The complexity of deepexcavation construction arises from the influence of various potential risk factors on the construction procedure. To address this issue, this study introduces an intuitionistic fuzzy TOPSIS method aimed at identifying potential highrisk factors. Initially, potential risk factors were determined through an analysis of the failure modes derived from prior excavation accidents, insights from practical engineering projects, and the expertise of engineering professionals. Subsequently, a risk evaluation hierarchy was established, and weights were assigned to experts and criteria using intuitionistic fuzzy numbers. A practical project involving a deep excavation was conducted to validate the feasibility of the proposed method. The results indicate that the TOPSIS method effectively identified highrisk factors. The developed method serves as a valuable decisionmaking tool for the safety risk analysis and control of excavation construction in similar engineering projects.

In response to the relevant issues of urban operation transformation of existing railways under the background of "four network integration," this paper investigates new ideas and models for urban operation transformation of existing railways, taking the Xi'anHuyi railway transformation as an example. First, based on the function of urban railways, this study assessed the construction models and operational characteristics of existing railways for operating urban trains and identified current problems, such as incomplete technical standards, a low degree of network integration, a low passenger flow intensity, and significant operational losses. Second, taking the operation of urban trains on the Xi'anHuyi railway as an example, this study analyzed the transportation organization mode, passenger flow characteristics, and transportation connection methods and explored the applicability of the mixed passenger and freight modes of singletrack urban railways. Finally, this paper proposes optimization strategies for the highquality development of urban railways, including coordinating preliminary planning, optimizing transportation connections, improving operational efficiency, accelerating land development, and overcoming management barriers. These suggestions can provide a reference for subsequent renovation and upgrading of existing railways.

To explore the stress and deformation characteristics of an existing tunnel caused by foundation pit dewatering, a threedimensional numerical model was established based on an actual project. Taking the maximum vertical displacement of the tunnel as the evaluation index, an orthogonal table is used to screen the optimal combination and the main influencing factors. Then, the main influencing factors are analyzed via univariate analysis to study the stress and deformation law of the tunnel. The results of the range and variance analyses showed that the insertion depth of the diaphragm wall was the main factor affecting the maximum vertical displacement of the tunnel outside the pit. Therefore, when a new foundation pit project adjacent to an existing tunnel has a dewatering demand, this factor can be selected first to control tunnel deformation. As the insertion depth of the diaphragm wall increases, the bending moment and deformation of the tunnel decrease. After the insertion depth of the diaphragm wall reaches a soil layer with poor water permeability, the tunnel deformation decreases significantly. At this time, the deformation of the tunnel can be effectively controlled; however, controlling the deformation of the tunnel by increasing the insertion depth is of little significance. The dewatering causes the adjacent tunnel outside the pit to produce "horizontal duck egg" settlement deformation toward the pit, obliquely downward, and the deformation of the tunnel vault and the side arch waist of the adjacent foundation pit should be emphasized during the construction process.

Traditional steel struts cannot be tensioned, and the construction of concrete struts is complex and generates considerable construction waste during the demolition phase. Therefore, prestressed steel struts capable against tensile and compressive stresses have been invented. The performance evaluation results of mechanics, construction adaptability, and cost with a prestressed steel strut capable against tensile and compressive stresses show that its compression bearing capacity is the same as that of a traditional steel strut and equivalent to that of a concrete strut. Furthermore, its tensile and strut stiffness performances are equivalent to those of a concrete strut and superior to those of a traditional steel strut. Its construction convenience is equivalent to that of a traditional steel strut and 20%30% lower than that of a concrete strut. The first concrete strut replaced by a prestressed steel strut capable against tensile and compressive stresses for metro excavations can not only ensure technical performance but also result in better economic and social benefits.

Synthetic sleepers of fiberreinforced polyurethane foam were initially applied in urban railway traffic to adapt to the linear induction motor system, and they have been developed into national and heavyhaul railways in recent years. Synthetic sleepers have been widely researched and applied nationwide owing to their excellent overall performance. The technological development history and standards of synthetic sleepers in China were analyzed and compared with foreign and ISO standards. In addition, the application progress, application problems, and solutions were investigated. Suggestions for the development and prospects of polyurethane synthetic sleepers in China were proposed by combining the requirements of domestic rail traffic with the application problems of synthetic sleepers.

To explore the influence of a cavity on a shield tunnel, a refined numerical model of a shield tunnel, considering ring and longitudinal joints, is established. The variation law of the internal force, deformation, and section safety factor of the segment are investigated under various conditions, such as the depth, area, and location of the cavity. Additionally, the influence of different assembly points of the segment on a tunnel with a cavity behind it is discussed. The results indicate that the order of the adverse effects of cavities at different positions behind the tunnel on structural safety is tunnel waist > tunnel bottom > tunnel top. When the cavity area is 5.0 m², with an increase in the cavity depth, the bending moment and safety factor of the tunnel section at the center of the tunnel top or bottom cavity first decrease and then increase in the opposite direction, and the ellipticity of the segment first decreases to 0 and then increases in the opposite direction. The bending moment is reversed when the cavity depth was 0.3 m or 0.2 m. The safety factor of the section at the center of the left tunnel waist cavity decreases continuously, and the ellipticity of the duct piece and the bending moment increase significantly. When the cavity depth is 0.5 m, the bending moment of the tunnel section at the center of the cavity at the top or bottom of the tunnel is reversed when the cavity area is 3.75 m². The existence of circumferential joints within the cavity reduces the internal force of the tunnel section at the center of the cavity and improves its safety factor. However, its maximum joint opening is 2.03.5 times that of a cavity without a joint. The results provide a reference for the safety evaluation of the cavity behind the lining of a shield tunnel and the selection of assembly points.

To address uncertainties in future operational carbon emissions and carbon reduction targets for urban rail transit networks, this study analyzes operational energy consumption data for the Xi'an urban rail transit system from 2018 to 2022. The carbon emission factor method is employed to calculate operational carbon emissions for the past five years. The index method is then used to predict energy consumption and carbon emissions for the next five years. Based on the binding energy intensity requirements outlined in China's Action Plan for Green Urban Rail Development, we quantitatively analyze the total energy saving target for Xi'an's urban rail transit operations over the next five years. Subsequently, the total carbon emission constraint and carbon reduction target are determined. The research results indicate that approximately 175.9×10⁴ tCO2e of total carbon emissions were generated during the operation of the Xi'an urban rail transit system from 2018 to 2022. Under these conditions, it is expected that approximately 321.6×10⁴ tCO2e of total carbon emissions will be generated over the next five years of operations, with traction and station power consumption being the main sources of carbon emissions. If the comprehensive energy intensity reduction target proposed by the association is achieved, compared with the predicted carbon emissions, the carbon emissions of the entire network are expected to reduce by approximately 13% by 2025; the carbon emissions of the entire network are expected to reduce by approximately 15% by 2027; and in total, carbon emissions are expected to reduce by approximately 10% over the next five years.

This study investigates the reasonable setting of suburban railway curve superelevations in the case of related specifications and standards that are not unified. The principle of prioritizing the allowable values of each superelevation is not clear. By comparing and analyzing the requirements for curve superelevation settings in different codes and by analyzing examples, this paper proposes the maximum and minimum values of design superelevation, the general allowable values for undersuperelevation, oversuperelevation, and difficult situations, and the allowable values for the superelevation slope ratio, taking into account the Code for Design of Railway Track, Code for Design of Suburban Railway, and other industry standards. The priority of design principles of allowable values for different superelevations is obtained, providing guidance for the setting of curve superelevations for new suburban railways and providing a reference for the improvement of industryrelated standards.

This study proposes a solution involving the use of a longitudinally induced ventilation system to solve ventilation challenges in factory buildings within a covered metro vehicle base, where natural ventilation is impractical and traditional horizontal ventilation systems are difficult to implement. We first created a threedimensional model for the longitudinally induced ventilation system, analyzed the impacts of the induced jet fan installation spacing and height on the airflow within the factory building based on numerical simulation results, and validated the proposed system against actual engineering conditions. The results indicate that the best overall and workstation ventilation effects can be achieved with installation spacings of 20 and 25 m, respectively, along with heights of 8 and 6 m, respectively, for the induced jet fans inside the factory building. The field tests agreed well with the simulation results. This study provides a theoretical basis for the application of longitudinal ventilation systems in engineering applications.

Subway traction energy consumption can be reduced by optimizing subway timetables. To solve the problem of the impact of passenger flow fluctuations and train delays on the actual energysaving rate, this study proposes a Dueling Deep Q Network (DQN) deep reinforcement learning timetable optimization algorithm combined with a realtime subway power supply current flow calculation model. An interval iterative optimization model based on the spatiotemporal distribution of the dynamic passenger flow was established to suppress the impact of passenger flow variation. The Adaptive Moment Estimation (Adam) and root mean square propagation (RMSProp) methods were applied to predict the Qnetwork and target Qnetwork as well as improve the convergence speed of the model. While minimizing passenger transfer, waiting, and total travel times, this model allows for the seamless switching of energysaving timetables. The test results for Suzhou Line 4 demonstrate the effectiveness of the proposed method. Under the conditions that the arrival time deviation at transfer stations was less than 2 s and the overall operating time of trains remained unchanged, the traction energy saving was 5.27%, and the train kilometer energy consumption decreased by 4.99%.