Numerical Simulation of Air Distribution for Tianjin Subway Station

In rebuilding Tianjin Metro, numerical simulations are performed to evaluate the original design of the ventilation system of Southwest Station and a new system is given to optimize the velocity and temperature fields at the station. Field measurements are conducted to validate the turbulence model and acquire boundary conditions. The simulation result tallies with testing data on the sport that is found that two-equation turbulence model is acceptable in simulating complex flow at the station. A method of simplifying the simulation of the transient flow at the station into steady flow is used and the validation criterion for this simulation is also given.

Thermal comfort evaluation of people in subway station

We analyzed the characteristics of subway station environment and the change of thermal comfort for passengers when they are in and out of the station. The dynamic thermal comfort evaluation model RWI(relative warmth index) and HDR(heat deficit rate) were built on the distinguishing features of public area in subway station. Taking one representative subway station in Nanjing as the research object, the thermal comfort conditions in different seasons and different parts were studied by field tests, questionnaires and model-evaluating. The calculated RWI shows that although the thermal comfort in Nanjing metro is relatively acceptable, ideal thermal comfort has not been achieved. And it is found that associated with predicted mean vote(PMV), using RWI can evaluate the thermal comfort more precisely.

Optimization Scheme of Large Passenger Flow in Huoying Station,Line 13 of Beijing Subway System

This paper focuses on the distribution of passenger flow in Huoying Station,Line 13 of Beijing subway system.The transformation measures taken by Line 13 since operation are firstly summarized.Then the authors elaborate the facilities and equipment of this station,especially the node layout and passenger flow field.An optimization scheme is proposed to rapidly distribute the passenger flow in Huoying Station by adjusting the operation time of the escalator in the direction of Xizhimen.The authors adopt Queuing theory and Anylogic simulation software to simulate the original and the optimized schemes of Huoying Station to distribute the passenger flow.The results of the simulation indicate that the optimized scheme could effectively alleviate the traffic congestion in the hall of Huoying Station,and the pedestrian density in other places of the hall is lowered;passengers could move freely in the hall and no new congestion points would form.The rationality of the scheme is thus proved.

Numerical Simulation of Dynamic Response of an Existing Subway Station Subjected to Internal Blast Loading

In order to design and retrofit a subway station to resist an internal blast, the distribution of blast loading and its effects on structures should be investigated firstly. In this paper, the behavior of a typical subway station subjected to different internal blast Ioadings was analyzed. It briefly introduced the geometric characteristics and material constitutive model of an existing two-layer and three-span frame subway station. Then three cases of different explosive charges were consid- ered to analyze the dynamic responses of the structure. Finally, the maximum principal stress, dis- placement and velocity of the columns in the three cases were obtained and discussed. It con- cluded that the responses of the columns are sensitive to the charge of explosive and the distance from the detonation. It＇s also found that the stairs between the two layers have significant effects on the distribution of the maximum principal stress of the columns in the upper layer. The explicit dynamic nonlinear finite element software ANSYS/LS-DYNA was used in this study.

Dynamic analysis of subway station subjected to internal blast loading

The study was motivated by the fact that explosion inside the subway structure may not only cause direct life loss,but also damage the subway structure and lead to further loss of lives and properties.The propagation law of explosion wave in the subway station was analyzed and a simplified model of overpressure in the subway station was also proposed.Whereafter,the improved dynamic cam-clay model of soil and the concrete damaged plasticity constitutive model were used for the dynamic analysis of the subway station.Meanwhile,the influences of soil stiffness and burial depth on the dynamic response of the subway station were looked into.The results show that the multi-peak overpressure in the subway station does not appear,and large stresses concentrate on the central column and the floor slab of the subway station,so some special reinforcement measures should be taken in these parts.The effect of soil stiffness and burial depth on the stress of the central column is little;however,the effect on the stress of the station side wall is relatively obvious.

Seismic performance of a rectangular subway station with earth retaining system

Much effort has been made in investigating the seismic response and failure mechanism of rectangular subway stations,however,the influence of earth retaining systems has generally been ignored in previous studies.This paper presents a numerical study on the seismic performance of a rectangular subway station with/without earth retaining systems by taking fender piles as the example,and aims to illustrate how the existence of fender piles affects seismic responses on subway stations.The loading conditions of subway stations and their surrounding soils prior to earthquakes are discussed.Next,seismic responses of subway stations with or without fender piles were simulated.Afterward,earthquake-induced deformations of stations and surrounding soils,as well as the internal forces and damage modes of the structural components,were systematically studied.Consequently,the seismic performance of the stations was affected by the existence of fender piles.In addition,earthquake intensity is illustrated.The study showed that deformation modes of surrounding soils and damage modes of stations were different with regard to the existence of fender piles.Meanwhile,earthquake intensity influencing the seismic performance of stations with or without fender piles were found to be opposite.

Numerical Simulation and Field Monitoring Analysis for Deep Foundation Pit Construction of Subway Station

To investigate the effect of deep foundation pit excavation on the stability of retaining structure, a subway stationin the city of Jinan was selected as a project, and a FLAC3D-based three dimensional model was developed fornumerical simulation. The horizontal displacement of the retaining structure, the axial force of the support, andthe vertical displacement of the column were studied and compared to the collected data from the field. The findingsindicate that when the foundation pit is excavated, the maximum deformation of the retaining structure progressivelydecreases from the top, the distortion of the retaining structure gradually rises, and the final maximumdeformation is around 17 meters deep. In each layer of support, the largest axial force support is located in thefirst reinforced concrete support;the uplift of the pit bottom caused by soil unloading plays a primary role in thevertical displacement of the column, and the column exhibits an upward trend under all construction conditions.When compared to the measured data, the generated findings are comparable and the fluctuation trend is extremelyconsistent. The findings of this article may give technical direction for the development of subway stationswith a comparable engineering basis.

Seismic performance of two-story subway station structures with different isolating systems

When the sliding bearing is fixed only at the top of the middle column of the underground structure,the cracks at the side end of the middle plate should be aggravated while the seismic damage of the mid-column should be alleviated.To enhance the seismic performance of the mid-plate,a new isolation design method has been mentioned while the elastic sliding bearings are set at the top of the mid-columns and between the side end of the mid-plate and the side wall at the same time.By establishing a nonlinear finite element analysis model for the static-dynamic coupling interaction system,the seismic response characteristics of the cast-in-place station structure without a sliding bearing have been analyzed and compared with those of the station structure with the sliding bearing fixed only at the top of the middle columns,and those of the station structure with sliding bearing be fixed between the mid-plate and the sidewall at the same time.The results show that the new isolation station structures suffer fewer earthquake damages at the mid-plate and mid-columns at the same time,which can improve the overall seismic performance of the subway station structure.

Evaluation of Spatial Variability of Soil Properties in a Long-Term Experimental Tobacco Station in Southwest China

Analysis of the spatial variability of soil properties is important to arrange the experimental treatments in the experimental station. This paper aims to study the spatial structure of soil variables and their distribution in the Pengshui tobacco experiment station in Chongqing, China. Soil samples were taken from 289 soil points on 20 m grid in March 2012. Twenty-two soil chemical and physical properties were analyzed by classical statistical and geo-statistical methods. Soil pH, cation exchange capacity （CEC）, total phosphorus （TP）, available phosphorus （AP）, zinc （Zn）, magnesium （Mg） and sulphur （S） have the strong spatial dependence, with nugget/sill ratios of less than 25%. The others have the moderate dependence with nugget/sill ratios of 26.17% to 71.04%. Ranges of the spatial correlation varied from 51.30 m for chlorine （C1） to 594.90 m for TP. The clearly patchy maps of the nutrients showed the spatial distributions of the soil variables, which can be used for better management of experimental treatments, achieving reliable exoerimental results in the tobacco exnerimental station.Highlight： Scientific experimentation assumes the existence of random variability for soil attributes. This research was to evaluate the spatial variability of soil chemical and physical attributes and to interpolate the spatial distribution of soil properties in the tobacco experimental station in Chongqing. The result of this work can be used for the agricultural management of tobacco cultivation.

Functional Characteristics of Beijing Subway Stations Based on POI Data:Taking Beijing Metro Line 6 as An Example

Urban subway station is a key node related to urban social,political,economic and cultural activities.There are some differences in the location,function orientation,land use and flow characteristics of different types of stations in the city.This paper mainly used Tyson’s edge,kernel density analysis,chart analysis and other methods to classify the functional types of 412,393 POI data of 26 stations along Metro he results showed that the spatial distribution of Beijing Metro Line 6 was mainly divided into 3 categories,subway stations were divided into 4 categories.Among them,type A sites were divided into composite and single types,and the distribution characteristics of the 6 types of sites were quite different.Based on the qualitative and quantitative analysis of POI point data,this method can quickly classify and analyze the characteristics of stations along Line 6 in Beijing,which also has theoretical and practical value for the planning of urban subway lines.

Analysis of Smoke Distribution in the Subway Station with Various Main Tunnel Ventilations

Fire-driven flow analysis in the underground subway station has been performed with various main tunnel ventilations. Shin-gum-ho station （depth： 46 m） in Seoul is selected as a simulation model. The ventilation mode is assumed to be emergency state. Various main tunnel ventilations are applied to operate in a proper way for helping of smoke exhaustion in platform. The entire station is covered for simulation. Ventilation diffusers are modeled as 95 square shapes of 0.6 m × 0.6 m in the lobby and as 222 square shapes of 0.6 m × 0.6 m and four rectangular shapes of 1.2 m × 0.8 m in the platform. The total of 7.5 million grids is generated and whole domain is divided to 22 blocks for MPI （massage passing interface） efficiency of calculation. LES （large eddy simulation） is applied to solve the momentum equation. Smagorinsky model （Cs = 0.2） is used as SGS （subgrid scale） model. The distribution of CO （carbon monoxide） is calculated for various capacity of main tunnel ventilation and compared with each other.

Landscape Greening of Subway Stations Close to Commercial Districts in Beijing

Due to the rapid urban construction, commercial districts in Beijing are constructed near subway stations. Good landscape greening plays a crucial role in improving the environmental quality of the area around subway stations. At present, there are few studies on the landscape greening around subway stations adjacent to commercial districts. In this paper, field research on landscapes in the commercial district around seven typical subway stations was conducted to monitor real-time noise and crowd activities and analyze the utilization status of street parks, in order to provide a reference for the construction and renovation of the landscape greening around subway stations near commercial districts.

A practical framework for performance-based reliability analysis of subway stations based on a faultestructure combined system

It is necessary to pay particular attention to the uncertainties that exist in an engineering problem to reduce the risk of seismic damage of infrastructures against natural hazards.Moreover,certain structural performance levels should be satisfied during strong earthquakes.However,these performance levels have been only well described for aboveground structures.This study investigates the main uncertainties involved in the performance-based seismic analysis of a multi-story subway station.More than 100 pulse-like and no pulse-like ground motions have been selected.In this regard,an effective framework is presented,based on a set of nonlinear static and dynamic analyses performed by OpenSees code.The probabilistic seismic demand models for computing the free-field shear strain of soil and racking ratio of structure are proposed.These models result in less variability compared with existing relations,and make it possible to evaluate a wider range of uncertainties through reliability analysis in Rtx software using the Monte Carlo sampling method.This work is performed for three different structural performance levels(denoted as PL1ePL3).It is demonstrated that the error terms related to the magnitude and location of earthquake excitations and also the corresponding attenuation relationships have been the most important parameters.Therefore,using a faultestructure model would be inevitable for the reliability analysis of subway stations.It is found that the higher performance level(i.e.PL3)has more sensitivity to random variables than the others.In this condition,the pulse-like ground motions have a major contribution to the vulnerability of subway stations.

Numerical Simulation of Dynamic Response of an Existing Subway Station Subjected to Internal Blast Loading

In order to design and retrofit a subway station to resist an internal blast, the distribution of blast loading and its effects on structures should be investigated firstly. In this paper, the behav-ior of a typical subway station subjected to different internal blast loadings was analyzed. It briefly introduced the geometric characteristics and material constitutive model of an existing two-layer and three-span frame subway station. Then three cases of different explosive charges were consid-ered to analyze the dynamic responses of the structure. Finally, the maximum principal stress, dis-placement and velocity of the columns in the three cases were obtained and discussed. It con-cluded that the responses of the columns are sensitive to the charge of explosive and the distance from the detonation. It’s also found that the stairs between the two layers have significant effects on the distribution of the maximum principal stress of the columns in the upper layer. The explicit dynamic nonlinear finite element software——ANSYS/LS-DYNA was used in this study.

Seasonal Distribution of Manganese in the Soil-Water-Plant in the Zone of Burshtyn Thermal Power Station

This study deals with the impact of Burshtyn thermal power station on the amount of manganese in soil, water and celandine tissue. The research of manganese amount and form in the system： water-plant is of great importance due to active influence of thermal power station on the chemical structure of the polluted area. The changes in the amount and form of manganese in soil, water and plant are interrelated and depend on the season, the distance from the polluter and morph-functional plant structure, the cleaning system possibilities of the industrial enterprise and some meteorological factors.

Passengers gathering-scattering analysis at the corners of subway stations

During both daily operation and emergency evacuation,the corners of walking facilities in subway stations play an important role in efficient circulation.However,the effectiveness of the corner is difficult to assess.In this paper,a method of passenger gathering and scattering analysis based on queueing models was proposed to investigate the corner performance in subway stations.Firstly,we constructed a set of state spaces of passenger flow according to passenger density and proposed the state transition model of passenger flow.Moreover,the model of passenger flow blocking and unblocking probability were also presented.Then,to illustrate the validity of the method and model,several passenger gathering-scattering scenarios and were simulated to verify the influence of passenger distribution and facility width on passenger walking,and the blocking probability,throughput,and expected time were also analyzed under various widths of the target corridor and arrival rates.Results showed that the proposed model can reproduce the trend of walking parameters changing and the self-organizing phenomenon of'faster is lower'.With the increase of arrival rates of passengers,walking speeds of passengers decrease and the expected walking time is prolonged,and the blocking probability sharply increased when the arrival rate exceeded 7 peds/s.In addition,with change of width of the target facility,efficiency of capacity of walking circulation facility fluctuated.With the width of the target corridor enlarged by 10%,the steady state of passenger flow was less crowded.Therefore,corridor width is critical to the circulation efficiency of passengers in subway stations.The conclusions will help to develop reasonable passenger flow control plans to ease the jam and keep passengers walking safely.

Calculation of CO Behavior in the Platform for Deeply Underground Subway Station with Different Fire Strengths

Effect of different fire strengths on the smoke distribution in the subway station is investigated. Shin-Gum-Ho station （line #5） in Seoui is selected as a case study for variation of CO （carbon monoxide） distribution caused by the fire in the platform. The ventilation in the station is set to be an air supply mod in the lobby and an air exhaustion mod in the platform. One-side main tunnel ventilation （7,000 m3/min） is applied to operate in the tunnel. The fire is assumed to break out in the middle of train parked in the platform tunnel. Two kinds of fire strength are used. One is 10 MW and the other is 20 MW. Ventilation diffusers in the station are modeled as 317 square shapes ＆ four rectangular shapes in the lobby and platform. The total of 7.5 million grids is generated and whole domain is divided to 22 blocks for parallel computation. Large eddy simulation method is applied to solve the momentum equation. The behavior of CO is calculated according to different fire strengths and compared with each other.

Study on the Principle Model and Simplification of Subway Station Itemized Energy Consumption

Owing to the constant modernization and urbanization of China,most cities have subways,and the total power consumption of subway stations has been rising,which contradicts with China’s green goals.In this regard,energy consumption indicators for major energy use projects in subway stations should be established,comprehensive evaluation and detailed research on the current situation of subway operation should be conducted,and specific energy-saving measures should be taken from a diversified perspective.It is crucial to systematically sort out the principle of sub-item energy consumption in subway stations,and practice and explore the specific simplification measures of the principle model of sub-item energy consumption,so as to lay a solid foundation for achieving the goal of reducing energy consumption of subway stations.

Changes in sediment discharge in a sediment-rich region of the Yellow River from 1955 to 2010: implications for further soil erosion control

The well-documented decrease in the discharge of sediment into the Yellow River has attracted considerable attention in recent years. The present study analyzed the spatial and temporal variation of sediment yield based on data from 46 hydrological stations in the sediment-rich region of the Yellow River from 1955 to 2010. The results showed that since 1970 sediment yield in the region has clearly decreased at different rates in the 45 sub-areas controlled by hydrological stations. The decrease in sediment yield was closely related to the intensity and extent of soil erosion control measures and rainstorms that occurred in different periods and sub-areas. The average sediment delivery modulus（SDM） in the study area decreased from 7,767.4 t/（km^2·a） in 1951–1969 to 980.5 t/（km^2·a） in 2000–2010. Our study suggested that 65.5% of the study area with the SDM below 1,000 t/（km^2·a） is still necessary to control soil deterioration caused by erosion, and soil erosion control measures should be further strengthened in the areas with the SDM above 1,000 t/（km^2·a）.

Collapse of a Deep Excavated Foundation Pit in the Soft Soils by 3-D FEM

In view of the collapse of a deep excavated foundation pit of the Xianghu subway underground station in Hangzhou of China,the main features of the accident are analyzed,and the induced factors of the accident are summarized. Then,a 3-D FEM analysis model is created to demonstrate the soil-support structures interaction system,and the effect of the main factors,such as the volume replacement ratio of the bottom soil reinforcing,the asymmetric ground overload,the embedded depth of the diaphragm wall,the shear strength of the bottom soils disturbed by the construction,and the excessive excavation of the bottom soil,are analyzed and compared. The results show that the ineffective original reinforcement plan for the bottom soft soil is the most prominent factor for the accident,and the disturbance effect of the deep excavation on the shear strength of the bottom soft soil is another significant factor for the accident. Meanwhile,if the reinforcement of the bottom soft soil is canceled,an appropriate extension of the diaphragm retaining walls to the under lying harder soil layer can also effectively prevent the collapse of the deep excavated foundation pit. In addition,the partly excessive excavation in the process has a great influence on the axial force of the most nearby horizontal support but few effect on the stability of the diaphragm wall. Thus,the excessive excavation of the bottom soils should not be the direct inducing factor for the accident. To the asymmetric ground overload,it should be the main factor inducing the different damage conditions of the diaphragm walls on different sides. According to the numerical modeling and actual engineering accident condition,the development process of the accident is also identified.