• Fire Science and Engineering
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• v.26 no.3
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• pp.1-7
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• 2012

When the subway car stop on track, passengers have to overcome a height of 1.2 m from floor level of the subway car to the level of track for evacuation. In this experiments, participates in the group of twenties or under ages were rapidly jumping down from the subway car. However, Most elderly group were not easy to overcome the height without help of others and some of them were fell and injured. In case of merging flows, the flow rate of the group of twenties was lower than the other cases. If fire occurred in the train and train stopped in the tunnel, it will be needed a lot of total evacuation time because of the heigh difference and wall effect from subway car to outside.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.46-55
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• 2006

There are many kinds of braced cut wall methods as the sheet pile, SCW, CIP and slurry wall which is adoptable for a deep excavation construction in a coastal filled land. The braced cut wall which has a strong stiffness is very stable but it has the weak point that the construction cost is high. Thus when a braced cut wall is designed, the geotechnical engineers choose the braced cut wall which has more safe and economic in the consideration of surrounding buildings near the construction site. Especially, when the sheet pile method as a braced cut wall is cheesed, the layer order and consistence of a coastal deposit stratum are considered and the pile driving method is also considered. This paper introduces the case that the originally box-type sheet pile wall was changed to U-type and high strength material after the pilot test at the subway construction site in a coastal filled land. This paper also introduces the case that the sheet pile's driving method was changed to special method in the section of the temporary coffer dam which had made when the present coastal filled land was formed.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.598-602
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• 2006

Local scour is associate with particular local types of vortex around bridge piers. This paper is method of protection local scour for the existing Busan City subway 3 Line bridge piers and Gupo large bridge piers. In order to take design of protection of local scour this bridge piers, We calculate the local scour hole of depth , scour width, riprap construction , filter construction by formulas. We had experimental hydraulic model test for this bridge piers in order to take proof for the calculation of local scour. We knew that the vortex intensifies the local flow velocities and acts to erode sediment from the scour hole and transport it downstream. As the result of hydraulic model test, we could suggest three types method of protection local scour this bridges. We knew that FHWA HEC-18(Richardson et al. 2001: Modified CSU) Formula is useful to checking calculation as application of field. One is pier protection using the sheet piles and riprap, the others are pier protection using the riprap with filter and to make renew Wall-caisson. The best method of protection for the existing Busan City subway 3 Line bridge piers and Gupo large bridge piers is pier protection using the sheet piles and riprap.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.312-318
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• 2004

The wall in a subway structure is easily subject to crack occurrence since its expansion and shrinkage associated with hydration heat reaction is constrained by the slab. The greater problem is that the crack in the wall may be developed to pass through thickness and eventually deteriorate the structure due to rusting of reinforced steel. Thus, this study aims at controlling thermal cracks as much as possible and determining an optimized size of concrete placement through hydration heat analysis. For this study, effects of placement height, length, temperature and types of cement on the thermal cracks were evaluated by temperature rise, thermal stress and crack index. As results of parametric study, it was found that placement height and length do not have an effect on the temperature rise but have significant one on thermal stress which relates to direct possibility of thermal crack occurrence. This means that proper selection of size balancing internal constraint with external one is much more important than reducing the placement height and length simply. In order to prevent from thermal cracks most effectively, in addition, it was noted to reduce placement temperature and to use the cement blended with mineral admixture.

• Journal of the Korean Professional Engineers Association
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• v.17 no.3
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• pp.32-49
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• 1984

The East gate station area is 205M long and 24m deep which is located 13 meter in front of cultural treasure east gate. The area to be excavated by blasting is composed of granite rocks from 10M depth to 25M. Surface earth extends to up 10M depth. This job site has in involves heavy traffic congestion such as over 10,000 cars passing in rush hour where clossing No 1 lint of subway running 3 minitues head way. This east gate station construction is to be executed for the provent of the setting down of underground level and blasting vibration effects to cultural treasure east gate. Therefore, the caltural treasure committee approved this execution subject to the following condition. 1. Subway gelogical foundation and measured natural frequency 2. Execution of water tight wall 3. Sellection and test of damping material for wall and under rail 4. Measurement of monitoring system during the execution 5. Measurement of histogram system The above two projects was carried out by Dr. Kwang team in KAIST and prof, Han in Hanyang University under accadamic study contract. In the blasting work, for the pourpose of reduced vibration and low explosion velocity such as CCR, Kovex slurry. The 2nd, used electrical caps shall be delay cap and M/S caps in multi delay. The 3rd, drilling pattern is bench cut in open cut and applied control blasting in tunnelling and also shall drill anti-vibration holes as line drilling.

• Geomechanics and Engineering
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• v.19 no.4
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• pp.315-327
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• 2019

Deep excavations for development of subway systems in metropolitan regions surrounded by adjacent buildings is an important geotechnical problem, especialy in Tabriz city, where is mostly composed of young alluvial soils and weak marly layers. This study analyzes the wall displacement and ground surface settlement due to deep excavation in the Tabriz marls using two dimensional finite element method. The excavation of the station L2-S17 was selected as a case study for the modelling. The excavation is supported by the concrete diaphragm wall and one row of steel struts. The analyses investigate the effects of wall stiffness and excavation width on the excavation-induced deformations. The geotechnical parameters were selected based on the results of field and laboratory tests. The results indicate that the wall deflection and ground surface settlement increase with increasing excavation depth and width. The change in maximum wall deflection and ground settlement with considerable increase in wall stiffness is marginal, however the lower wall stiffness produces the larger wall and ground displacements. The maximum wall deflections induced by the excavation with a width of 8.2 m are 102.3, 69.4 and 44.3 mm, respectively for flexible, medium and stiff walls. The ratio of maximum ground settlement to maximum lateral wall deflection approaches to 1 with increasing wall stiffness. It was found that the wall stiffness affects the settlement influence zone. An increase in the wall stiffness results in a decrease in the settlements, an extension in the settlement influence zones and occurrence of the maximum settlements at a larger distance from the wall. The maximum of settlement for the excavation with a width of 14.7 m occurred at 6.1, 9.1 and 24.2 m away from the wall, respectively, for flexible, medium and stiff walls.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.509-514
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• 2010

A numerical simulation of passenger evacuation in a subway station was performed by coupling the passenger flow analysis and the fire simulation. The algorithm of the passenger flow analysis was based on a DEM (Discrete Element Method) using the potential map of the direction vector for each passenger. This algorithm was improved in the present study as to use finer grid smaller than a passenger in order to resolve detailed geometry of the station and to resolve the behavior of passengers in the bottleneck at the ticket gate considering the collision of passengers to a wall or with other passengers. In the fire simulation, the CO distribution predicted by using CFD was used to take into account the effect of toxic gases on the passengers' mobility. The methodology proposed in the present study could be used in designing safer subway station in case of fire occurrence.

• Journal of the Korean Professional Engineers Association
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• v.15 no.2
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• pp.3-15
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• 1982

The study on prevention measures for vibration and excavation of tunnel for the #3, #4, Seoul Subway. In the Seoul subway tunnel blasting, the drilling pattern and prevention method to seismic vibration are as follows as well as for adaptions of NATM, the supportings of roof and wall holes are arranged with control blasting. 1. The blasting is executed basically using the low velocity explosive such as slurry, Nitrate ammonium explosive, and F-I and F-II explosive for control blasting substituting of existing dynamite. 2. The cut holes are arranged with burn cut pattern and also must be arranged with M/S electrical delay caps substituting of ordinary do]ay caps. 3. Jack leg drills are used in Five Job sites and a jumbo drill in one job site. 4. In performance of safety work and in maintenance of building safety. The drilling length for blasting will not exceed 1.20 meter for round so that the vibration value shall carry below 0.3cm/sec. The harmonizing of better powder, better drilling machine and better technique is only the way of improving tunnelling efficiency and less vibration will help the dereasing of accidence.

• Journal of Science and Technology Studies
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• v.10 no.2
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• pp.77-105
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• 2010

This essay aims to look into the possibility and limit of a technological fix with the PSD (platform screen door), which was proposed as the solution of subway risk problems. Subway risk problems may be classified into five categories-on-rail accidents, in-station accidents, platform accidents, spatial risks in underground, and risks due to a crime or terror-, and the platform accidents, which happens at the interface between the rail and the station, is the most serious and prominent. The PSD is considered as an effective technical means to prevent platform accidents. However, there remains a possibility of aggravating unexpected and invisible risks. When a fire breaks out in platforms, especially at exchange stations during the rush hour, the PSD can become a "wall of outcrying", since it may act as the "safety shutter" which killed many people in the 2003 Daegu subway disaster. This is why we need to look into the limit of a technological fix with the PSD.

• Geomechanics and Engineering
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• v.38 no.4
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• pp.381-395
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• 2024

With the wide application of urban subway tunnels, the foundation pits of new stations and existing subway tunnels are becoming increasingly close, and even zero-distance close-fitting construction has taken place. To optimize the construction support scheme, the existing tunnel's vertical displacement is theoretically analyzed using the two-stage analysis method to understand the action mechanism of the construction of zero-distance deep large foundation pits on both sides of the existing stations; a three-dimensional numerical calculation is also performed for further analysis. First, the additional stress field on the existing tunnel caused by the unloading of zero-distance foundation pits on both sides of the tunnel is derived based on the Mindlin stress solution of a semi-infinite elastic body under internal load. Then, considering the existing subway tunnel's joints, shear stiffness, and shear soil deformation effect, the tunnel is regarded as a Timoshenko beam placed on the Kerr foundation; a sixth-order differential control equation of the tunnel under the action of additional stress is subsequently established for solving the vertical displacement of the tunnel. These theoretical calculation results are then compared with the numerical simulation results and monitoring data. Finally, an optimized foundation pit support scheme is obtained considering the pit corner effect and external corner failure mode. The research shows a high consistency between the monitoring data,analytical and numerical solution, and the closer the tunnel is to the foundation pit, the more uplift deformation will occur. The internal corner of the foundation pit can restrain the deformation of the tunnel and the retaining structure, while the external corner can cause local stress concentration on the diaphragm wall. The proposed optimization scheme can effectively reduce construction costs while meeting the safety requirements of foundation pit support structures.