• Magazine of korean Tunnelling and Underground Space Association
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• v.2 no.1
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• pp.130-138
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• 2000

본 연구에서는 수평보강재로 보강된 터널 막장의 거동에 관한 매개변수 연구결과를 다루었다. 매개변수 연구에서는 막장주변의 3차원 응력-변형율 거동을 보다 효율적으로 모델링하기 위해 3차원 유한요소해석 모형을 적용하였으며 보강패턴에 따른 막장의 거동을 고찰하기 위해 다양한 경계조건에 대한 해석을 수행하였다. 해석결과를 토대로 막장의 응력해방-변위거동의 관계를 고찰하였으며, 보강패턴과 막장 변위의 정성${\cdot}$정량적인 관계를 제시함과 아울러서 향후 수행될 반경험적 설계/해석법의 개발을 위한 데이터베이스를 구축하였다. 한편, 해석결과 보강재 타설수 및 길이 등 각 보강설계 인자에 대한 임계치가 존재하는 것으로 나타났으며 따라서 보다 안전하고 경제적인 설계를 위해서는 이를 고려하여야 할 것으로 판단된다.

• Tunnel and Underground Space
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• v.14 no.4
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• pp.269-274
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• 2004

In this study reduced-scale experiments were conducted to determine the backlayering distance in tunnel fires. The 1/20 scale experiments were carried out under the Froude scaling using ethanol square pool fire ranging from 8 to 1km in each side with total heat release rate from 2.47 to 12.30 ㎾. It has been found that ventilation velocity increases with aspect ratio(tunnel height/tunnel width). At L$\_$B/$\^$*/ ＜5 the ventilation velocity increases proportional to the backlayering distance from 0.25 power of the heat release rate. However at L$\_$B/$\^$*/ $\geq$5 the ventilation velocity varies as the 0.3 power of the heat release rate.

• 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.

• Explosives and Blasting
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• v.24 no.2
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• pp.9-22
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• 2006

In general, tunnel construction except for special cases such as very short tunnels must require an artificial ventilation system. Especially, it is efficient for long tunnels to use the combination of a proper ventilation system according to the progress of the excavation. Neung-Dong Tunnel of which length is 4,580m has been originally designed as using ventilation system of blower and exhaust mixture types. Since it has been expected to result in some problems, its design Is analyzed to find the way to improve ventilation system by estimating the amount of required fresh air, considering various ventilation mixture types, ventilation's fluidity analysis and contaminant's distribution by numerical analysis. Economical efficiency for each type is also reviewed to determine the best ventilation system.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.211-224
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• 2018

It is important to design tunnel support system considering the various loads acting on the tunnel because they have a direct impact on the stability of tunnels. In Korea, standardized support patterns are defined based on the rock mass classification system depending on the project, and it is stated that it should be modified appropriately considering the behavior of tunnel during construction. In this study, the tunnel support pattern optimization method is suggested based on the convergence-confinement method, earth pressure, axial force of rock bolt, and moment acting on the shotcrete. The length and spacing of the rock bolts and the thickness of the shotcrete were optimized by using the differential evolution algorithm (DEA) and the results were compared to the standard support pattern III for railway tunnel. Rock bolt length can be reduced and the installation interval can be widened for shallow tunnel. As the depth of tunnel increases, the thickness of shotcrete increases linearly. Therefore, the thickness of shotcrete should be thicker than the standard support pattern as the depth of tunnel increases to secure the stability of tunnel.

• Tunnel and Underground Space
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• v.15 no.6 s.59
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• pp.432-440
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• 2005

Baehuryeong tunnel connects Chuncheon with Hwacheon in Kangwon, Korea, This tunnel is a single tunnel with 5,057 m long and two bidirectional lanes which will be extended into low lanes in the future. The estimated construction period of Baehuryeong tunnel is approximately 55 months. This tunnel will become the longest bidirectional roadway tunnel in Korea. Compared to a twin tunnel, a bidirectional single tunnel has two major disadvantages with regard to the ventilation system and ease of escape during fire. For these reasons, a service tunnel and the transverse ventilation system are planned first time in Korea. In case of fire, the tunnel ventilation design aims to maintain a smoke free layer for passenger evacuation. The geology of Baehuryeong tunnel site is mainly composed of gneiss and granite. Baehuryeong fault is a mainly large scale fault which stands vertical and parallels with tunnel direction. The influenced zone of this fault is within 70 m. Baehuryeong tunnel was designed that it was separated with the distance of more than 100 m from Baehuryeong fault for its safety.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.151-158
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• 2011

Tunnel sections on the expressway are different from rest of sections on the expressway in terms of velocity, the number of passing cars, and vehicle density which, in particular, affect drivers' behavior before and after drivers pass through the tunnel. However, literature review reveals that former studies are too focused on quantitative indicator to consider qualitative aspects. Thus, this study tried to find out qualitative factors affecting speed reduction in tunnel sections based on questionnaire surveys and its analysis in tunnel sections selected by taking consideration of diverse conditions. Analysis showed that factors concerning tunnel configuration (lane width, shoulder width, and tunnel length) related to very long tunnels increasingly popular recently had some effects on reduced speed inside of tunnels. It appeared that visual environment such as visibility of tunnel entrance had an impact in speed reduction and vehicle speed tended to change according to lighting illumination level inside of tunnels. It is expected that continual investment would be made in technological development related to expressway tunnel design and service improvement based on this study.

• Tunnel and Underground Space
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• v.28 no.5
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• pp.442-456
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• 2018

Scaled model tests were performed to evaluate the reinforcement effect of rock bolts in anisotropic rock mass. For this purpose, two tunnel cases were experimented which had different tunnel sizes, rock strengths, anisotropic angles and coefficients of lateral pressure. The fully grouted rock bolts of the D25 deformed bar were modeled as the basting pins with bead and were systematically installed at the roof and the side wall of the model tunnel. As results of the first case experimentations, the unsupported model showed initial crack at the roof of tunnel, but the supported model with rock bolts showed initial crack at the floor of tunnel where rock bolts were not installed. The crack initiating pressure and the maximum pressure of the supported model with rock bolts were 11% and 7% larger than those of the unsupported model, respectively. Moreover, the effect of the existing discontinuities in anisotropic rock mass on the fracture behavior of tunnel was reduced in the supported model, and so the reinforcement effect of rock bolt turned out to be experimentally verified. As results of the second case experimentations considering different support patterns, the crack initiating pressures of models were larger and the reduction ratios of tunnel area according to applied load were smaller as the length and the quantity of rock bolts were larger. Therefore, it was found that the performance of the rock bolts turned out to be improved as they were larger.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1D
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• pp.83-91
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• 2008

This study establishes the model to estimate a work time and a machine equipment combination in a NATM tunnel. Also it includes the increasing rate of haulage distance in the model for to make near to reality model. A simulation model focuses on the mucking process which affects the work effectiveness very highly to plan of machine use in tunneling operation. With the analysis of work effectiveness through tunnel simulation model, it is defined the problem of planning phase. Also it shows the optimal working time and efficiency of machine used through change the number of dump truck and haulage distance.

• Journal of the Korean Chemical Society
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• v.51 no.2
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• pp.125-128
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• 2007

In applying Numerov-Cooley method, Excel tool ‘Solver' is used to match those two wave functions propagated inward and outward, respectively. It is numerically confirmed that the same eigenvalue is obtained by using the average of two energy values of each inward and outward wave functions. This method is applied to a NO molecule potential, and we calculated the variations of the average bond distance and tunneling for a given vibrational energy. It is found that the average bond lengths increase proportionately to the vibrational energy, while the tunneling is not so sensitive to the energy changes. Rather substantial amount of tunnel effect is found for every vibrational state.