• Land and Housing Review
• /
• v.5 no.3
• /
• pp.169-177
• /
• 2014

Constructing urban public housing built adjacent railway site has the noise and vibration problem coming from operation of trains. Thus, anti-vibration plans utilizing anti-vibration pads must be established to minimize the impact of train noise and vibration from the tunnels on the residents of the public housing. Under various difficulties and expectation from the citizens, many efforts were taken to satisfy the amenity requirements on noise and vibration for the residential area. As a results, it can be recognized that amenity standards can be satisfied. But great caution is required to prepare ourselves for various situations that might occur during construction, especially considering that the relevant railroads are still under operation.

• Particle and aerosol research
• /
• v.9 no.2
• /
• pp.79-87
• /
• 2013

In this study, the characteristics of turbulent flow and collection efficiency for an one-stage electrostatic precipitator(ESP) with slit type collecting electrode for urban railway underground tunnels were obtained using computational fluid dynamics(CFD) commercial code FLUENT 6.3 and lab-scale experiments. The electrostatic precipitator was operated under high gas velocity(3~12m/s). Five different designs of collecting electrode, flat plate-type and a slit-type of 3mm, 5mm, 7mm and 10mm slit width and four various gas velocity(3, 6, 9, and 12m/s) were used and applied. A standard k-${\varepsilon}$ model in CFD commercial code FLUENT 6.3 was used for flow simulation. The flow simulation results showed that the turbulent intensity of flat plate-type was higher than slit-type under all gas velocity conditions and also the turbulent intensity of flat plate-type was increased continuously, but in case of slit-type was maintained at constant range. And, the turbulent intensity was decreased according to increasing of slit width. The experimental results showed that the collection efficiency of slit-type was higher than flat plate-type under all gas velocity conditions. And, over 6m/s gas velocity condition, the collection efficiency of 5mm and 7mm was highest, when compared to 3mm and 10mm.

• Tunnel and Underground Space
• /
• v.9 no.3
• /
• pp.214-220
• /
• 1999

In this study, the validity of items of RMR system is evaluated and the applicability of this system to the data measured in Korean sites if discussed. Database was constructed from 139 sites, which are composed of subways, railway tunnels and road tunnels. These sites are located nationwide. Analysis shows that original classification of Bieniawski is valid although it was derived empirically. But it has considerable rating difference (error) in the result of Korean application. Thus new classification systems of KRMRI and KRMR2 are suggested, which are deduced from the Korean database. The former includes adjusted ratings and the latter adopts two more items. These are deduced by artificial neural network because it is difficult to select \`characteristic value'to estimate rock quality.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.1289-1297
• /
• 2011

Objective of this study was to characterize $PM_{10}$ sources on subway tunnels and development of simple particulate matters measuring device based on wireless sensor network. A new wireless sensor module, PMX, has been designed and manufactured to measure $PM_{10}$ and$PM_{2.5}$ simultaneously. The measurements have been conducted at a specific subway station on the Seoul metro line. The accuracy of the device was verified and compared with commercial measuring device based on weighting method.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.125-132
• /
• 2000

This study presents the application of genetic algorithms(GA) to the back analysis of tunnels. GA based on the theory of natural evolution, and have been evaluated very effective for their robust performances, particularly for optimizing structure problems. In the back analysis method, the selection of initial value and uncertainty of field measurements influence significantly on the analysis result. GA can improve this problems through a probabilistic approach. Besides, this technique have two other advantages over the back analysis. One is that it is not significantly affected by the form of problems. Another one is that it can consider two known parameter simultaneously. The propriety of this study is verified as the comparison in the same condition of the back analysis(Gens et al, 1987). In this study, it was performed to estimated the geotechnical parameters in the case of weak rock mass at the Kyung Bu Express railway tunnel. GA have been shown for effective application to a geotechnical engineering.

• Tunnel and Underground Space
• /
• v.8 no.1
• /
• pp.53-66
• /
• 1998

Considering the mechanical cracking in the concrete lining of tunnels occurring in relatively short period of time after the construction, there is a need for the study on the mechanical behavior and the cracking characteristics of double lining support system(shotcrete and concrete lining). For the proposed study, downscaled lining models of Kyung-Bu High Speed Railway tunnels were tested. Most longitudinal cracks at about 93 percentage developed within 30 arch degree from the vault. Cracking load was about 30 percentage of the failure load and the deflection under the cracking load was 10 percentage of the deflection under the failure load. The overbreak around the vault contributed to the reduction of the capacity for cracking and failure by the percentage greater than the reduced effective depth. Of several rock block types considered in this research, the triangular block was the most critical, and the right triangular block under eccentric load was secondly critical for the stability of the tunnel lining system. The dimensionless support reaction curves were derived from the experimental results for single and double lining. The general equation to compute the designed flexural moment was modified.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.690-695
• /
• 2004

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, the fluctuation and frequency of pressure is measured when KHST(Korean High Speed Train) passes through tunnels in the Kyung-Bu high-speed line. And the characteristics of pressure fluctuation is analysed and formulated. The results of analysis are as follows. The train entering speed and fluctuation value are related. The pressure increasing is generated in proportion to train velocity at leading car. When two train is passing through the tunnel, the pressure value is $1.5\~2$ times higher than one train is passing. The damping ratio of pressure fluctuation is about $92\%$. The number of pressure fluctuation in a tunnel is 4 to 6 times. The result in this study would be a good guidance to calculate the fatigue life and the reliability index of body structure.

• Geomechanics and Engineering
• /
• v.15 no.3
• /
• pp.911-917
• /
• 2018

This paper concerns a numerical investigation on the effect of construction sequence on three-arch (3-Arch) tunnel behavior. A three-arch tunnel section adopted in a railway tunnel construction site was considered in this study. A calibrated 3D finite element model was used to conduct a parametric study on a variety of construction scenarios. The results of analyses were examined in terms of tunnel and ground surface settlements, shotcrete lining stresses, loads and stresses developed in center column in relation to the tunnel construction sequence. In particular, the effect of the side tunnel construction sequence on the structural performance of the center structure was fully examined. The results indicated that the load, thus stress, in the center structure can be smaller when excavating two side tunnels from opposite direction than excavating in the same direction. Also revealed was that no face lagging distance between the two side tunnels impose less ground load to the center structure. Fundamental governing mechanism of three-arch tunnel behavior is also discussed based on the results.

• Proceedings of the KSR Conference
• /
• 2005.05a
• /
• pp.498-503
• /
• 2005

In this paper, an experimental study is carried out to analyze the vibration characteristics of components of the ballast track and the slab track layed in HSL tunnels. According to vibration level test of ballast tracks and concrete tracks on HSL, the vertical vibration level of rails on concrete tracks is 6.2dB more than that on ballast tracks, and especially on $50{\sim}80Hz$ frequency band, the difference is more than 6dB. The orther track components according to track type are appeared to be smaller on the slab track than on the ballast track. Regarding car body vibration, 80Hz component, which was not remarkable while running on open tracks, is considerably amplified in tunnels where concrete tracks are laid.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1774-1781
• /
• 2007

In this study, Matsuda's formula, which has been used to evaluate the acting load on the concrete pillar in 2-Arch tunnels, is investigated and a load reduction factor $({\alpha})$, which has been estimated from numerical parametric studies, is proposed for a better design of 2-Arch tunnels in the future. Numerical parametric studies show that the concrete pillar is subjected to a stress concentration on the excavation side during the first tunnel driving and when tunnel excavation is completed, the induced stress on the pillar in a poor quality of ground condition is 1.5 to 1.8 times the stress developed during the first tunnel driving. In addition, the numerical studies indicate that the acting load on the pillar is in the range of $14{\sim}83%$ of the load estimated by Matsuda's formula. From these results, a load reduction factor $({\alpha})$ is determined and it would make 2-Arch tunnel design more economically.