Underground Metro Station 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

Optimization Study on Key Technology of Improved Arch Cover Method Construction for Underground Metro Stations Based on Similar Model Test

To enhance comprehension of the improved arch cover construction method for underground metro stations and provide guidance for future construction techniques and programs, the paper examines the indoor improved arch cover method of construction in the underground concealed excavation station of Tianhe Road Station of Guangzhou Metro Line 10, China. It includes a similar model test of the key technology and an analysis of the evolution law of the surrounding rock stress, the law of the ground settlement, and the law of the arch top deformation after the tunnel excavation. The study found that increased over-support can decrease arch settlement, with the maximum settlement occurring near the arch. Ground settlement typically occurs in the same areas as arch settlement, but arch settlement may occur earlier. The excavation of the arch cover has little impact on the overlying soil pressure, and the supporting structure is more effective in controlling soil deformation. The upper part of the arch cap experiences mainly extrusion stress, with the maximum stress occurring near the middle of the arch. The stresses in the arch’s base decrease significantly during the excavation of the side drifts but show an increasing trend during the excavation of the lower rock mass. The presence of the central column significantly affects both the settlement of the arch and the ground, as it bears most of the compressive stress of the arch. This stress decreases initially and then increases. The amplitude of deformation is more pronounced when the dismantled central column is closer to the middle of the arch.

Investigating the influence of outdoor temperature variations on fire-induced smoke behavior in an atrium-type underground metro station using hybrid ventilation systems

Underground metro systems are expanding rapidly worldwide, necessitating research on energy-efficient ventilation systems, fire safety, and smoke control. This study investigates the optimisation of hybrid mechanical-natural ventilation for smoke control in complex metro stations. Full-scale winter/summer experiments and numerical simulations examined a double-deck atrium-type station. Results demonstrate the atrium fires are more significantly impacted by outdoor temperature variations versus concourse/platform fires, with a 70 K versus 30 K temperature rise above the fire respectively. The heat of the gathered high-temperature smoke inside the atrium can reach up to 900 K under a 5 MW train fire energy release. The dimensionless Archimedes number (Ar) defines the ratio of thermal buoyancy to gravitational forces. Cold exterior winter air (Ar<1) entering via the atrium ceiling openings restricted vertical smoke diffusion, enabling enhanced lateral propagation. With rising outdoor temperatures from −20 °C to 10 °C (Ar<1), the natural smoke extraction efficiency increased from 0 to 18 %, coupled with vertical airflow velocities accelerating from −3.5 m/s to 1.5 m/s. When outdoor temperatures were between 10 °C and 40 °C (Ar>1), airflow velocity only changed slightly. Empirical models predict internal temperature profiles as a function of external meteorology. The findings provide crucial engineering insights into integrating weather data and adaptable ventilation protocols for scenario-based smoke prevention/mitigation. Further work should examine seasonal variations beyond the tested -20‒40 °C range. Overall, considering outdoor climate effects allows 30 % optimisation of hybrid ventilation systems for fire safety in underground metro stations. This study promotes technological advances in energy-efficient transport infrastructure resilience.

Seismic soil pressures on underground metro station in soft soil: Experimental studies and analytical comparisons

The seismic design of metro stations relies on the accurate assessment of the magnitude and distribution of seismic soil pressures. Seismic soil pressure (SSP) is an important load acting on the side walls of metro stations and its magnitude and distribution shape have been one of the hot topics of research in the field of seismic resistance. In view of this, a shaking table test on a soil-metro station model under different seismic excitations was carried out, where SSP data were collected from the side walls and a residual was introduced to quantify the deviation of the test values from the analytical values. The results show that: (i) the difference between the absolute values of the SSPs along the left and right side walls at same burial depth and time is small, with one tension and one compression. (ii) The time history of the SSP along the side walls has periodic characteristics and first-order predominant frequency of SSP is consistent with that of the ground. (iii) The widely used analytical equations do not reflect the actual situation of the SSP along the side walls of the metro stations.

Passengers’ experience in underground non-transfer metro stations: The impact of spatial characteristics

Underground spaces have emerged as a promising solution for enhancing the overall quality of life in cities by allowing for better land use, reducing noise, and improving air quality. However, the subterranean placement of non-infrastructure facilities gives rise to numerous apprehensions, predominantly concerning the experience of their users. The underground environment may evoke fears and anxieties, disrupt cognitive and physiological responses, and affect personal safety. This paper examines the extent to which the specific spatial characteristics of underground non-transfer metro stations influence the passenger experience measured by the subjective indicators of comfort and safety. The research combines survey data collected from 1400 users with spatial data obtained from space syntax analyses and field investigations of 28 underground metro stations in Warsaw, Poland. Based on the results of multiple regression analysis, a set of spatial features that affect user comfort and safety was identified. The results show that passengers’ experience is shaped by several architectural characteristics of metro ‘stations, as well as their accessibility and position in the city and neighbourhood. Among the most influential architectural features is the configuration of the concourse level followed by the geometry of the platform hall and the use of art elements. Based on the findings presented in the study, potential design strategies that could improve the user experience are proposed and discussed. The recommended approaches offer valuable insights for designers aiming to improve the existing metro stations and facilitate more effective designs for new underground facilities.

A comprehensive review of seismic response of cast-in-place and prefabricated underground metro station buildings

A comprehensive review of seismic response of cast-in-place and prefabricated underground metro station buildings

Occupational exposure and personal exposure to hazardous air pollutants in underground metro stations and factors causing poor indoor air quality

Occupational exposure and personal exposure to hazardous air pollutants in underground metro stations and factors causing poor indoor air quality

Dynamic analysis on the structure of metro station under high-speed railway load

High-speed railways often run over underground metro stations. Dynamic load induced by high-speed train can influence the internal force of underground structure and hence can pose danger to the underground structure. Hence, it is necessary to estimate the safety of underground structure due to high-speed train load. In this paper, the effects of dynamic load induced by high-speed train on metro station are investigated by carrying out three-dimensional numerical analysis. Guinan high-speed railway, which is designed to run over Jinqiao metro station in Nanning, Guangxi province of China are adopted as the background of this case study. The hardening soil model with small-strain stiffness was adopted to model the behaviour of soil. Two typical speed of railway train (i.e., 160 km/h and 350 km/h) are considered in this study. Based on the numerical analysis, vertical vibration acceleration and bending moment of the structure of the metro station are presented and analysed.

Performance of Flowable Concrete for Application in Underground Structures -NATM Tunnel and Station Box of Mumbai Metro Project

Abstract: High-performance flowable concrete offers special combinations of performance, uniformity, and consistency requirements that cannot be possible by traditional normal slump concrete. It is an advanced concrete than traditional concrete with high workability without segregation, bleeding and it is suitable for placing in structures with congested reinforcement of structure, long distance pumping concrete-like inside NATM tunnel, cross passages, and underground station box concrete structures. Flowable concrete can be flow itself but does not have the self-compacting capability. Flowable concrete required vibration to ease flow to reach each corner of formwork and compaction for achieving a smooth surface finish after deshuttering. Mix proportion of flowable concrete must ensure a good balance between deformability and stability. The behavior of concrete can be affected by the characteristics of selected ingredients in concrete and the mix proportions. It becomes necessary to evolve a procedure for mix design of flowable concrete. The paper presents an experimental procedure for the mix design of flowable concrete for grade M40 and implementation of the same mix at the cast in situ Base slab, Roof slab Rcc walls for underground metro stations, NATM tunnel &amp; cross passages in Mumbai Metro Project, package -UGC-07. The test results for acceptance characteristics of M40 grade flowable concrete such as flow table test, compressive strength at the ages of 7, 28, and 56 days determined, and results are included here. Successful production of temperature control flowable concrete from batching plant, transportation, placement procedures, and proper planning of handling and execution of flowable concrete at the site are presented in this article.

Indoor Air Quality Assessment of Metro Stations Based on the Optimal Combination Weight and Improved Fuzzy Comprehensive Evaluation

Aair quality issues and respiratory diseases have become issues of particular concern since the outbreak of the COVID-19 pandemic. The indoor air quality of crowded places such as underground metro stations has received growing attention from passengers and staff, thus requiring both qualitative and quantitative assessment. However, the traditional fuzzy comprehensive evaluation is ineffective in this respect. Therefore, this paper proposed the method of optimal combination weight and improved fuzzy comprehensive evaluation to assess the air quality. First, subjective weights were calculated with the multiple-input weighted precedence chart and analytic hierarchy process; objective weights were computed using the entropy weight and exceedance multiple methods. Second, the moment estimation theory was introduced for the optimal combination of these weights. Results show that the optimal combination weighting method achieves the minimum relative deviation. Moreover, in the traditional fuzzy comprehensive evaluation, the air quality is generally classified based on the maximum membership, and the evaluation is inapplicable when the validity (K0) is less than 0.5. Therefore, the concept of confidence was introduced herein for improvement. Finally, the optimal combination weight and improved fuzzy comprehensive evaluation is proved to be the most reasonable in comparison with the traditional fuzzy comprehensive evaluation and indoor air quality index. This study not only suggests a good method to assess the indoor air quality of metro stations but also provides references for decision makers.

Uncertainty method and sensitivity analysis for assessment of energy consumption of underground metro station

An accurate calculation of energy consumption is a precondition for energy underground metro station design, which determines the amount of energy geostructure. This study develops a simplified deterministic method for the underground metro station energy performance that accounts for weather and interior heat gain uncertainty. A Monte Carlo technique with Latin hypercube sampling is then employed to confirm the probability distributions of the peak load, average yearly load and annual energy demand, and compared to deterministic method to improve the design robustness. The sensitivities of 14 input variables with respect to the underground metro station energy performance are discussed through three sensitivity methods. The simplified deterministic method is more accurate than the DeST and American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) in describing the fluctuation of the underground metro station energy performance. The uncertainty distribution of energy performance is advantageous to the system design, considering both safety and economy. Moreover, a comparison with the deterministic method is performed to determine the reasonability of the safety factor 1.2, which is usually used in practical programs. The peak load is dominated by outdoor parameters, while there are no control parameters for the average yearly load or annual energy demand.

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.

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.

Improving the special motor qualities of experienced female volleyball players living on the territory of martial law

Background and purpose. The training of athletes in conditions of limited freedoms (COVID-19 pandemic and martial law in the territory of residence) does not allow for the full training of athletes in team sports. The purpose of the study is to determine the organizational forms and means of training sessions aimed at improving special physical qualities under martial law. Material and methods. The study involved experienced volleyball players of one team (n=12). Volleyball players live in the territory of martial law (Kharkiv, Ukraine) and the restrictive measures of the COVID-19 pandemic. The experiment was carried out for 6 months in 2022 during martial law in Ukraine. The organization of the training was carried out with an emphasis on independent individual work. Pedagogical testing was carried out. 5 test exercises were used: each volleyball player performed independently. Volleyball players are offered an individual training plan that takes into account: safe living conditions (presence of special shelters – underground metro stations near the place of residence, special shelters, basements of houses, etc.); availability of electricity and means of communication (mobile, Internet); availability of means of life support (drinking water, food). Results. It was determined that the team is homogeneous only in the test exercise “long jump from a place”. The indicators of the other four tests indicate the heterogeneity of the group of volleyball players. The use of the ZOOM videoconference to monitor the performance of tests by volleyball players under martial law has been substantiated. Conclusions/ Exercises for the development of certain physical qualities of volleyball players are proposed. Also, schemes of remote self-training are proposed to level the heterogeneity of the group.

Seismic fragility analysis of a two bay two storey underground metro station: a case study

Seismic fragility analysis of a two bay two storey underground metro station: a case study

Field measurement of microclimate of sunken square and its effect on indoor environment of underground metro station in subtropical region

Because of the needs of rail transit and urban construction, metro stations have various forms of entrances. In particular, in recent years, the sunken square has been increasingly designed and applied to underground transportation hub systems. Because the sunken square is directly connected to the indoor environment through the entrances, the microclimate of the sunken square can directly affect the indoor environment. When air enters the underground transportation hub through the entrance, it has a nonnegligible impact on indoor thermal comfort and energy consumption. In this study, two representative metro stations with sunken squares in Shenzhen, China, which is a typical metropolis in a subtropical region, were selected. The microclimates of the sunken squares were investigated, the air flow rates through the entrances were measured, and the indoor environments of the two stations were studied. The test results show that the attenuation effect of wind increases with the shape coefficient of the sunken squares. In addition, the temperature gradually increases from the bottom to the top of the sunken square. The neutral physiological equivalent temperature (PET) in the sunken squares was 29 and 19 °C in summer and winter, respectively. Meanwhile, the air flow rate through the sunken square entrances was relatively large, and the influence factor was obtained. The results of the systematic measurements provide a data basis and technical guidance for the design of sunken squares and metro stations, and can help improve the quality of the indoor environment in such underground metro stations.

Deep-AI soft sensor for sustainable health risk monitoring and control of fine particulate matter at sensor devoid underground spaces: A zero-shot transfer learning approach

Underground building spaces such as metro stations have been widely adopted in densely populated metropolitan cities to combat high traffic congestion. To ensure a sustainable underground environment, early warning systems, primarily for fine particulate matter, and ventilation control, are of great significance. However, these techniques require substantial sensor data, which is generally not accessible in real-life situations. This work presents a solution to sensor data unavailability at underground metro stations by integrating a sequence forecasting soft-sensor framework with zero-shot transfer learning (ZSTL). The proposed data-driven soft-sensor model consists of a multi-head attention aware bi-directional gated recurrent unit (MH-BiGRU) that forecasts the PM2.5 one hour ahead of time to provide an early health risk warning and proactive ventilation operation. The results suggest that the forecasts by the proposed model outperform stacked long short-term memory and gated recurrent unit structures by 17% and 20%, respectively. Whereas 72% of the residual errors by MH-BiGRU were situated between −5 to 5 CIAI units. Additionally, the proposed ZSTL framework reduced the zero-shot prediction error by 75%, 17%, and 82% at three target metro stations, where the data of target sensor PM2.5 was not available. The ventilation control by forecasted PM2.5 levels can decrease indoor PM2.5 concentrations by 25% and has the potential to reduce energy demand by 18%, enabling sustainable operation.

Evaluating new evacuation systems related to human behaviour using a situational awareness approach – A study of the implementation of evacuation elevators in an underground facility

Elevator evacuation is associated with several safety benefits and can be a cost-efficient evacuation strategy in many buildings or facilities. Despite the advantages, elevator evacuation is not yet a common strategy in the built environment. In this paper, a design strategy that allows the designer to consider information needs of evacuees when designing the information and guidance measures for evacuation elevators is presented. The strategy is based on human behaviour theories and the Theory of Affordance. The use of the design strategy is also illustrated for a case study, i.e., an underground metro station with evacuation elevators. This case study identifies several important measures, which accommodate the information needs of the evacuees, e.g., (1) voice alarm containing information that elevators can be used for evacuation, and (2) a system in the elevator lobby indicating that the elevators are operational. The paper also highlights future research areas where the current level of knowledge related to elevator evacuation needs to increase.

The effect of ventilation system with and without under-platform exhaust on the concentration of braking micro-particles inside the subway system

Thermal comfort has been the main target of the ventilation in subway systems. However, pollutant concentration and aerosol dispersion could be the leading health issues in underground metro stations. This study numerically simulated a train movement inside a subway system using the Dynamic Mesh Technique for a 3-D computational domain consisting of four stations and connecting tunnels. The effects of both the ventilation system and the train-induced fluid flow inside the subway system were investigated. Then, the particle generation and dispersion due to train braking are considered, and the impact of the ventilation system on reducing the particle concentration inside the station was investigated. It is shown that the airflow inside the subway system is entirely affected by the piston effect. The airflow generated by the train movement is much higher than that generated by the operation of the ventilation system when only one train passes through the tunnel. The results show that the ventilation system, consisting of the supply and exhaust fans inside the tunnel and supply grilles inside the platform, can reduce the particle concentration by half, except for the platform beside the stopped train when the train enters the station and during half of the train stop time. The other design concept demonstrates that the under-platform exhaust system considerably reduces the concentration of the particles released by the train braking system on the trackside platform.

Appropriate Selection of Materials for Making Durable Self Compacting Concrete for Using in Underground Structures

Abstract: Selecting appropriate and suitable of materials plays an important role in concrete mix design to meet the general requirements of European guidelines for self-compacting concrete and to ensure a balance between deformability and stability. The type of selected materials and the ratios of concrete ingredients can be affected by the fresh and hardened properties of the concrete. In the contract agreement of the Mumbai Metro underground project, the technical specifications clearly state the values of limits set for achieving the durability parameters for the life of 120 years of the structure. According to the requirement of the site conditions Self-compacting concrete was designed with available material, special material like Ultra GGBS- Alccofine 1203 and crystalline waterproofing admixture. Self-compacting concrete is superior concrete than the traditional concrete with high workability, no segregation, no bleeding, and it is also suitable for use in structures with long-distance pumping in the instant case i.e., more than 120-meter length in Underground NATM tunnels, cross-passages, and the concrete structure of the underground metro station box. The paper presents a comparison between concrete mix designs and their achieved test parameters suitable for the contract specification of Mumbai metro underground project