• Journal of the Korean GEO-environmental Society
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• v.10 no.1
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• pp.55-61
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• 2009

Recently, highway tunnel construction has rapidly been increased due to the limited ground usage and geographical characteristic in Korea, i.e. Korea consists of 70% mountains. In this paper, it was analyzed tunnel collapse patterns in the weathered rockmass. Recent tunnel collapse pattern is quite different from that of past ten years. Tunnels in past years have been collapsed at shallow valley area because of shear strength decrease after heavy rain. Tunnels, which have been constructed recently, were collapsed at even the deeper ground position after primary support. Also in the case that proper reinforcement was not applied, it caused excessive crack at shotcrete and local collapse near tunnel face. In this paper, it was analysed the cause of the recent tunnel collapses and proper reinforcement for the collapsed tunnels.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.6
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• pp.161-172
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• 2012

The purpose of this study is to classify, evaluate and grade the existing highway tunnels to increase landscape and natural statistics keeping the structural safety about tunnel gates area and induce the ones that will be constructed in the future by drawing the improvements and restoring the techniques as an environment-friendly. To examine the types of tunnel gate area, total 54 tunnels were investigated by selecting Gyeongbu Expressway, Yeongdong Expressway, and Jungang Expressway. Tunnel entrances and exit ports were classified as a Wall-closed type and Protruding type, which is based on tunnel gate type. Vegetation Landscape types were classified as Multilayer-Same as the surrounding landscape_(MS), Multilayer-Difference of surrounding landscape_(MD), Single layer-Same as the surrounding landscape_(SS), Single layer-Difference of surrounding landscape_(SD), and a Desolate type which based on vegetation layers and environment-friendly. Potential vegetation recovery was identified based on the structural stability and revegetation potential of the tunnel. The factors include the structural stability of the slope height and slope gradient were selected. Revegetation potential was identified as a growth potential. This factor was used in the step to classify vegetation recovery potential of a tunnel. The result, which investigated the types of tunnel entrances and exit parts has found that the most typical in 33 places was a Wall closed type with 61.1% of the total ones. The case of vegetation landscape types was created but different from the ones surrounding it with 85.2% of the total ones. It is judged that the currently constructed vegetation of tunnel entrance and exit parts had put convenience on the safety and management before landscape consideration. In addition, tunnel entrance and exit parts with excellent potential for vegetation recovery were all Protruding type. In addition, it is judged that slope stability can easily obtain growth. Therefore, entrance and exist of the highway tunnels, which will be constructed in the future, should reflect location and the result of the natural and ecological survey in design by performing it in advance and their types, which minimize the damage area range, should be applied to the local characteristics suitably. In addition, the ecologically healthy tunnel construction should be done by introducing active vegetation recovery techniques based on its safety.

• Korean Journal of Environment and Ecology
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• v.31 no.1
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• pp.104-111
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• 2017

The construction of road tunnels and bridges have delivered driving efficiency and stability based on developed engineering technology. Tunnels have the advantage of reducing the deforested area compared with other road construction methods. Since a tunnel is an underground passageway dug through the surrounding soil/earth/rock and enclosed except for the entrance and exit, commonly at each end, it does not cause a large amount of deforestation. This study surveyed the deforested areas at each end of the tunnel by the design of the tunnel entrance and exit and forest topography to minimize the amount of deforestation caused by road construction. A survey was done on a total of 150 tunnels (300 entrances and exits) on several main roads in Korea. The deforested area of each tunnel was collected by a breakdown of the entrance area and the upper area of the tunnel. According to the results of Kruskal-Wallis analysis, it was found that there was statistically a significant relation between the location of tunnels and the amount of deforestation by the topographical access type of the tunnels. The tunnel with 'facing orthogonal to incline' type access caused the smallest deforestation while the the tunnel with 'facing to valley' and 'parallel with incline' type accesses caused large deforestation during tunnel construction. Tunnel positioning in the light of topography can reduce the deforested area by up to 1.5ha at each tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.3
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• pp.13-24
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• 2000

The collapse shapes and causes of tunnel in the highway were analyzed and reinforced methods of tunnel were investigated in the paper. Collapse shapes of tunnel are divided into three types such as subsurface failure, small scale wedge failure and slickenside strata failure. These three shapes consist of 35%, 50%, and 15%, respectively. The 85% of collapse was located near the entrance and exit of tunnel. The 15% was located at the intersection of emergency laybys. When tunnel collapses are analyzed by the failure concept, sliding failure amounts to more than 83%.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.167-177
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• 2009

This study investigates a failure mechanism of a tunnel shotcrete lining with respect to a concentrated load due to blocky rock mass. First of all, it is carried out to survey relevant researches to shotcrete failures by literature reviews and to numerically re-investigate the failure modes of shotcrete lining given by previous researches. Through this study, the failure modes are relocated with the conditions which induce each failure mode newly proposed by this study. In addition to this, the arching shape of tunnel lining, which has not been considered in the previous research despite of inherent geometrical characteristics in tunnels, is taken into consideration in numerical investigation on lining failure in this study. As a result, it is shown that more simplified failure modes can be found on the tunnel boundary condition and the corresponding failure condition to each mode can be different from ones of the previous study due to a tunnel arching effect.

• Journal of Korean Society of Disaster and Security
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• v.14 no.3
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• pp.51-63
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• 2021

This study is for the quality improvement of water-sealing & reinforcement grouting in tunnel of the construction of the underground transportation network underneath the city. Existing tunnel grouting process did not technically utilize P~q~t charts fully. It is due to the absence of technical methods to decide how P~q~t charts change in the presence of trouble and what the change represents in grouting. There were no standards to decide which chart pattern represents which ground characteristics, how to categorize ground types, and how to take measures according to the standards. This paper studies on the grouting type, ground characteristics, ground type categorizing method, and countermeasures for both general and algorithm-processed grouting in soil and rock layer to address the aforementioned problems. Newly improved P~q~t charts from grouting in soil was categorized into six different types. Different characteristics and categorization method was developed for each type. Countermeasures for each type of grouting process were developed so that on-site application can be readily available. Improved P~q~t charts for rock layer also have six different types of grouting. Each type was given the countermeasures for rock layer grouting process for easier applications. Therefore, it is expected to be used through out the entire process of grouting from preparation to the last report of the water-sealing & reinforcement grouting in tunnel of the construction of the underground transportation network underneath the city.

• Magazine of korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.47-60
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• 2007

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.109-128
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• 2022

The precise inspection for safety and diagnosis (PISD) of tunnel has been conducted by the special act on safety control of public structures. However, the present assessment for the segmental lining of TBM tunnel has limitation such as: NDTs for integrity, segmental configuration for field inspection, and consideration for jacking system. Even if the number of TBM tunnel is less than 1% of enrolled facility in FMS, more attention to maintenance should be necessary due to its usage such as multi-use facility and national important facility. Compared to NATM tunnel, excavated by drilling and blasting and then installed lining by cast-in-place within 6~12 m, TBM tunnel is cut out ground by disk and cutter-bit and then assembled 7 pieces of precast segment, 1.2~1.4 m wide. Different features of design, construction, and maintenance should be considered to be more exact evaluation of TBM tunnel. The characteristics of defect is categorized and analyzed with 11 operational TBM tunnels in domestic subway. To be more comprehend various particular defects, foreign studies have been also adapted. Crack and leakage are categorized in 7 patterns. Breakage/spalling and corrosion are also grouped into 3 patterns. Patterned defects or damages are fed back in design, construction, and are useful guidelines for maintenance stage in future.

• Tunnel and Underground Space
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• v.9 no.1
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• pp.20-26
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• 1999

The completion of the Bakun Diversion Tunnel is subsequently to the Main Dam construction. Therefore, the completion date is very important for the Bakun Hydroelectric Project. Generally, the tunnel lining work as a finishing phase of the tunnelling project occupies a important portion as well as an excavation and a support work of the tunnels in respect to the construction cost and period. Internal section of Bakun Diversion Tunnel is designed circular shape to reduce the roughness of the water flow with 12 meters in diameter of total length 4314.6 meters of 3 tunnels. The lining thickness is varied between 500 mm and 700 mm depending on the structural condition. From the original Tender design of the Bakun tunnels, the required quantity of steel bars was 5,985 ton designed by Reinforced Concrete (RC) through the entire tunnel linings. During the detail design stage by the consideration of the rock conditions and various load conditions, we could suggest five kinds of RC lining type including plain concrete lining type. Through the detail design modification, we could reduce the required amount of steel bars to 2,178 ton, as a half of original Bill of Quantity. Finally, this design modification give us the time and cost saving effect to catch up the construction progress in time.

• Journal of the Korean Geotechnical Society
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• v.16 no.5
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• pp.117-127
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• 2000

터널 시공과 굴착과정에서 파쇄대, 절리, 연약대, 균열 등 암반에서의 불연속면은 중요한 역할을 한다. 본 연구에서는 지반 고유의 특징인 불확실성에 의한 터널 설계와 시공 과정에서 겪는 많은 시행오차를 최소화하기 위해서 국내의 터널 붕락 현장의 지반조사 자료를 분석하여 터널 붕락 유형 및 규모를 제시할수 있는 Geo-predict 시스템을 개발하였다. Geo-predict 시스템은 총 104개 터널 붕괴/붕락자료(국외84개, 국내20개)를 분석한 자료를 테이터베이스로 인공신경망 학습을 토해서 터널 붕괴 형태와 규모를 추론하는 시스템이다. 본 논문에서는 Geo-predict의 개발과정 및 구성.기능을 소개하였으며 104개 터널 현장 자료를 지반조건별로 분석하고 이를 데이터베이스화하여 인공신경함을 이용한 추론 시스탬을 구축하고, 2개 고속전철 터널현장과 1개 지하철 시공현장에 적용성 평가를 실시하여, 터널의 붕락 가능 및 붕락 규모를 추론하였다.