Metro Station Construction Research Articles

Assessment of EPS-geofoam as light weight backfilling in the construction of underground metro station: a case study

Assessment of EPS-geofoam as light weight backfilling in the construction of underground metro station: a case study

Temporal-spatial-fusion-based risk assessment on the adjacent building during deep excavation

Foundation pit excavation will inevitably cause uneven ground settlement to pose potential risks to adjacent structures and infrastructures. To better perceive the risk status of adjacent buildings using multi-source information, a temporal-spatial-fusion-based risk assessment (TSFRA) model under the consideration of uncertainty and causality is developed by integrating FAHP (Fuzzy Analytic Hierarchy Process), DGDT (DAG-GNN, DEMATEL method, and topological analysis), and CM (cloud model). More specifically, FAHP handles temporal weights of excavation conditions based on expert knowledge. DGDT determines spatial weights for monitoring points, with DAG-GNN constructing causal graphs in a data-driven manner, DEMATEL handling global interactions, and topological analysis calculating node importance. CM can finally fuse the temporal (excavation conditions) and spatial (monitoring points) weights with settlement monitoring data, resulting in qualitative assessments of the overall risk status of adjacent buildings in uncertain environments. The proposed TSFRA is verified in the case of a Shanghai metro station construction project. Results indicate that the perceived risk of the project is at a relatively low level, consistent with the actual condition. High-risk excavation conditions and locations can be easily identified. There is a trend toward higher risk during the excavation of soft soil layers, and thus some risk control measures can be formulated to avoid potential risk events. In short, the weight determination and fusion method in TSFRA contribute to handling uncertainties in expert judgments and causalities in collected data, which can practically provide more reliable decision-making in excavation-induced risk assessment and control for ensuring the safety of adjacent buildings.

Coupling characteristics of construction safety risk and complicated factors of metro station: a case study of Ningbo

ABSTRACT This paper investigates the coupling relationship and degree of complex factors corresponding to the metro station construction in the Ningbo region. To this end, the interpretative structural modeling (ISM) method, a structural interpretation model, is utilized to develop the coupling connection network of construction risk factors. Moreover, the cloud model theory and coupling degree model are used to calculate the risk factor coupling degree within and between the construction safety risk subsystems. The analysis indicates that the coupling degree of risk factors within and among subsystems is notably high, falling into categories characterized by high coupling and strong coupling. It is also found that the entire coupling system is in a state of high-strength coupling. Therefore, during the construction process, the coupling impact of risk factors must be avoided, and risk factors must be prevented from further developing into risk events. The quantitative evaluation of the coupling degree between and among risk factor subsystems in this study provides a reference for project risk evaluation and facilitates the development of subsequent construction safety measures.

INNOVATIVE TECHNOLOGY FOR THE CONSTRUCTION OF A PYLON STATION OF THE METRO BASED ON THE EXPERIENCE OF USING NATM

Purpose. For quite a long time, the metro station of the pylon type of deep contour interval was considered an underground structure that no longer has development potential. However, after the introduction of innovative technologies during the construction of the Dnipro metro, in particular the New Austrian Tunneling Method (NATM), this design is being used again and has developed further use. The purpose of the scientific article is to analyze innovations in the technology of construction of a three-vaulted pylon metro station from precast reinforced concrete using NATM, which require scientific justification. Methodology. In order to achieve the goal, the traditional technology of constructing a deep contour interval pylon station was revised. An analysis of the features of NATM, which allow it to be used during the construction of a pylon station in strong rock, has been carried out. A step-by-step analysis of the construction of the station was implemented with the involvement of mathematical modeling based on the finite element method. For this purpose, a number of finite-element models of each stage of construction of a pylon-type station have been created. After the numerical analysis, the indicated models were adjusted in accordance with the changes associated with the new construction technology. Findings. The value of the stress-strain state of the pylon station was obtained during the numerical analysis of each stage of construction. Stress analysis proves the possibility of applying innovative construction technology in the case of a pylon station. Originality. On the basis of the performed numerical analysis of the phased construction of a pylon station based on NATM, dependencies were obtained that allow revising the existing concept of the construction of this type of station in strong rocks. The obtained data justify the application of NATM and release the potential of the analyzed underground structure. Practical value. The substantiation of the innovative technology based on NATM allows expanding the scope of its application and successfully carrying out the construction of such complex underground facilities.

Construction of shallow buried large-span metro stations using the small pipe roof-beam method

Construction of shallow buried large-span metro stations using the small pipe roof-beam method

Study on the Mechanical Characteristics and Ground Surface Settlement Influence of the Rise–Span Ratio of the Pile–Beam–Arch Method

The pile–beam–arch method (PBA) method is increasingly being used in the construction of metro stations with complex traffic conditions. The rise–span ratio of the arch not only affects the height of the station, but also affects the rationality of the design of subway stations and the safety of construction. The mechanical response of steel pipe piles with different rise–span ratios and the effect of controlled surface settlement have been investigated in the interactions involved in pile–soil system. In this paper, the finite element model of each rise–span ratio was established, and the rationality of the model was demonstrated by comparing the numerical simulation calculation with the field surface settlement monitoring data. The mechanical characteristics and influence analysis of the surface deformation during the excavation of the cave pile method were investigated. The results show that the maximum axial force of the central pile first decreases and then increases with the increase in the rise–span ratio. The maximum bending moment of the arch decreases as the rise–span ratio increases, and the maximum axial force of the arch is negatively correlated with the rise–span ratio. The maximum axial force of the central pile is located at the bottom plate. Due to the symmetry of the structure, the bending moment of the centre pile is small, but the maximum bending moment of the whole station is located at the side wall of the bottom plate. As the rise–span ratio increases, the surface settlement first decreases and then increases. The construction of the pilot tunnel and the upper arch is the most important factor leading to the surface settlement, so it is necessary to strengthen the soil layer.

Thermal-Mechanical Analysis of a Metro Station’s Concrete Structure

The problem of temperature variation in mass concrete construction is a crucial problem in civil engineering. The problems of the temperature field, damaged areas, and the cracking of the structure during the construction process of concrete pouring are analyzed in this paper. An elastic and damaged constitutive model for concrete and a fully coupled analysis method for analyzing the temperature-stress field was proposed to simulate and predict the construction process of a concrete structure in a metro station. The influence of different concrete compositions and material properties was not taken into account in this study. The results show that the temperature-stress complete coupling analysis method can be applied to the calculation and analysis of cracking in a concrete structure that is caused by internal temperature variations during the pouring process of complex concrete structures. An efficient method and research approach is proposed by this study to analyze the damage and cracking issues caused by temperature changes during the pouring process of concrete structures in metro stations. The area and extent of the damage and cracking during the construction can be predicted and evaluated, and a reference for metro station construction and operation is proposed.

Classification and Development Potential Evaluation of Urban Metro Station Areas Based on Extended Node-Place Model-- A case study of Nanjing Metro Line 1

In the process of changing from the extensive mode to the compact mode of the urban space development in China, metro has solved the problem of high-capacity and rapid transportation in cities. The planning of metro stations needs to be investigated in the context of station types in the process of the urban development. In the research, combined with the development examples of stations and surrounding areas along Nanjing Subway Line 1, the factors such as the classification of station types, the current development potential assessment and so on were investigated based on the extended "node-place" model. And then the scientific and reasonable optimization and adjustment strategies for stations and surrounding areas were proposed, which provides reference for the subsequent planning strategies and development and construction of metro stations and surrounding areas.

Cost and Material Quantities Prediction Models for the Construction of Underground Metro Stations

This paper addresses the gap in the scientific literature regarding construction cost estimates for the construction of underground metro stations. It provides preliminary cost estimation models using linear regression for use by the Greek underground metro public transport authority for planning future extensions to the Athens and Thessaloniki networks. At the same time, it contributes to the body of knowledge by proposing material quantity prediction models and presents a two-stage preliminary cost estimation model for the construction of civil engineering works of underground metro stations. Stage one uses the construction cost budgets of six metro stations in Greece to develop a multilinear regression equation for the prediction of the overall cost for construction of civil engineering works; stage two provides estimates of material quantities using linear regression, key quantity ratios, and artificial neural networks. The data analyzed are from the prior measurements of quantities for the construction of the Chaidari to Piraeus extension of the Athens Metro Line 3. After comparing the actual values of costs and quantities with the corresponding predictions, acceptable discrepancies are observed. All models provide estimates within ±25% discrepancies, which are acceptable at the conceptual planning phase in order to initiate project funding quests.

Numerical analysis of metro station pit dewatering and its influence

The underground water level in Xi’an city is generally shallow, and the excavation of the deep foundation pit mainly needs underground water dewatering. The ground deformation due to the dewatering and its influences should be fully analyzed. The empirical formula estimates the water inflow of the foundation pit, and the process of dewatering and metro station construction is simulated via the finite element method and the theory of soil consolidation according to the field investigation and survey data of the natural geological and hydrological environment. The time of water level falling and recovery, ground settlement, and strata deformation caused by pit dewatering and excavation are predicted. The analysis results of the ground settlement are within reasonable limits and close to the previous metro projects. Finally, the influence of groundwater dewatering on Xi’an Metro Line 14 is discussed. The settlement induced by dewatering for constructing a metro station in the sandy stratum is relatively small, and the loess stratum has the most significant dewatering settlement. The proportion of settlement due to dewatering of the station construction in the loess stratum is nearly 1/3 versus the total land subsidence.

Three-Dimensional Numerical Modeling of Artificially Freezing Ground in Metro Station Construction

In this study, the engineering background of No. 2 complex connecting passage of Binhu Road Station/Jinhu Square Station of Nanning Metro Line 3 is investigated, where the artificial ground freezing technique is adopted. A three-dimensional finite element model is established to investigate the temperature development of the frozen soil curtain, with a simulation of the dynamic evolution of the frosted soil curtain. The finite element model is validated by comparing the overall trend of the measured temperature value and the resulting temperature value, which are roughly the same. According to the design scheme, the weakest part of the whole frozen soil curtain is the top of the bell mouth where the downhole tunnel intersects the connecting passage. It is recommended to make a row of smaller freezing holes to enhance the freezing effect in this area. The thickness of the frozen soil curtain reached 1.75 m or more, indicating that the whole frozen soil curtain meets the design requirements and shows the right features for excavation construction. After freezing for 40 days, the average thickness of the frozen soil curtain is 2.4 m, indicating that the freezing effect meets the design requirements. The project can be successfully carried out, which suggests that the underneath passage construction is feasible. As a result, the results of the numerical model are applicable for comparable projects using artificially freezing ground in metro station construction.

Research on Evaluation of Eco-Metro Station Levels Based on Hierarchical Analysis Models

With the help of hierarchical analysis and fuzzy comprehensive evaluation theory, this paper innovatively constructs a hierarchical evaluation model of underground metro station ecological building projects from six aspects, namely, land saving, material saving, indoor environment, water saving, energy saving and operation management, and combines with the premise of spatial specificity and complexity of underground metro stations, so as to provide a theoretical basis for the development of ecological buildings in the construction of underground metro stations. The article selects the ecological building of underground station in Qingdao, China to carry out comprehensive evaluation and validation. The results of the study show that the evaluation model based on hierarchical analysis can effectively quantify the ecological grades of metro station projects.

Study on the geological adaptability of the arch cover method for shallow-buried large-span metro stations

As a newly proposed construction method, the arch cover method (ACM) has been applied in the construction of shallow-buried large-span metro stations, but the geological adaptability of this method remains unclear. To address this issue, the main construction process and support scheme were first described based on an actual project. The potential failure mechanism was analyzed, and a numerical model was established to examine construction safety under different conditions. Geological adaptability zones for the ACM were further proposed according to various indices of safe construction. To expand the application scenarios of this method, countermeasures were established and verified by engineering practice. Four potential risks were found during ACM employment: tunnel face instability, excessive stress and cracks in the arch cover, large deformation of the arch cover, and arch cover instability or collapse. The geological adaptability zones could be divided into applicable area, cautious area and forbidden area considering the consequences of different construction risks. Without advanced reinforcement measures, this method is not recommended when the rock mass is of Grade V or lower and should be carefully employed when the rock mass is of Grade IV or the rock mass exhibits the upper soft and lower hard state. Regarding Grade V rock masses, pipe roof should be installed to provide advanced support at the tunnel face, and the arch foot should be reinforced with steel pipe piles and prestressed anchor cables. Single-layer primary support could be used to avoid project progress delay and material waste when the rock mass is of Grade III or higher.

Восприятие речи в цифровом контенте: сетевые конфликты в городских проектах

The article presents the results of the analysis on perception by network actors implementation of urban projects that affect the environment. An algorithm for adapting linguistic, psycholinguistic and sociolinguistic methods for interpreting Big Data in real time is proposed. The study has enabled identifying several conflict situation markers and rating social tension compilation. The transdisciplinary approach has been applied with the use of neural network technologies, text analysis, analysis of word associations, content analysis, sentiment analysis. The material for the study was the data of social networks, microblogs, blogs, instant messengers, video hosting, video materials, forums and reviews on the construction of metro stations in Moscow. Analysis of the data showed the ambivalent attitude of Muscovites to the construction of new metro facilities. A positive reaction, due to the need to develop the transport structure of the city, improve the transport situation, is confronted with the protest of residents who put forward a number of claims. Verbal data examination has made it possible to reveal the rating of social tension around new metro facilities. The selection and analysis of the semantic and associative network with the use of neural network technologies contributed to clarifying and expanding the linguistic paradigm in speech perception of digital content. The results of the study can be used in both text and network analysis.

Numerical Study on Stratigraphic and Structural Deformation Patterns Considering Surface Load with Pile-Beam-Arch Method Construction

Due to soil disturbance during the construction of metro stations, the initial stress of the stratum is modified, leading to ground settlement within a particular range, fracturing the surrounding buildings and even causing significant ground deformation and building collapse. This paper employed the Pile-Beam-Arch method to assemble the Daguanying Station of Beijing Metro Line 7 as the engineering background. The numerical calculation method was used to study the regulations of ground settlement and structural deformation throughout the construction stage. Meanwhile, the effect of surface loading was taken into account and surface settlement control strategies were suggested. Finally, the Stochastic medium theory was used to predict surface settlement. It was evident from the study’s findings that the pilot tunnels excavation and the arches installation accounted for 67% and 23.1% of the total surface settlement, respectively, and produced the most surface settlement. Surface settlement can be significantly reduced by utilizing grouting reinforcement technology and the pilot tunnels excavation approach of “upper first, then lower and side first, then middle”. The structure was much less stressed during the pre-construction stage, with the maximum principal stress ranging from 1 to 5 MPa; after construction was finalized, the maximum principal stress reached 14.203 MPa, concentrating mostly in the middle column part, which was the consequence of the combined action of the upper load and the lower soil uplift. Additionally, there was a linear relationship between the surface load and ground settlement. The bottom slab and the middle column were situated where the structure’s most unfavorable components were concentrated. The conclusions of the surface settlement prediction demonstrated that there were discrepancies between the theoretical calculation and the simulated; thus, the prediction results were more conservative. The study results can serve as a reference for construction sites.

A new construction method for metro stations in dense urban areas in Shanghai soft ground: Open-cut shafts combined with quasi-rectangular jacking boxes

At present, the metro station constructions in dense urban areas face significant challenges during the rapid urban metro network expansion. The repeating disturbances to city traffic, commerce, and residents' daily life induced by conventional open-cut metro station constructions can no longer be accepted in dense urban areas. To solve these problems, some underground excavation methods, such as enlarging shield tunnels, shallow tunnelling method and pipe-roof mining method, have been attempted, but it is difficult for them to be adapted to the strict limitation of urban space in soft ground. In this paper, the planning, construction, challenges, and relevant key techniques of an innovative type of metro station – open-cut shafts combined with quasi-rectangular jacking boxes (SCJB) were introduced and investigated. The main conclusions are as follows: (1) For the advantages of efficient underground space utilization and little impact on traffic and environment, the SCJB method is recommended for the constructions of metro stations that need to traverse the heavy traffic roads and express-way viaducts. The flexible combinations of open-cut shafts and jacking boxes can form various layouts of underground space to adapt to various complex surrounding environment. (2) Steel-concrete composite lining was designed for jacking boxes considering the transportation convenience and bearing capacity enhancement, and the corresponding earth pressure balanced box jacking machines were developed. (3) By applying thick thixotropic slurry with small filtration loss, the jacking resistance of the large-section box culverts was effectively reduced to 4–6 kPa and the total jacking force was kept at 30,000 kN. (4) By surveying with laser guiding system and performing timely rectifications, the trajectory deviations induced by two large adjacent box jacking were controlled within ±50 mm. The horizontal convergence of east line box segments caused by the west line jacking was controlled within 1.5 mm, through strict trajectory control. The surface settlement induced by the crossing of three box jacking tunnels was effectively controlled within 15 mm. The experiences learnt from this project can provide valuable references for the planning and construction of metro stations in dense urban areas in soft ground.

Внутригородское железнодорожное сообщение в «ядре» агломерации

Purpose: To develop a proposal to increase the attractiveness of railway transport by launching an intra-city route in municipalities where the construction of metro stations is not expected in the next decade. Analysis of the settlement of agglomeration and zones of gravity to agglomeration “core”. Analysis of the existing railway transport infrastructure. Analysis of suburban traffic in the Vitebsk direction. Identification of the problems of uneven development of transport infrastructure in the St. Petersburg agglomeration and adjacent territories, the problem of congestion of urban infrastructure in the conditions of rapid development of residential building of territories and the lag in infrastructure development. Analysis of possible passenger traffic on the route of intra-city railway connection Kupchino-Rzhevka-Devyatkino. Methods: Statistical research, analysis and synthesis, the method of polygon approach. Results: The project passenger turnover in the direction of Kupchino — Rzhevka — Devyatkino was determined. The route of a new urban communication with high capacity in areas with a poorly developed transport system and promising areas for housing construction is proposed, the route also connects southern, eastern and northern areas of the agglomeration. Practical importance: The development of intra-city communication routes with small traffic intervals, providing an attractiveness of more ecological transport compared to automobile one, with such traffic that’s independent of situation on street road network.

Численное моделирование геомеханических процессов при строительстве перегонных тоннелей Московского метрополитена

The largest megalopolis and the main business center of the country, the city of Moscow, is actively expanding from year to year. In this context, the Russian capital is faced with the challenge of developing and expanding its transport infrastructure. According to the 2021 construction plan of the Moscow Metro the total length of the lines will exceed 450 km, and the Big Circle Line will become one of the longest in the world. During the construction of new metro stations specialists face difficult engineering, geological and hydrogeological conditions. Reducing the risks and preventing accidents during underground construction is relying on accounting of all the levels of the excavation and construction works. The article presents a comprehensive analysis of the factors that affect the choice and justification of underground construction technologies. The paper presents the objectives of geomechanical monitoring and measures for geomechanical safety of excavations. Numerical modeling of geomechanical processes during the construction of the running tunnels was made using the Map3D Software. The simulation considered a tunnel of circular cross-section passing through a non-uniform rock mass. The diameter of the cross-section was accepted to be 6 m with the depth of the driving tunnel varying from 15 to 35 m.

Comparison of the Spreading Characters of Fire Products in the Typical Metro Stations of Washington, D.C., and Guangzhou

Fire is one of the most common disasters that threaten the safety of the crowd in metro stations. Due to the variations in the design of metro stations, the hazard posed by the spreading products of the fire can pose different risks. The typical structures of metro stations in Guangzhou and Washington, D.C., are very different from each other. In Washington, D.C., the “high-dome” structure is predominant in the construction of metro stations, while in Guangzhou, most metro stations have the “flat ceiling” structure. In this article, a numerical modeling for fire dynamic simulation is used to predict and compare the spreading characters of fire products (the smoke height change, the temperature distribution and the visibility change) when fires with 2.5 MW heat release rate occur in the platform center and at the platform end in the two kinds of metro stations. The results show that, in the same fire scenario, the lowest smoke heights monitored in the Guangzhou model is 0.6 m (fire at the platform end) and 0.8 m (fire in the platform center) above the safe smoke height in 360 s after a fire breaks out, while it is 6.15 m (fire in the platform center) and 6.2 m (fire at the platform end) above the smoke height in the Washington model. The temperature increment in the Guangzhou model is 23 °C (fire in the platform center) to 29 °C (fire at the platform end) in 360 s after the fire breaks out, while the temperature increment in the same period in the Washington model is 8.5 °C (fire at the platform end) to 9 °C (fire in the platform center). The visibility of most areas on the platform of the Guangzhou model is about 1 m no matter the fire is in the platform center or at the platform end at 360 s after the fire begins, while in the Washington model, the visibility of most areas is 1.5–13.5 mm (fire at the platform end) to 4–14 m (fire in the platform center) at the same moment. Based on the results, the environment is worse when the fire happens at the end of the platform than that when the fire happens in the platform center of the Guangzhou model. While the fire location has fewer impacts on the smoke height, temperature, and visibility in the Washington model, metro stations with a high-dome structure can be beneficial to fire evacuation safety; however, the construction cost can be high. Metro stations with flat ceiling are widely used in more cities for it has lower construction cost; to compensate for its weaker abilities under fire conditions, it is suggested that smoke exhaust systems should be carefully and fully considered.

Uncertainty analysis and visualization of geological subsurface and its application in metro station construction

Uncertainty analysis and visualization of geological subsurface and its application in metro station construction