• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.345-356
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• 2004

Open-cut method has been widely used to construct underground structures, but it causes several problems such as traffic congestion and public resentment resulting from severe construction noise and ground settlement. In many cases, it is very difficult to build underground structures safely due to the unknown locations of buried facilities such as water pipes, drainage pipes, gas pipes and high-pressure cable conduits etc. Also in open-cut method, moving buried facilities causes additional cost and extension of construction period. Therefore, this paper is to present a case study in which Tubular Roof construction Method (T.R.c.M.), a newly developed construction method for underground structures using slab steel pipes and PC wall trench, is applied for the construction of a subway tunnel in Seoul. As a result, it is found that T.R.c.M. is a construction method by which tunnels can be constructed safely without any effect on the surrounding environment and traffic flow due to the minimized construction vibration and noise.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.403-409
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• 2000

It is very important to control the final load that acts on a support system, in tunnel engineering. A reliable analysis is needed to carry out technically reasonable design and safe construction. Also, a series of procedures of construction and the rock-support interaction behavior must be considered. Most existing studies have been performed as the limited analysis based on the simplified assumption. In this study, through the analysis of a circular tunnel using a 2-D finite differential code, the rock-support interaction behaviors in the variation of rock and stress conditions are analyzed and compared with the results from the closed form solutions. Consequently, more realistic rock-support interaction curves are obtained by including the effects of initial stresses and rock condition. These curves are very useful to predict the required support pressure in the initial design stage.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2004.04a
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• pp.199-217
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• 2004

터널 설계에 있어 갱구부의 위치 및 갱문형식의 선정은 터널 및 갱구사면의 안정성뿐만 아니라, 주위환경과의 조화 및 자연환경 훼손 최소화 등과 같은 환경적인 측면에서도 매우 중요한 부분이다. 현행 국내의 경우 경제성과 시공성 위주의 갱구부 위치 선정으로 과다 절취구간이 발생되어 환경훼손, 민원문제 발생, 과다한 용지 매입비용 등의 여러 가지 부작용이 발생되고 있다. 또한, 갱문 형식의 선정에 있어서 갱구부의 지형여건 및 제반 환경적 영향을 고려하지 않고 원통절개형과 면벽식 갱문의 획일적인 적용으로 주변지형과의 부조화를 이루는 사례가 다수 발생하고 있으며, 갱구부 상단의 유실된 토석이 완충공간의 부족으로 도로 노면상에 낙하되는 사고가 발생하고 있어 그에 대한 대책이 필요한 실정이다. 이와 같은 문제점을 보완하기 위해 갱구부 절취구간 최소화를 위한 구체적인 최소토피고 기준을 마련하였으며, 갱구상단 지형경사의 완급, 갱문주위의 배수기능, 낙석${\cdot}$산사태 등의 발생가능성 등을 고려한 새로운 갱문형식을 제안하고 체계적인 검토를 수행하였다. 이를 통해 점차 강화되는 환경보호정책 방향에 부응하고 자연환경 훼손을 최소화하며, 특히 해빙기와 집중호우시 낙석${\cdot}$눈사태로부터 도로의 안전을 확보할 수 있는 터널 갱문부 설계기준을 제시하였다. 또한, 실제 고속도로 터널의 설계 적용사례를 통하여 본 설계기준의 적용성을 분석하였으며, 실제 갱문 시공사례를 소개하여 향후 설계 및 시공에 도움이 되고자 하였다.

• Korean Journal of Construction Engineering and Management
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• v.8 no.3
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• pp.106-115
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• 2007

The size and length of road tunnels have been gradually expanded as industry developed. Consequently, the risk has been increased. The decision making process for ventilation system for road tunnels involves a large amount of information on economic feasibility, construction methods, and safety etc. In situation where systematically structured decision making process is unavailable, almost decisions about ventilation systems are made based on engineers' private knowledge and experiences. Procedure and criteria to choose the best optimized ventilation system among many alternatives are proposed, breaking away from the economic dependency-oriented decision making. This paper presents a Multi-Attribute Utility Theory and AHP based function with which planners can calculate overall utility of each alternative. It is anticipated that the effective use of the proposed methodology for decision making on ventilation systems ould be able to reduce the likelihood of the occurrence of potential safety risks as well as increase the overall ventilation performance.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.3
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• pp.47-59
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• 2007

IPv4 NAT, which often used in households or under SOHO environments, is one of the factors that delays IPv6 propagation. As IPv4 NAT does not operate properly under the transition mechanism like ISATAP or 6to4 that acts as IPv6-in-IPv4 tunneling type, Microsoft proposed Teredo in order to resolve this issue. However, tunneling transition mechanism like Teredo has a security problem. That is, being tunneled packets have dual IP headers; general firewall systems apply the filtering rules only to the outer header but not inner header when these packets pass the firewall. Furthermore, attacks using unregistered server and relay can take place in Teredo. To resolve these problems, we propose a new packet filtering mechanism exclusively for Teredo. The proposed packet filtering mechanism was designed and implemented by using Linux Netfilter and ip6tables. Through functional and experimental performance tests, this packet filtering system was found operating properly and solving the Teredo packet filtering problems without serious performance degradation.

• Tunnel and Underground Space
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• v.16 no.3 s.62
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• pp.218-231
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• 2006

Anisotropic/heterogeneous rock mass shows various deformation behavior types due to tunnelling because deformation behavior is largely controlled by the spacial characteristics of geological factors such as faults, joints and fractured zone in rock mass. In this paper 2-dimensional numerical analysis on the several influencing factors is performed considering fractured zone located near tunnel. This numerical analysis shows that deformation behavior of tunnel are very different according to the width and the location of fractured zone and supper method. However, 3-dimensional analysis is necessary to consider 3-dimensional geometrical characteristics sufficiently since discontinuity and fractured zone have 3-dimensional geometry. Also flexible design/construction guidelines for tunnelling are required to cope with uncertain ground condition and circumstance for technically safe and economic tunnel construction.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.321-331
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• 1998

A reliable analysis of tunnelling is needed to accomplish technically sound design and safe and economical construction. For the reliable analysis, a series of procedures of construction which include excavation and support stages must be considered. In this study, rock-support response behavior is studied and simulated in 2-D and 3-D finite element methods. Through the analysis of rock-support response behavior, the effects of the properties of shotcrete on the load distribution ratio can be quantified. The load distribution ratios for different rock types, different unsupported spans and various lateral earth pressure coefficients can be determined from the results of the 3-D finite element analysis. This load distribution ratios can be applied to a practical tunnel design through understanding of the trend of those various factors affecting the rock-support interaction.

• Fire Science and Engineering
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• v.20 no.4 s.64
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• pp.58-64
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• 2006

Smoke extraction in tunnel fire is investigated experimently with thermal model. The object is a immersed tunnel, of which the partial extraction system exists between the tubes. The model tunnel is measured 12 m long, 0.5 m wide and 0.35 m high. The fire is simulated to pool fire and the size corresponds to full scale fire of 5 MW based on Froude modeling. The performance of partial extraction system is determined under two ventilations, natural and longitudinal ones. The results show that compared with longitudinal ventilation, the smoke extraction efficiency of natural ventilation is increased about 30% because of smoke stratification in tunnel. Also the efficiency is identical to the iso-thermal model. The results will be help for activation of the ventilation system in emergency such as in the event of tunnel fires.

• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.29-40
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• 2019

Mechanized constructions have been frequently increased in soft ground below sea bed or river bed, for urban tunnel construction, and for underpinning the lower part of major structures in order to construct a safer tunnel considering various risk factors during the tunnel construction. However, it is difficult to estimate the subsidence behavior of the ground surface due to excavation and needs to be easily predicted. Thus, in this study, when a twin tunnel is constructed in the soft ground, it is proposed a simpler equation relating to the settlement behavior and a corrected formula applicable to soft ground and large diameter shield tunnels based on the previously proposed theory by Peck (1969). For this purpose, it was analyzed to long-term measurement values such as the amount of maximum settlement, the subsidence range by ground conditions, and interference volume loss due to the parallel construction, etc. As a result, a equation was suggested to predict the amount of maximum settlement in the soft sediment clay ground where is located at the upper part of the excavation site. It is turned out that the proposed equation is more suitable for measurement data in Korea than Peck (1969)'s.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.3
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• pp.451-460
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• 2019

It is critical for Korea to make effective use of limited space as it has dense population and high traffic volume compared to its terrestrial area. To resolve this issue, diverse types of underground structures have increasingly been applied so far, and one of the most representative structures is double-deck tunnel. The construction period of the middle slab in the double deck tunnel constructed at the great depth can be considered as an important part after the tunnel lining construction in the whole process. In order to minimize the construction period required for construction of the middle slab in the double deck tunnel, it was proposed a method of the precast intermediate slab. In this study, it is suggested a mechanical construction process with dedicated equipments developed to improve the safety and the workability of erection of the precast middle slab than the current construction method using the existing mobile crane.