• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2389-2392
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• 2011

To construct a tunnel to the bottom of the existing tunnels by the behavior of the tunnel to examine the scope and effect, Schubert (1995) Influence Line and Trend Line to the proposed concept was introduced. Crossing angle of the existing tunnels and new tunnels 15, 30, 60, and 90 were set, the lower ground after 3-grade fixed above the ground was graded a 3-grade and 5-grade. Interpreted as a result of these conditions, the tunnel diameter 10m (D) If the crossing angle of around 90 degrees, 60 degrees, 30 degrees or less, each 3.0D, 3.5D, 4.0D, respectively, in the range of the effect could be estimated.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.604-611
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• 1998

High-speed railway trains entering and leaving tunnels generate finite amplitude pressure wave which propagate back and forth along the tunnels, reflecting at the open ends of the tunnels and at other discontinuities such as ventilation shafts and the train themselves. In present day railways, the magnitudes of the pressure waves are much too small to cause structual damage, but they are a serious potential source of aural discomport for passengers on unsealed trains. Almost always do the pressure waves propagating along the tunnels lead to a hazardous impulse noise near the exit portal of the tunnel. In order to alleviate such undesirable phenomena, some control strategies have been applied to the compression wave propagating inside the tunnel. The objective of the current work is to investigate the effect of tunnel entrance hoods on the entry compression wave at the vicinity of the tunnel entrance. Three types of entrance hoods were tested by the numerical method using the characteristics of method for a wide range of train speeds. The results show that the maximum pressure gradient of compression wave can be considerably reduced by the tunnel entrance hood. Desirable hood shape for reduction of the pressure transients and impulse noise was found to be of abrupt type hood with its cross-sectional area 2.5times the tunnel area.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.1-13
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• 2022

A weighted linear combination of seismic fragility models previously developed for cut-and-cover railway tunnels was presented and the appropriateness of the combined model was evaluated. The seismic fragility function is expressed in the form of a cumulative probability function of the lognormal distribution based on the peak ground acceleration. The model uncertainty can be reduced by combining models independently developed. Equal weight is applied to four models. The new seismic fragility function was developed for each damage level by determining the median and standard deviation, which are model metrics. Comparing fragility curves developed for other bored tunnels, cut-and-cover tunnels for high-speed railway system have a similar level of fragility. We postulated that this is due to the high seismic design standard for high-speed railway tunnel.

• Fire Science and Engineering
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• v.34 no.4
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• pp.59-68
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• 2020

In this study, the authors designed a reduced-scale railway vehicle fire, which was necessary for evaluating the fire safety of railway tunnels using a reduced model. To overcome the shortcomings of the methods used in conventional reduced-scale railway tunnel tests, the authors simulated the fire source of a railway vehicle using a methanol fire source for fire buoyancy, and a smoke cartridge for smoke visualization. Therefore, the heat release mass consumption rates of various methane trays were measured using a cone calorimeter (ISO 5660). The critical ventilation velocity in the railway tunnels was obtained using the designed fire source of the railway vehicle, which was evaluated by the measured temperature at the top of the tunnel as well as laser visualization.

• Journal of the Korean Society for Railway
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• v.8 no.4
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• pp.348-353
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• 2005

In designing the structures of railway rolling stocks, deterministic methods associated with the concept of a safety factor have been traditionally used. The deterministic approaches based on the mean values of applied loads and material properties have been used as safety verification for the design of rolling-stock car body structures. The uncertainties in the applied loading for the high speed train and the strength of new materials in the rolling stocks require the application of probabilistic approaches to ensure fatigue safety in the desired system. Pressure loadings acting on the car body when the train passes through tunnels show reflected pressure waves for high-speed trains and they may cause a fatigue failure in vehicle bodies. Use of new material technology as body structures also introduces uncertainties in the material strength. A probabilistic approach is more adaptable in designing reliable structures when the pressure waves from the tunnels pounds and new material technology is adopted. In this paper, it is proposed that a fatigue design and assessment method based on a reliability which deals with the loading variations on a railway vehicle due to the pressure reflected in tunnels and the strength variations of material. Equation for the fatigue reliability index has been formulated to calculate the reliability assessment of a vehicle body under fluctuating pressure loadings in a tunnel. Considered in this formulation are the pressure distribution characteristics, the fatigue strength distribution characteristics, and the concept of stress-transfer functions due to the pressure loading.

• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.364-369
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• 2012

This paper presents an experimental study on the radio propagation characteristics in subway tunnel at 18GHz frequency band which has been assigned to video transmission between train and wayside. The radio propagation tests are carried out in the subway tunnel of Seoul Metro using the antenna and communication devices of the prototype video transmission system. The measurement results show that 18GHz radio propagation in subway tunnel has smaller path loss than that of general outdoor radio environment. It is also cleared that the arch-type tunnels have smaller radio propagation losses than rectangular tunnels, and single track tunnels have smaller pass loss than double track tunnels. From the measurements, the radio propagation coverage is worked out as 520 meters. The curved tunnels which cannot have LOS communication between transmitter and receiver have large pass losses and fluctuation profile along distance. The radio propagation coverage along curved tunnels is worked out as 300 meters. These investigation results can be used to design the 18GHz radio transmission system for subway tunnel by providing the optimized wayside transmitter locations and handover algorithm customized to the radio propagation characteristics in subway tunnels.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.6
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• pp.625-635
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• 2013

Although the TBM method is mainly adopted in overseas market including the Europe, etc, the method scarcely adopted in domestic market. For highly enhancing applications of the TBM method for railway, It is needed to select the optimal cross-section considering design elements of civil engineering and aerodynamic effects. Also, it is needed to establish plan of proper section as well as reviewing aerodynamic effects and consideration about civil engineering elements such as length of tunnel, speed of railway, height of whole lines and size of utility tunnel, etc. Even though it should be recently considered high-speed railway tunnels and required to be standard establishments in aerodynamic reviews, it is being applied to be criteria of inconsistent pneumatic analysis owing to be not related with domestic standards. In this study, therefore, we are willing to establishment of domestic and foreign aerodynamic standards and investigate correlation between optimal cross-section and aerodynamic effects of TBM railway tunnels.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1171-1176
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• 2011

According to the 'Rules on the Safety Standard of Railroad Facilities', the 'Detailed Safety Standards of Railroad Facilities' and 'the Standards for Railroad Design' unified of MLTM(Ministry of Land, Transport and Maritime Affairs), the risk analysis on the application of fire safety facilities should be quantitatively performed to ensure the safety in tunnels over 1km long. This paper aims at proposal of basic data for the safety facilities' planning with reasonable and appropriate scale through case studies on different model tunnels.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.410-415
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• 2001

Conventional Korean tunnel portals require a lot of overburden as, fer static reasons, about 1.5 to 2.0 times the tunnel diameter is needed for the height in order to achieve a sufficient arching effect. Thus, considerable movement of earth and support constructions are required which lead to undesirably large changes of and damage to the environment. With a massively designed pipe roof, tunnels with little overburden can be built. For the effective construction of a pipe roof as an advancing safeguarding method, the following properties are indispensable： stability, insensitivity to settling and drilling accuracy. With the AT casing system a new pipe roof method has been developed which on the one hand entirely combines the properties mentioned last, and which on the other hand permits safe, economical and environmentally friendly construction of tunnels at low overburden heights of 3 to 6 m.

• Proceedings of the KSR Conference
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• 2003.10a
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• pp.181-186
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• 2003

In order to develop a high speed train, various conditions have been considered. Fatigue strength assessment by the fluctuation of pressure is an important one. In this study, a numerical simulation has been performed to estimate the fluctuation and frequency of pressure when KHST(Korean High Speed Train)passes through tunnels in the Kyung-Bu high-speed railway. The simulation was based on KHST running the Kyung-Bu high-speed line with the speed of 350km/h and the interval of 10 minute headway. And the tunnel entrance speed was estimated by TPS program. Therefore, the fluctuation and frequency of pressure is expressed in Weibull distribution function in the above running situation. The result in this study would be good guidance to calculate the fatigue life and the index of reliability of body structure. We are going to conduct more study to measure the real value of the pressure of the carbody passing through tunnels, to assess the fatigue reliability and to develop method ＆ procedure for the fatigue reliability design.