• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.3
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• pp.215-222
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• 2010

An experimental study was carried out on a reduced scale model tunnel to investigate the efficiency of disaster prevention at underground and ground ventilation equipments for the fire in road tunnels. Based on Froude modeling, the 1/50 scaled model tunnel (20 m long) was manufactured. The vertical shafts that are used in the analysis of efficiency of disaster prevention are the two models that had considered when the real tunnels are designed and the amounts of smoke exhaust are applied the miniature of the real tunnels' smoke exhaust, 560 and $280\;m^3/s$. As the result of analysis, it is the possible the emissions of the entire quantity of CO gas through the vertical shafts. In the ground ventilation equipments, the concentration of CO is discharged 2.23~2,73 ppm smaller than the underground ventilation equipments. And the temperature rise in the ground ventilation equipments is $0.53{\sim}0.94^{\circ}C$ lower than in the underground ventilation equipments because of a cooling effect of the surface of the tunnel wall. As a result of analysis of CO concentration and the temperature rise in the modeling ventilation equipment, the position of ground ventilation equipment is more effective than the underground ventilation equipment in disaster prevention measures.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.3
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• pp.213-221
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• 2009

This paper presents the concrete placement method of tunnel lining to improve the concrete lining quality such as cavities, cracks of the concrete lining. In order to perform this study, the occurred cracks initially in the concrete lining are reviewed and analyzed. From the review, the improvement methods to minimize the defects of concrete lining are suggested. To confirm the efficiency of new concrete placement approaches and the scale of tunnel section, two types of the scaled model tests are carried out and analyzed in model scales of 1/20 and 1/7. The 1/20 scaled model tests are carried out using the existing experimental rigs. The 1/7 scaled model tests are carried out in new test rigs developed in this study. The concrete placement rates obtained from the experimental results are analyzed and compared with themselves. In the existing concrete placement method, 1/20 scale model test than 1/7 scale model test have increased concrete placement rates but It is clearly found that two kinds of experimental studies show the similar results in improvement methods and good agreement with new concrete placing approach.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.4
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• pp.411-417
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• 2009

The thermo-flow field in road tunnel is influenced by some facts such as piston effect of vehicle's move, operation of ventilation facilities, natural wind and buoyancy effect of fire plume. Among those, piston effect is one of primary causes for formation of air flow in road tunnel and has an effect on initial direction of smoke flow in tunnel fire. In this study to analyze the unsteady flow in the tunnel caused by the run of vehicle, the experimental study of vehicle-induced unsteady flow on a reduced-scale model tunnel is presented. While the three types of vehicle shape such as basic type of rectangular shape, diamond-head type and stair-tail type are changed, the pressure and air velocity variations with time are measured. The rising ratio of pressure and velocity are in order of "basic type of rectangular shape > stair-tail type > diamond-head type". The experimental results would be good data for development of a numerical method on the vehicle-induced unsteady tunnel flow.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.1-12
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• 2024

Purpose: The objective of this study was to improve the tunnel maintenance and monitoring technology by establishing the maintenance, management, and monitoring standards for shield and TBM tunnels, which had been applied more in recent years. Method: This study comprehensively analyzed and compared the data and model simulations of Seoul Subway Lines 7 and 9 and Bundang Line, shield and TBM tunnels in South Korea, tunnels in France and Japan, and Channel Tunnel in the UK. Result: This study set maintenance and monitoring standards when there was no design estimate based on numerical analyses such as section design and section analysis regarding the maintenance and monitoring section of shield and TBM tunnels. Conclusion: It is necessary to determine safety by comprehensively considering not only each monitoring item but also the changing trend and correlation of all items and compensation of the tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.4
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• pp.295-304
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• 2005

The smoke propagating distances are measured in case that a fire occurs within the subway railroad tunnel. The tunnel is 800m long and the dimension of the cross-section is. Three vertical shafts exist for smoke ventilation. The experiments are performed using the 1/50 reduced-scale model. The smoke propagating distances are measured by thermocouples and by visualization for the accuracy. In order to understand the effect of a fire size and ventilation capacity of the shafts on the smoke propagating distance, 9 test scenarios are chosen. Based on the results, the smoke propagating distance is shown to be important criteria for the ventilation design of the tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.1
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• pp.91-97
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• 2007

Loads on the pillar and ground deformation in 2-arch tunnel, which is excavated in the rock mass with regular discontinuities, depending on the dips of discontinuities and the construction sequences were experimentally studied. Large scale model tests in the biaxial test facility were performed. Tested model (width 3.3m, height 3.0m, and length 0.45m) for 2-arch tunnel in 1/10 scale were built with various dips. Test results show that discontinuities have greate affects on the behavior of the 2-arch tunnel, especially on the pillar loads and ground deformation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.3
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• pp.197-207
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• 2005

Design analysis for underground spaces requires evaluating stability related to heading collapses. A failure mode is one of the critical factors in the conventional methods of stability evaluation. Identification of failure modes is, therefore, essential in securing safe construction. In this study failure modes at the tunnel heading in cohesionless soils are investigated using physical model tests for various tunnel depths and ground surface inclinations. Test results showed that the effect of depth and the inclination of ground surface on a failure mode are of significance. It is identified that, with an increase in depth, failure modes become localized in a region close to tunnel face. It is also known that an increase in the inclination of ground surface results in inclined an d wide failure modes. Numerical simulation of laboratory tests was performed, and shown that the numerical analysis is useful in identifying the heading failure modes, particularly for large underground spaces.

• Tunnel and Underground Space
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• v.9 no.2
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• pp.114-130
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• 1999

It is very important to study on the structural behaviors of structurally damaged tunnel linings. A series of centrifuge model tests were performed in order to investigate different behaviors of tunnel linings. A 1/100-scaled aluminum horseshoe tunnel linings with a radius 5 cm, height 8 cm were buried in a depth with dry Joomunjin standard sand, the relative density of which was 86%. Such sectional forces as bending moments and thrusts along the tunnel circumference were measured by twelve strain gages. Earth pressures in soil mass and on the outside of lining model were estimated by pressure transducers, ground surface settlements at a center and edges by using LVDTs.

• Journal of the Korean Geotechnical Society
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• v.28 no.2
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• pp.23-31
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• 2012

The purpose of this study is to analyze earth pressure acting on a circular shaft-tunnel considering arching effect by centrifuge modeling test on sands. The centrifuge testing method provides a way to model an in-situ stress state condition with a stress gradient within a laboratory specimen. A small-scale model of circular shaft-tunnel, which has a real diameter of 6.0 m and height of 15.0 m, was designed and tested twice under 75g-level. Additionally, an effect of excavation was presented by separating two segments of circular shaft wall to find behavioral properties and strength of earth pressure along with excavating ground. The test results were compared with those of the proposed earth pressure equation. The test results showed that earth pressure decreased by about 70% in comparison with existing two-dimensional earth pressure. This fact might be attributed to three-dimensional arching effects.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1794-1801
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• 2008

Fire-driven flow and temperature distribution in a ventilated tunnel was analyzed by Large Eddy Simulation using FDS code. The simulated tunnel is 182m length, 5.4m wide and 2.4m height. A pool fire was located 112m from tunnel entrance and was taken as a heat source of $0.89m^2$. The heat is assumed to be released uniformly throughout the whole simulated time. The fire strength was 2.76MW and the fuel burnt was octane. The parallel computational method was employed to accelerate the computing time and manage the large grid points which is not possible to handle in the one CPU. The total grid points used were $2.4{\times}10^6$ and 7 CPUs were used to calculate the momentum and energy equations. The simulated results were well compared with the experiments.