network density only have a significant influence on passenger flow attraction; road network density and leisure facilities have different degrees of influence on the generation and attraction of passenger flow. With the time change from working days to rest days, the influence of land use dominance degree on passenger flow generation disappears, while the influence of bus network density on passenger flow attraction begins to appear.

［Objective］In PBA (pile-beam-arch) method construction, the choice of different arch support schemes significantly impacts the structural mechanics. To ensure the reliability and safety of urban underground structures, it is essential to rigorously monitor the land subsidence. Thus, it is necessary to systematically study the impact law of various arch support schemes on supporting structures and ground deformation. ［Method］Based on Tianhe East Station project on Guangzhou Metro Line 11 and using MIDAS/GTS software, a three-dimensional finite element model is constructed to analyze the land subsidence characteristics and the arch initial support internal force distribution law of various arch support schemes in depth. Meanwhile, field monitoring data of land subsidence is also used to validate the numerical simulation results. ［Result & Conclusion］The calculation results of initial support arches reveal that, compared to the CD (center diaphragm) method, the stepped method results in increases of 6.80% in land subsidence, 9.74% in initial support bending moment, and 14.62% in axial force, all meeting the construction control requirements. Research results of secondary lining arch support show that the alternating support removal method significantly reduces land subsidence with a smaller impact on arch initial support internal forces compared to the sequential support removal method. The scheme of combining CD method for initial arch support with alternating support removal method for secondary lining arch support proves to be advantageous.

［Objective］To address the issues of reduced vibration isolation performance of floating slabs under water immersion, it is necessary to study the impact of train operating speed and steel spring isolator stiffness on vibration reduction under operational conditions. ［Method］Based on fluid-structure interaction theory, a floating slab-immersion-tunnel fluid structure coupled vibration model is developed, incorporating the water-immersed steel spring floating slab and the tunnel. The accuracy of the model is validated using field data. The isolator stiffness and train speed affecting the vibration reduction performance of the water-immersed floating slab under train load action is analyzed. ［Result & Conclusion］Under steel spring floating slab water immersion conditions, changes in isolator stiffness and train operating speed primarily affect the amplitude of tunnel wall vibration, with minimal impact on the distribution of the dominant frequencies. As the stiffness of the steel spring isolators increases or the train operating speed rises, the vibration reduction performance of the floating slab deteriorates more significantly when immersed. When the water depth increases from 80 mm to over 160 mm (the immersion reaches from 1/4 to 1/2 of the slab side space height), the maximum Z-vibration level of the tunnel wall increases by over 10%. When the train operating speed decreases from 80 km/h to 40 km/h under floating slab water immersion conditions, the maximum vibration level of the tunnel wall decreases by approximately 8%, though it remains higher than that under non-immersed conditions. Once the water height exceeds 1/2 of the slab side space height, further reducing isolator stiffness or train operating speed is limited in improving vibration reduction performance.

［Objective］In order to improve the transportation capacity of railway lines, make the trains form a stable virtual formation within the interval, and reduce the communication pressure during the entire marshaling process, it is necessary to study the collaborative control of virtual formation trains based on the event triggering mechanism. ［Method］The control system of virtual formation trains is introduced, and a method based on the above-mentioned collaborative control is proposed. By analyzing the basic concept of virtual formation trains, a dynamic model of virtual formation trains with disturbance in sections is established, and event triggering conditions are set according to the state error during the train operation using the idea of event triggering, and the distributed controller of the following train is designed. The stability analysis of the control system is carried out based on Lyapunov stability theory, and the effectiveness of the algorithm applied to virtual formation is verified by MATLAB simulation software. ［Result & Conclusion］The designed event triggering function can make the virtual formation system asymptotically stable, and the system has avoided Zeno behavior. Under the action of the controller, the following train can keep the same speed as the lead train within 4 s, while reducing the communication pressure, the entire virtual formation train can also maintain a stable tracking distance.

［Objective］In order to timely and accurately grasp the internal stress distribution of continuous welded rails (CWR) and reduce the investment of manpower and material resources in CWR stress adjustment operations, it is necessary to study the issues of CWR stress adjustment. ［Method］The causes for uneven temperature distribution in CWR are introduced, and the characteristics of temperature distribution in CWR are clarified by combining infrared thermal imaging technology; a portable CWR stress homogenization adjustment device is designed and applied in actual projects. ［Result & Conclusion］The random differences in locked rail temperature, and the objective differences in meteorological parameters and materials are the reasons for the uneven temperature distribution inside CWR. On the actual operating line, there is a temperature difference at the position of adjacent fasteners, with a temperature difference of 1.8 ℃, which causes a local temperature stress extreme difference of 2.77 MPa in the steel rail. The portable CWR stress homogenization adjustment device can excite the maximum acceleration value of the rail to 305.944 m/s2, and control the longitudinal fluctuation displacement value of the rail to 0.014 mm. The CWR internal stress is thus effectively released due to the high-frequency excitation.

［Objective］To address the diverse design needs of different products and meet customer requirements for quick design and manufacture of high-speed trains, it is necessary to study demand-driven design methods for rail transit vehicles. ［Method］By collecting, classifying, and summarizing various demands for rail transit vehicles, and performing operations such as sorting, matching, and parameterizing these demands, a demand database is established. For the personalized characteristics of rail transit vehicles, personalized demands are gradually decomposed into various levels and components of the vehicles, forming a demand model. Mapping rules between demands and indicators are constructed using direct mapping, function mapping, and knowledge mapping. ［Result & Conclusion］The proposed demand-driven design method for rail transit vehicles can define and classify the collected demands for rail transit vehicles structurally, normatively, and attributively, forming demand data of different levels, attributes, and vehicle models. Based on customer-specified demands, corresponding rail transit vehicle demands are proposed, which are then mapped to technical indicators of the rail transit vehicles, ultimately obtaining a set of rapid design data for rail transit vehicles.

［Objective］The airflow variation of metro train operating in tunnels affects the air quality and ventilation efficiency within the compartments. Therefore, it is necessary to study the ventilation characteristics of metro train compartments when operating in tunnels. ［Method］Through real-vehicle testing, the dynamic variation of the ventilation parameters such as fresh air volume, exhaust volume in train operation state is studied, and the dynamic performance of the ventilation system is analyzed. Based on the in-situ test data, numerical simulations of the train ventilation system working state at different operating speeds are conducted to further analyze the ventilation characteristics of metro trains during operation. ［Result & Conclusion］The supply and return air in a same compartment are uneven. The supply and exhaust air volumes of each compartment are unbalanced, with the supply air volume decreasing from the train front to the rear, and the return air volume increasing in the same direction. As the train accelerates, the return air volume in the air duct gradually increases, while the fresh air volume gradually decreases. When the train speed reaches 40 km/h, a significant reverse fresh air phenomenon occurs in the air duct. During train acceleration, the fresh air inlet exhibits a larger and continuously decreasing negative pressure, while the return air inlet exhibits a smaller and less fluctuating negative pressure. The increased pressure difference between the fresh air inlet and the return air inlet is the cause for the fresh air reversion.

［Objective］It is aimed to accurately predict the traction energy consumption of urban rail transit trains operating in relative speed mode using support vector machine（SVM）regression and genetic algorithms, ultimately enhancing energy efficiency during train operation. ［Method］First, the dynamics characteristics of urban rail transit train traction operation are analyzed to obtain dynamics physical indicators that reflect the real-time operational state of the trains. It then models the relative speed and position changes between trains to establish a train operation model based on relative speed mode. On this basis, key train operational indicators that directly influence train traction energy consumption are extracted, and SVM regression combined with genetic algorithm is employed to analyze these indicators, enabling precise train traction energy consumption predictions. ［Result & Conclusion］The experimental results demonstrate that the proposed method effectively predicts train traction energy consumption. The prediction accuracy ranges from 92.0% to 99.6%, with a maximum relative error of 2.36%, an average relative error of 1.75%, and a root mean square relative error of 1.52%, outperforming other prediction methods by every indicator value. The prediction results of the design method show minimal fluctuation throughout the entire prediction range, indicating excellent overall prediction stability and strong practical applicability.

［Objective］The zoning fare system is widely used in European rail transit systems, but has not yet been put into practice in many Chinese cities with rail transit operation. Following the rapid urban rail transit construction in China and the accelerated formation of metropolitan areas on rails, it is necessary to analyze the characteristics of the zoning fare system and conduct in-depth discussions on above system adaptability in urban and metropolitan area rail transit of China. ［Method］After investigating the application cases of zoning fare system prices in foreign cities, the practical characteristics of this system are summarized. Taking the Guangzhou metropolitan area rail transit network as an example, a zoning fare system price scheme is proposed. Taking the price of metered fare structure as a reference, the adaptability of zoning fare system in urban and metropolitan area rail transit of China is comprehensively discussed from the aspects of zone scheme demarcation, pricing path setting, fare rule formulation, fare fairness and ticket guarantee capability. ［Result & Conclusion］The results of the research show that the implementation of zoning fare system for metropolitan area rail transit can encourage multiple seamless transfers within the zone, this will be conducive to the integration development of the fare structure and price for metropolitan area rail transit. However, there are great difficulties in zone edges setting and fare rules (basic fares and cross-zone fares) formulating. The zoning fare system also has requirements for the land use form of the region, and may reduce the company′s ability to guarantee fare revenue and change the pricing standards of urban rail transit.