Subway Project Research Articles

Adaptability of a Reinforced Concrete Diaphragm Wall Cut by Disc Cutter

On the background of a subway project in Suzhou City of Jiangsu Province and targeting the engineering difficulty of disc cutters cutting reinforced concrete walls, this paper illustrates the adaptability of a reinforced concrete diaphragm wall cut by disc cutter through conducting related laboratory tests and numerical simulations. When cutting a reinforced concrete diaphragm wall, the cutter should use the low-penetration depth excavation pattern with the depth of the penetration kept within 10 mm/r. In order to keep the torque in a small floating range, the cutterhead driving speed and thrust should be strictly controlled during the cutting period. Three types of fracture surface after the cutting operation, namely, single-side rolling destroy, double-sided rolling destroy, and brittle destroy. The percentage of the length of the cut steel bar smaller than 60 cm can reach 44.2% when the driving parameters of the disc cutter are well regulated. The simulation results show that the deeper the penetration, the more unstable the cutting load. The relationship between the normal force of the disc cutter and the penetration depth was linear, and the trend of the simulated value was comparable with the experimental one, which ensures the rationality of this pattern. The cutter spacing had little impact on the cutting results when it was wider than 80 mm.

Analysis and Field Measurement on the Internal Force Variation Laws of Steel Pipe Columns in Subway Stations

Steel pipe columns are an important component in subway station construction and with stand stress state and internal force during the construction process. Based on the engineering background of Beijing subway, this paper introduces the geological conditions, station structure types, and internal force monitoring of steel pipe columns of 10 subway stations constructed by the PBA method. The field monitoring indicates that the greatest change in the internal force of the steel pipe column occurs during stage 1 (beam, primary support, and secondary lining buckle arch construction stage), no matter pile foundation station or strip foundation station, which accounts for about 60% to 65% of the total axial force. When the left and right spans are not synchronously arched or excavated, the steel pipe column is subjected to uneven forces and bears a large bending moment is produced. When the depth of overburden is between 7 m and 15 m, the internal force of the steel pipe changes positively correlated with the overburden depth. During the construction process, the internal force of the steel pipe varies widely in the silty sand stratum. Also, the steel pipe columns in stations affected by groundwater bears about twice of the axial force compared with other stations are not affected by groundwater. In addition, the construction period is also a factor that affects changes in internal forces. This research is conducive to update the database of the world subway projects and can serve as a practical reference for similar geological condition.

Construction and Quality Control of Subway Wet Loess in Concealed Tunnel Based on Particle Swarm Optimization Algorithm

To reduce urban pressure, urban rail transit has become an effective way to reduce traffic congestion, mitigate traffic accidents, reduce environmental pollution, and improve commuting efficiency. Subway as the main means of urban public transport travel, in recent years by people’s favor, although the construction industry of rail transit is developing rapidly and the industry scale is expanding, but because the construction of rail transit construction projects is very difficult, especially in the wet loess within the concealed excavation tunnel, but also frequent accidents, and the quality of the project is not easy to guarantee, so the underground railroad wet loess within the concealed excavation tunnel construction technology is poor. Therefore, it is especially important to study the construction technology and project quality management of underground railway concealed tunnel in wet loess. In this paper, based on the in-depth study of the basic principle of quantum particle swarm optimization calculation and the realization of key engineering technologies, the particle swarm optimization algorithm is programed using MATLAB software, and the coding scheme, operation specification, and operation parameters are designed. Then, combined with the particle swarm optimization algorithm and assisted MATLAB software, the main analysis of the construction and quality control of wet loess in concealed tunnels of subway projects was carried out, mainly by systematizing the relationship between the three major elements of subway project schedule, cost, and management and the construction and quality control of wet loess in concealed tunnels of a subway, and concluded that the construction and quality control of wet loess in concealed tunnels of the subway needed schedule. It is concluded that the construction and quality control of subway wet loess tunnel requires stable schedule, adequate cost budget, and management personnel.

Prediction of shield machine posture using the GRU algorithm with adaptive boosting: A case study of Chengdu Subway project

Shield machine deviation from the design tunnel axis (DTA) causes dislocation and damage of the segments and may lead to poor tunnel quality, which is a primary concern in tunnel construction. Therefore, it is necessary to predict the shield machine posture dynamically and assist the operator in adjusting the tunneling parameters in advance. Based on the tunneling data of five earth pressure balance (EPB) shield machines, a novel method for predicting shield machine posture, mainly composed of adaptive boosting (AdaBoost) and gated recurrent unit (GRU) algorithms, is proposed in this paper. In parallel, a data preprocessing algorithm is developed for the original tunneling parameters, including three phases: data extraction, data compilation, and data normalization. The hyperparameters of the model were determined using the grid search and cross-validation technology. The actual deviation case test shows that once the model predicts that the shield machine posture will deviate significantly from DTA, it can issue a warning in advance and assist the machine operators in optimizing tunneling parameters for a better trajectory. Then, the model prediction results were compared with the benchmark algorithms. The results reveal that the GRU algorithm is conductive to capture the trend of the time sequence, and the AdaBoost algorithm is beneficial for improving the fitting ability of the regression model. Finally, we found some association rules of tunneling parameters that affect the posture of shield machine.

Applying Project-based Learning Method to Teaching Subway Project Management Course

Applying Project-based Learning Method to Teaching Subway Project Management Course

Metro Engineering Project Schedule Optimization Based on Wireless Network Communication and BIM Model Algorithm

BIM (Building Information Modeling) is to create models based on various related information in construction projects and use simulation virtual technology to model actual building information. It is not only the integration of digital information but also the application of digital information in engineering construction. Digital models can be used to plan and simulate the whole process of construction projects scientifically and accurately. In the process of project construction, wireless network communication technology can provide a good basis for collaboration, which is essential for the control of project progress, task scheduling, and systematic communication between all parties. This article introduces the LTE wireless network communication technology and network coverage plan, summarizes the cost and schedule control principles of construction projects, analyzes the factors that affect the construction schedule in subway construction, and introduces the application of BIM technology in subway construction schedule control. Taking the construction of Section XX of Line 1 of City A as an example, a simulation experiment was carried out, and the optimization effect was evaluated with SPI and CPI indicators. The final experimental results show that it is meaningful to use the BIM model algorithm to optimize the subway project. In the simulation experiment, the corresponding construction period saving rate after completion of the project is 6.94%.

Could Havana Have a Subway? The Ongoing Havana Subway Project

Could Havana Have a Subway? The Ongoing Havana Subway Project

Assessing Safety Risk Management Performance in Chinese Subway Construction Projects: A Multistakeholder Perspective

The rapid development of subway projects in China presents significant safety risks to those involved. Building on the previous empirical research that identified and classified the safety risks of these projects, the aim of this paper is to assess the safety risk management performance in Chinese subway construction projects from a multistakeholder perspective. Questionnaire surveys and semistructured interviews were conducted with three hundred and ninety-nine and eight construction professionals, respectively, who worked on subway construction projects in southeast China. The results indicate that the top five areas of safety risk management performance are related to construction plan development, management of high-risk construction works, hazard identification and communication, government-related factors, and client-related factors. In contrast, the bottom five areas of safety risk management performance are related to engineering consultant-related factors, the site’s natural environment and weather conditions, regular tests, machine calibration and maintenance, site construction schedule, and construction preparedness. The relationship between this safety risk management performance and the perceived importance of each risk factor is also reported, identifying priority areas for improvements on these projects. These findings contribute new conceptual insights to the paucity of research on the safety risk management performance of Chinese subway construction projects from a multistakeholder perspective. The results also provide new practical insights for policymakers and project managers to help them develop more effective and focused strategies to further improve the safety performance of these major projects.

Research on Case-based BIM Aided Design List Management

In recent years, China has entered a period of rapid development of urban rail transit construction. Building information modeling technology (BIM) has been widely used in the design stage of urban rail transit engineering, but there is a waste of BIM design resources, and there is a lack of scientific and systematic BIM technology application mode and management methods. Based on this, this article summarizes six BIM application modes that are prone to problems in design and contributes greatly to construction, and summarizes the work content, management methods and application effects of each application mode. Then, we investigated the charging situation of the aforementioned BIM application mode for subway projects of five domestic companies, which provided a reference for the choice of BIM application mode. Finally, combined with the construction of Tianjin Line 5, it is demonstrated that the use of BIM aided design list management can maximize the application of BIM technology to value points in the design stage under the condition of limited construction capital investment, which can effectively improve the effect of BIM application, Capital utilization rate and project management level.

Intelligent Performance Evaluation of Urban Subway PPP Project Based on Deep Neural Network Model.

Neural network refers to an algorithmic mathematical model that imitates the behavioral characteristics of animal neural networks and performs distributed information processing. This kind of network depends on the complexity of the system and needs to adjust the internal node relationship, so as to achieve the purpose of processing information. With the continuous development of the economy, the transportation problem needs to be solved urgently, and the urban subway has emerged at the historic moment. The subway is a fast, large-capacity, electric-driven rail transit built in the city. The advantages of the subway provide conditions for the mitigation of urban traffic, due to the large number of cars, traffic jams, frequent accidents, and serious environmental pollution. In the city center, there are more cars and less space, and the parking lot is not commensurate with the number of cars, making parking difficult. This paper aims to study the intelligent performance evaluation of urban subway PPP projects based on deep neural network models. The subway project has a large investment, a long period, and a wide range, but the development time of the subway in China is relatively short. In order to promote the stable progress of subway projects, it is very necessary to conduct intelligent performance evaluation on subway projects. This paper compares and analyzes the basic characteristics of the PPP model and verifies the applicability and necessity of the PPP model in urban subway transportation projects. Through the investigation of relevant literature, this article puts forward the research content of the social impact assessment of subway projects. The experimental results of this paper show that, from the perspective of whether it is necessary to evaluate the performance of PPP projects, 65% of people think it is very necessary, and 22% think it is more necessary. 3% of people think it is unnecessary, and 10% of people hold an indifferent attitude. These data show that the intelligent performance evaluation of urban subway PPP projects has exploratory significance for urban infrastructure design and construction.

Discussion on the Factors Affecting the Cost of Subway Project and Its Control Strategy

Discussion on the Factors Affecting the Cost of Subway Project and Its Control Strategy

AUTOMATIC IDENTIFICATION AND QUANTIFICATION OF SAFETY RISKS EMBEDDED IN DESIGN STAGE: A BIM-ENHANCED APPROACH

Design stage plays a decisive role in safety risk management of the whole life cycle for construction projects. However, existing research mostly pay attention to post-accident management and lack pre-management consciousness. Based on the concept of design for safety (DFS), this paper explains how design optimization can enhance the safety performance for construction projects. Firstly, use accident causality theory and trajectory crossing theory to clarify the logical relationship between safety accidents and design process. Then, identify risk sources of safety accidents in deep foundation pit of subway projects and form a safety management knowledge base. Thirdly, based on design and review rules in the knowledge base and improved FEC risk quantification method, quantify the design oriented subway construction safety risks. Finally, use BIM secondary development technology to realize automatic examination and visualization of safety risks. A case study was conducted to verify this research framework. This paper can be a supplement to the existing risk management theoretical research.

Managing Safety Hazards in Metro Subway Projects under Complex Environmental Conditions

Managing Safety Hazards in Metro Subway Projects under Complex Environmental Conditions

Investigating institutional barriers and opportunities to an integrated approach for transport and spatial development: Mega urban transport development in a rapidly developing city, Seoul

ABSTRACT In response to rapid growth, megacities make large investments in mega urban transport projects. To ensure positive social outcomes, e.g., accessibility for all, an integrated approach to transport and spatial development is needed. This paper identifies the institutional barriers and opportunities to using an integrated approach, using Ostrom’s Institutional Analysis and Development Framework (IAD). We investigated a metro (subway) project in Seoul, South Korea, a rapidly-growing metropolis that has established an extensive transport network. Our analysis revealed that various rules have led to imbalances between transport and spatial planning, contributing to undesirable outcomes. Incongruence in scope between transport and spatial development, a lack of clear procedures for integrated planning, and institutional ambiguity regarding the responsibilities of the various actors affected social outcomes. We conclude that achieving desired social outcomes from mega urban transport projects requires institutional harmonization across sectors and levels, and local capacity to operationalize an integrated approach.

Experimental study and analysis on seismic performance of special-shaped steel reinforced concrete column frame

Using a prototype special-shaped steel reinforced concrete (SRC) column frame from a subway project, a low-cycle reversed loading test on 1/10 scale, 2-bay, 2-story special-shaped SRC column frame was carried out. The load-bearing capacity, stiffness and degradation, ductility, hysteresis and energy consumption characteristics were analyzed. A finite element model (FEM) of the frame was formulated to analyze the stress and the deformation behavior. The analysis and experimental results were compared to one another. The results show that the hysteresis loop of the frame is well defined and the elastic–plastic deformation capacity is ideal for seismic collapse resistance. The numerical simulation results are in good agreement with the experimental test results. The second story of the special-shaped SRC column frame exhibited the most damage in the loading process, therefore it should be further evaluated and optimized.

Research on the Reuse of Discharged Soil from EBP Shield Tunnels in Synchronous Grouting Material

Great practical significance and engineering application value can be achieved when the large amount of discharged soil produced by EPB shield tunnels is recycled and comprehensively utilized. As one of the key processes of shield construction, synchronous grouting needs a large amount of bentonite, cement, fly ash, sand, and other materials. The research on the reuse of shield muck as synchronous grouting material is carried out based on Zhengzhou subway project. The physical properties and phase of the discharged soil from EPB shield tunnels are studied by using laboratory tests and XRD. The statistics show that the shield muck meets the performance requirements of bentonite and fine sand in synchronous grouting materials. The optimal grout ratio of the reused muck is obtained based on the optimization idea of multiobjective programming by MATLAB. Considering the combined effect of seepage field, stress field, and the timeliness of the grout, the influences of grouting pressure and the filling rate of synchronous grouting on surface settlement, plastic zone of strata, and segment deformation are analyzed by using finite difference method. The results prove that the surface settlement and segment deformation can be better controlled when the grouting pressure is at 0.18 MPa and the grouting rate is at 120%–150%.

Time Savings vs. Access-Based Benefit Assessment of New York’s Second Avenue Subway

AbstractUnder the current practice of benefit-cost analysis, the direct economic benefits produced by a newly built transit facility are assessed based on how it affects travel time and various costs that are associated with transport needs and travel behavior. However, the time-saving-based benefit calculation approach has been questioned and criticized. Given the strong correlation between accessibility and land value, we propose the access-based land value benefit assessment as an alternative, and apply this assessment method to analyzing the Second Avenue Subway project in Manhattan, New York. The primary principle of the access-based method is that the economic value of a transport project’s intangible gains is largely capitalized by nearby properties’ value appreciation, which is directly caused by improved transport accessibility. We find that: (i) the actual travel time saving is lower than originally forecast; (ii) a strong positive correlation between residential property value and job accessibility by transit is observed; (iii) the appreciation in sold property value and rented property value both far exceed total project cost; and (iv) such results support the decision to approve and construct the Second Avenue Subway.

Private Returns to Public Investment: Political Career Incentives and Infrastructure Investment in China

Why do politicians who have short tenure expectations have incentives to invest in long-term infrastructure projects? This mismatch between politicians’ short tenures and the long-term needed for infrastructure projects to come to fruition is generally expected to result in underinvestment in critical infrastructure. However, recent data show that China makes massive investments in large-scale, long-term transportation projects. By proposing a political exchange model, we demonstrate a fundamental synergy between the incentives of short-term mayors and of provincial leaders that is realized as a result of subway projects. With both a difference-in-differences design and a fuzzy regression discontinuity design, we show that subway projects significantly increase the promotion chances of city mayors. Additional tests also confirm the mechanism of our theory. Mayors who obtain subway projects deliver economic benefits to provincial leaders. The provincial politicians’ prospects of promotion are significantly improved thanks to these economic returns.

A BIM-BASED IDENTIFICATION AND CLASSIFICATION METHOD OF ENVIRONMENTAL RISKS IN THE DESIGN OF BEIJING SUBWAY

The subway project safety risk management in China covers design and construction stages. The traditional method for identifying construction safety risks at the design stage requires that engineers work backward, and it relies on engineers having an accurate understanding of complex engineering information, spatial relationships, and rich experience. This paper proposes a Building Information Modeling (BIM) based automatic identification and classification framework for environmental risks at the subway design stage. First, a database of discriminant rules was established in order to achieve the digital expression of the discriminant standards for environmental risks. Second, environmental models and discriminant models were created in order to analyze spatial collisions. Then, the risk discrimination algorithm was embedded in the BIM platform. The program automatically analyzed the collision result-based discrimination rule database and output a list of environmental risks associated with the model. Finally, a shield tunnel was used for practice. As a result, the BIM-based method for automatically identifying environmental risks could improve the efficiency of the special design of safety risks and promote the digital transmission of risk design information throughout the construction process. The method described in this paper provides a reference for the safety risk management technology system in China’s subway projects. This method can also be applied to projects such as underground pipe gallery, power tunnel, and foundation pit, after optimizing the classification rules.

Study on Field Test and Seismic Performance of MJS Joint Microdisturbance Reinforcement on Existing Tunnel

Metro Jet System (MJS) joint microdisturbance reinforcement is often adopted to strengthen and remediate existing tunnels that are severely deformed by under-construction peripheral works, but analysis related to the reinforcement system of tunnel under consideration of seismic effects is insufficient at present. In this work, a field test of MJS joint microdisturbance reinforcement system of existing tunnels was conducted on the basis of a subway tunnel deformation reinforcement project. Then, a numerical simulation study of the seismic dynamic response of reinforcement system was performed in combination with seismic wave direction and intensity. Results show that the MJS joint microdisturbance reinforcement measures can effectively reduce the settlement and horizontal radial convergence deformation of the tunnel. The seismic longitudinal wave significantly affects the vertical displacement of the tunnel, and the seismic-induced vertical displacement of the tunnel increases with the rise in seismic intensity. The seismic transverse wave significantly affects the horizontal radial convergence deformation of the tunnel, and the seismic-induced horizontal radial convergence deformation of the tunnel increases with the rise in seismic intensity. The antiseismic property of MJS joint microdisturbance reinforcement measures on the existing tunnel is not obvious.