• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.5
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• pp.375-393
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• 2022

This study was deal with blow-out and buoyancy stability evaluation method for slurry shield TBM. When applying a slurry shield TBM for the construction of a shallow tunnel under river or sea, the stability of slurry blow-out and segment lining buoyancy should be evaluated. However, there is a problem in that the currently applied theoretical formula is somewhat complicated, making it inconvenient to calculate in practice. In this study, some simple charts were proposed to easily evaluate the stability of slurry blow-out and segment lining buoyancy. In addition, the buoyancy safety factor of segment lining using the strength reduction method was evaluated and compared with the buoyancy safety factor based on the theoretical formula. The buoyancy safety factor by the theoretical formula was evaluated to be rather small, and it was confirmed that it was on the safe side. The simplified charts for the evaluation of slurry blow-out and buoyancy stability presented in this study are expected to be usefully utilized in the planning and design of undersea tunnels.

• Tunnel and Underground Space
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• v.19 no.6
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• pp.498-506
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• 2009

The stability assessment of a concrete liner of a compressed air storage tunnel should be performed by an approach which is different from that commonly used for the liners of road tunnels, since the liner is exposed to high air pressure. In this study, the stability analysis method for the liner of compressed air storage tunnel is proposed based on the elastic and elasto-plastic solutions of the thick-walled cylinder problem. In case of elastic analysis, the yield initiation condition at the inner boundary is considered as the failure condition of the liner, while the condition which results in the extension of yielding zone to a certain depth is taken as a failure indicator of the liner in the elasto-plastic analysis taking Mohr-Coulomb criterion. The application of the proposed method revealed that the influence of the relative magnitude of boundary loads on the stability of liner is considerable. In particular, noting that the estimation of the outer boundary load may be relatively difficult, it is thought that the precise prediction of outer boundary load is very important in the analysis. Accordingly, the emphasis is put on the selection of the liner installation time, which may govern the magnitude of outer boundary load.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2003.03a
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• pp.51-66
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• 2003

최근 용지매입의 제한과 자연환경훼손의 최소화를 도모하는 사회적 환경으로 인해 대단면 근접병설터널 계획이 점차 증가하고 있다. 지금까지는 주로 중앙벽체부의 지지기능을 활용한 2Arch터널의 형태로 도심지 지하철의 정거장이나 고속도로의 일부구간에 계획되고 있으나, 대단면 근접병설터널에 대한 시공실적 및 설계사례가 부족한 국내에서는 이에 대한 역학적 거동과 합리적 시공방안에 대한 연구가 미흡한 실정이다. 따라서, 대단면 근접병설터널에 대한 국내·외의 설계 및 시공사례를 정리·분석하므로서 차후 제한된 구간에서의 터널계획시 합리적인 설계 및 시공이 되고자 하였다. 또한, 최근 도심지 구간에 계획중인 터널의안정성 검토 사례를 중심으로 터널 및 인접구조물, 중앙필러부 및 콘크리트 라이닝에 대한 상세 안정성 검토방법을 고찰함으로써 기존 병설터널의 거동특성과는 구별되는 대단면 근접 병설터널의 안정성 평가기법에 대한 방향을 제안하였다.

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.33-45
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• 2007

In this study, the blast-induced vibration effects on the structural stability of the adjacent tunnel were estimated with respect to the allowable peak particle velocity (PPV). The blasting distance from the tunnel satisfying the allowable PPV was estimated based on the analytical solutions, United States Bureau of Mines (USBM) suggestions, and the equations used in the subway in Seoul. The allowable blasting distance was estimated by using finite difference analysis (FDA) and the behavior of the concrete lining and rock bolts was examined and the stability of those was estimated during the blast. Research results show that the blast-induced vibration effects on the structural stability are negligible for the concrete lining but relatively large for the rock bolts.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.1
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• pp.37-50
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• 2001

Recently, as tunnel structure is getting old, many deformations and defects have been occurred. As tunnel has the characteristics of underground structure, the estimation of the cause of deformation is very difficult. Then, it is necessary to investigate the state of tunnel lining and to estimate the deformation cause and safety for tunnel. In this study, inspection and diagnosis system for effective maintenance in tunnel was researched. Firstly, non-destructive techniques such as GPR (ground penetrating radar), impact echo test, and infrared thermal techniques were applied to tunnel lining inspection. Tunnel lining analysis system was developed to analyze the stability of tunnel. And, tunnel soundness evaluation system was developed to find the probable causes and indicate the method for repair and reinforcement for tunnel.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.150-159
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• 2011

The need of securing the stability and extending service lives by efficient maintenance of deteriorated tunnels for several decades has been increased. The stability and the usability of conventional tunnels can be decreased by change of physical properties of the surrounding ground, geometrical properties of the tunnel, an underground water level, environmental conditions, oxidation of lining and the breakdown of constituent materials. In respect of a long-term view, it is need to check all sorts of degradation, the degree of damage and durability to improve the serviceability and to come up with measures to maintain effectively. This paper is about study to analyze the stability of conventional tunnels(American Steel Support Method. ASSM). Three tunnels are chosen in those built in the 1930s and 1960s and the locations of tunnels are selected variously(ChungCheong, GyungBuk, GangWon, Jeolla, etc.) to secure reliability of this study. The state of repair and reinforcement of linings, cracks, and thickness and strength of lining of conventional tunnels in service are researched, compared and analyzed. The crack gauge, the GPR, the schmitt hammer was used for the crack investigation, cavitation, the strength respectively. By using these, the comparative analysis for conventional tunnels was conducted. As a result, there are more cracks in tunnels built in the 1930s than those of tunnels built in the 1960s, and lining strength of the 1930s is higher than those of the 1960s. The thickness of lining in tunnels built in the 1960s is higher than those in tunnels built in the 1930s. In proportion to thickness, cavitation occurred more frequently in tunnels built in the 1960s compared to those in tunnels built in the 1930s.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.389-399
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• 2016

Efficiency for estimation of subsea tunnel safety can be increased through reflecting back analysis algorithm to displacement measurements besides other measurement information such as stress, water pressure and ground stiffness degradation. In this study, the finite difference code FLAC3D built-in FISH language is used. In addition, the stability of the tunnel lining will be evaluated from the development of displacement-based algorithm and its expanded algorithm with conformity of several parameters such as stress measurements, water pressure measurements, tunnel lining degradation measurements and ground stiffness degradation measurements. By using additional measurement information to assess the stability of subsea tunnel, it was confirmed that the error rate is reduced to the tunnel back analysis.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.69-84
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• 2011

This paper presents the applicability of NATM Composite Lining method in domestic tunnel construction sites. Firstly, in order to produce high quality PC Panel, optimal steam curing condition is reviewed. And in preparation for fire inside the tunnel, the fire-resistance test of PC Panel is carried out. The constructability of NATM Composite Lining method and the drainage ability of light-weight foamed mortar is also evaluated through field construction test. And PC Panel combination program is developed to calculate the quantity of PC Panel efficiently. Besides, economic evaluation for NATM Composite Lining method is conducted. From this research, it is clearly found that NATM Composite Lining method is applicable to domestic tunnel construction site.

• Journal of the Korean Geotechnical Society
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• v.17 no.5
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• pp.197-207
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• 2001

1980년대 이래 국내 터널의 시공법은 원지반의 강성을 활용한 NATM이 주를 이루고 있다. 그러나 NATM은 터널내부에 설치되는 내부라이닝의 여러 가지 문제점을 내포하고 있기 때문에 노르웨이에서는 조립식 터널 라이닝(Pre-Cast Concrete Lining, PCL)을 개발하여 현장타설 콘크리트 라이닝의 문제점을 해결하고자 하였다. 그러나 노르웨이와 같은 북유럽지역에서는 지진이 거의 발생되지 않고 있기 때문에 PCL공법 개발당시에 지진에 대한 영향을 고려하지 못하였다. 따라서 PCL공법을 국내에 도입하기 위해서는 먼저 지진에 대한 영향을 분석하여야 할 것으로 판단되므로 본 연구에서는 PCL공법 적용시 지진에 대한 안정성 평가 및 합리적 내진해석을 위한 연구를 수행하고자 하였다. PCL의 내진성능을 판단하기 위하여 먼저 국내에서 주로 많이 사용되고 있는 해석기법인 유사정적해석법과 응답스펙트럼해석법을 이용하여 분석하였으며 지반과 구조물의 상호작용에 대한 영향을 분석하기 위해 시간이력해석을 수행하여 터널심도별 PCL의 내진성능을 분석하였다. 이와 같은 방법으로 PCL의 내진해석을 수행한 결과, 부재에 발생된 응력이 허용응력 이내에서 발생되어 PCL의 내진성능을 확보된 것으로 판단된다. 또한 시간이력해석에 의한 지반-구조물 해석을 수행한 결과에 의하면 PCL의 내진성능을 확보하기 위한 터널의 최소 토피고가 터널직경에 2배 이상인 것으로 확인되었다. 또한 단순 구조물의 내진해석만으로는 PCL의 내진성능을 과소평가할 우려가 있는 것으로 나타났다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.3
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• pp.227-235
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• 2006

The problematic issue of cracking, water shedding in tunnel is recently coming out in the view of the structural stability. Hence, the assessment is required for the existing tunnels to achieve the structural soundness of tunnels, and their safety and maintenance. In this study, fracture behaviour and displacement of a tunnel concrete lining using steel fiber reinforcement concrete was investigated. The specimens were fabricated in single lining for a model of real road tunnel. As parameters, load condition, thickness of lining, whether or not rear cavity in crown, and a ratio of steel fiber in concrete were taken. From these factors, the load for crack and fracture, displacement, and the pattern of crack were looked into for the structural stability of a tunnel concrete lining.