• Tunnel and Underground Space
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• v.10 no.3
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• pp.418-429
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• 2000

Many Studies of tunnel and tunnelling safety have been developed continuously based on the increasing social interests in underground space since 1990's in Korea. Because the growth of population in metropolitan has been accelerated at a faster pace than the development of the cities, underground facilities have been created as a great extent in view of less land space available. In this study, a lot of types of tunnel failure were surveyed and the detail causes were studied after many cases of tunnel failure were collected. There were suggested brief countermeasure of tunnel failure through case study. An expert system was developed to predict the safety of tunnel and choose proper tunnel reinforcement system using fuzzy quantification theory and fuzzy inference rule based on tunnel information database. The comparison result between the predicted reinforcement system level and measured ones was very similar. In-situ data were obtained in three tunnel sites including subway tunnel under Han river. This system will be very helpful to make the most of in-situ data and suggest proper applicability of tunnel reinforcement system developing more resonable tunnel support method from dependance of some experienced experts for the absent of guide.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.4
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• pp.335-341
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• 2005

In construction of a large cross section NATM tunnel, to keep the tunnel face stability by the ground itself bench cut method is commonly used. In order to necessity of partial face excavation method, we have to look for more enhanced method that can maintain better stress intensity. This paper presents a stress distribution of the Center Diaphragm Method from the partial face excavation methods, with the numerical analysis, and induced the optimal face distance, which is minimizing stress concentration and the optimal excavation step. Commerical 3 dimensional continuum analyzing FLAC-3D Ver. 2.1 program is used for the analysis. Analyses were performed to investigate ground behavior for tunnels with variable bench-length varying from 2m to 40m.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.549-557
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• 2017

In order to improve the productivity in the civil engineering field, efforts to apply BIM have been continuing, however, research on information modeling of tunnel structures considering alignment is insufficient. In this study, we proposed the method of building tunnel models reflecting curved alignment by transferring point data to BIM Authoring Tools(BAT) through discretization of alignment in Alignment-centered Modeling Tools(AMT). IFC data schema was derived to consider the physical and spatial elements of tunnel structures and alignment and IFC-based information management for tunnel alignment, tunnel structures and ground conditions was possible by referring to the extended data schema and including meanings in IFC property sets. The ratings for ground condition in Rock Mass Rating(RMR) and Q-system was automatically derived by using generated information model according to the proposed method.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.23-32
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• 2004

The local geologic and dynamic site characteristics, which include soil profiles, shear wave velocity profiles and depths to the bed rock were gathered from 148 sites all over the Korean peninsula and those values are compared to those in the western USA. Site response analyses were performed based on equivalent linear scheme using design rock-outcrop acceleration of 0.154g which corresponds to the collapse level of earthquake for seismic category I structure. The results show that the amplification factor based on Korean seismic design guideline underestimates the motion in short-period range and overestimates the motion in mid-period range. It is suggested that the existing Korean seismic guideline based on UBC is required to be modified considering dynamic site characteristics in Korea for the reliable estimation of site amplification.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.1
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• pp.37-45
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• 2021

The construction of the tunnel portal should be careful because cover depth is shallow and it is difficult to exhibit the arching effect. Tunnel stability may be reduced with additional embankment above the portal of tunnel. In this study, in order to examine the stability of the tunnel according to additional embankment above the portal of tunnel, numerical analysis was performed while changing the ground conditions and height of embankment. As a result of the numerical analysis, it was found that the allowable flexural compressive stress of shotcrete and allowable axial force of rockbolts were exceeded when the height of additional embankment was 12 m in rock mass rating V. When considering the displacement, the range of the plastic region and the behavior of the support materials, the tunnel stability seems to be greatly reduced if the height of additional embankment above the portal of tunnel exceeds 10 m.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.1
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• pp.1-11
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• 2023

In this study, the stability of the room-and-pillar underground method was investigated using numerical analysis method. In-situ geotechnical investigation was conducted, and a supporting pattern was selected based on the geotechnical investigation data. For the supporting pattern, Type-1, 2, 3 were selected for each ground condition. A 3D numerical analysis model was developed for effective simulation as the room-and-pillar underground method consist of a pillar and room. As a review of numerical analysis, it was confirmed that the crown settlement, convergence, shotcrete and rock bolt were all stable in all supporting patterns. As a result of the analysis by the construction stage, it was confirmed that excessive stress was generated in the room when the construction stage of forming pillar. So, precise construction is required during the actual construction stage of the pillar formation.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.115-124
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• 2022

This study was conducted to obtain basic data that could help prevent damage caused by slow-moving landslides (land-creep). Specifically, the geological, topographic, and physical characteristics of land-creep were analyzed in Jiphyeon-myeon, Jinju-si. The first and second analyzed land-creeps occurred in 1982 and 2019, respectively. The area damaged in the second land-creep was about 11.5-fold larger than that damaged in the first land-creep. The dominant constituent rock in the land-creep area was sedimentary rock, which seems to be weakly resistant to weathering. The areas that collapsed due to land-creep were related to the presence of separated rocks between the bedding plane in the estimated activity surface over the slope direction and the vertically developed joint surface. Thus, surface water and soil debris were introduced through the gaps of separated rocks. Additionally, the areas collapsed due to the combination of the bedding plane and joint surface shale and sandstone showed an onion structure of weathered outcrop from the edge to inner part caused by weathering from ground water. Consequently, core stones were formed. The study area was a typical area of land-creep in a mountain caused by ground water. Land-creep was classified into convex areas of colluvial land-creep. The landslide-risk rating in the study area was classified into three and five classes. The flow of ground water moved to the northeast and coincided with the direction of the collapse. Soil bulk density in the collapsed area was lower than that in ridge area, which was rarely affected by land-creep. Thus, soil bulk density was affected by the soil disturbance in the collapsed area.

• Korean Journal of Plant Resources
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• v.35 no.2
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• pp.201-241
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• 2022

This study was investigated distributed the vascular flora of around Haemyeong Mt., located in Seokmodo, Incheon, and compared invasive alien plants in the surrounding forest 14 areas. This study carried out to be established a monitoring system for the remarkable plants etc. and used as basic data for biodiversity enhancement and conservation. The survey was conducted 19 times from April 2019 to October 2020. A total of 107 families, 382 genera, 616 species, 15 sub-species, 55 varieties, 8 formas, and 694 taxa were classified in the flora around Haemyeong Mt. areas. 17 taxa for Korea endemic plants. 12 taxa were classified for rare plants, and a total of 79 taxa were identified for floristic target species I~V. Halophytes consisted of 37 taxa. The invasive alien plants were classified as 66 taxa, and also there has been 126 taxa of them in Seokmodo and surrounding 14 forests. Plants that appeared in all 14 areas out of 126 taxa were classified as 7 taxa, such as Erigeron annuus. However, 48 taxa appeared only once in some areas, but it seems inevitable that they will spread in the future. Therefore, it is necessary to prepare a long-term conservation plan for native plants.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.5
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• pp.336-340
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• 2004

The objective of this study was to establish the decision criteria of land suitability for red pepper using soil morphological and physical properties. The investigation was carried out in Jechen, Goesan, Euiseong, Andong, Gochang and Pyongchang district in Korea. The obtained results showed that factors related to the decision criteria of the land suitability for red pepper cultivation were soil texture, soil drainage class, land slope, available soil depth and stone content. The criteria of the best suitable soil for red pepper was coarse loamy, well drainage class, C-slope (7-15%), 10-20% gravel content and available soil depth deeper than 100 cm. Also in the best suitable soil, hardpan was located below 100 cm from the soil surface. Outbreak rate of phytophthora blight occurred well in the soils with high clay content, poor drainage class, low land slope and low gravel content. Database determining the decision criteria of the land suitability for red pepper in Jinchen-gun was established by Arc info GIS tool.

• 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.