• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.282-291
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• 2005

사암 및 이암을 기반암으로 하는 산악지역에 건설되는 2-아치 (2-arch) 터널의 거동을 터널설계 단계에서 분석하기 위하여 대규모 실내 모형실험을 실시하였다. 터널이 시공될 예정인 지반과 유사한 지질공학적 특성을 가지는 콘크리트 블록을 이용하여 모형지반을 조성하였다. 모형실험은 중앙터널 (pilot tunnel) 굴착을 포함한 여러 단계의 굴착과정으로 구분하여 실시되었다. 또한 터널 .공용기간 중 터널의 거동을 연구하기 위하여 터널굴착 완료 후 상재하중을 작용시켰다. 실험결과에 의하면 대부분의 지반변위는 중앙터널 굴착에 의해 발생했으며, 그 이후 터널 굴착단계에서의 변위발생은 미미한 것으로 나타났다. 또한 대부분의 지중변위는 0.25D 이내의 범위에서 발생하였다. 여기서 D 는 터널의 폭이다. 한편 실험결과를 분석하여 경암에 시공되는 2-아치 터널의 중앙벽체(centre pillar)에 작용하는 하중에 대한 경험적인 공식을 제시하였다. 터널시공 완료 후 공용기간 중 상재하중이 작용할 경우 그 크기에 따라서는 터널굴착에 의해 발생한 것보다 더 큰 지중변위가 발생할 수 있는 것으로 분석되었다. 터널의 거동은 중앙벽체의 강성에 큰 영향을 받는 것으로 나타나 이를 터널설계에 반영하여 중앙벽체의 강성을 증가시켰다. 현재 터널시공을 위한 사전작업이 진행 중에 있으며, 터널의 굴착은 2005년 하반기에 실시될 예정이다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.3
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• pp.289-300
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• 2013

This study numerically considered the characteristic of smoke movement and the effect of hot smoke gas on tunnel wall surface temperature during road tunnel fire under boundary condition of fire growth curve that is applied to fire analysis in road tunnels. The maximum heat release rate were 20 MW and 100 MW and tunnel air velocities were 2.5 m/s and velocity induced by thermal buoyancy respectively, also the cooling effect of tunnel wall was considered. As results, when tunnel air velocity was constant at 2.5 m/s during tunnel fire, due to the cooling effect of tunnel wall, the smoke layer was rapidly descent after some distance and it flowed the same patterns at the downstream. When heat release rate was 100 MW (and jet fan was not installed), the maximum temperature of tunnel wall surface has risen up to $615^{\circ}C$. The heat transfer coefficient of tunnel wall surface was varied from 13 to $23W/m^2^{\circ}C$ approximately.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.613-621
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• 2015

The most urgent measure to be taken for a rapid rescue when a building collapse happens is to designate or predict a possible location where human beings are alive. It is, however, very difficult to find and correctly designate such cavities by conventional geophysical survey due to a pile of debris of building members. In this study, the simulation of building collapse induced by an earthquake was conducted to predict forming pattern of a existing cavities. The simulation cases included the influence of structure wall existence and height of building. Three types of building structure: five-story, ten-story and fifteen-story were prepared as a simulation case. In the case of high building, a collapse range on the inside of the building increased consequently lowering the possibility of lifeguard cavern forming. In addition, when a wall exists in the basement floor, the possibility that existing cavities could be formed increased compared to the cases without wall.

• Magazine of the Korea Concrete Institute
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• v.28 no.6
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• pp.53-56
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• 2016

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.637-640
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• 2008

Since the first underground LNG tank was constructed in Incheon, continuously many LNG tanks were constructed in Tongyoung and Pyongtaek. The storage capacity of LNG tank increased by 200,000kl and the structure size and the concrete mixing design has changed. The crack of concrete induced by the heat of hydration is a serious problem, particularly in massive concrete structures. In order to control the thermal crack of massive concrete, the low heat portland cement(type Ⅳ) is applied to bottom annular part, bottom central part, lower walls and ring beam. In this study, in order to thermal crack control about the LNG tank wall(lot 8 of #16 Pyongtaek LNG tank) in winter, analysed the concrete temperature, the extention of term, the curing condition and the concrete mixing design. When the concrete mixing design is changed from OPC+FA25% to LHC+FA25%, the thermal crack index is 1.33 and satisfied with construction specifications(over 1.2).

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.179-193
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• 2002

Waste foundry sands were tested to determine their leaching characteristics when used as reactive media in permeable reactive barriers (PRBs). Water leach tests and column leach tests were performed on twelve foundry sands and three reference materials such as Peerless iron, a local fill material, and torpedo sand. The latter three materials were tested to compare concentrations of heavy metals and anions found in other materials commonly placed below the groundwater table with those from the foundry sands. Results of water leach tests md total elemental analyses showed that all of the laundry sands are Category 2 materials per Section NR 538 of the Wisconsin Administrator Code. However, tests on Peerless iron, torpedo sand, and a typical fill material indicate that these materials, which are commonly placed below the groundwater table, also are Category 2 materials. Thus, using foundry sand as a PR3 medium should pose no greater risk than that imposed using conventional construction materials.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.3
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• pp.593-608
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• 2018

If a problem occurs in the strut during the construction of the braced wall, they may cause excessive deformation of the braced wall. Therefore, in this study, the behavior of the braced wall and existing tunnel adjacent to excavation were investigated assuming that the support function of strut is lost during construction process. For this purpose, a series of model test was performed. As a result of the study, the earth pressure in the ground behind wall was rearranged due to the deformation of the braced wall, and the ground displacements caused the deformation of adjacent tunnels. When the struts located on the nearest side wall from the tunnel were removed, the deformation of the braced wall and the tunnel deformation were the largest. The magnitude of transferred earth pressure depended on the location of tunnel. The increase of the cover depth of tunnel from 0.65D to 2.65D caused the increase of the earth pressure by 25.6%. As the distance between braced wall and tunnel was increased from 0.5D to 1.0D, the transferred earth pressure increased by 16% on average. Horizontal displacements of braced wall by the removal of the strut tended to concentrate around the removed struts, and the horizontal displacement increased as the strut removal position is lowered. The tunnel displacement was maximum, when the cover depth of tunnel was 1.15D and the horizontal distance between braced wall and the side of tunnel was 0.5D. The minimal displacement occurred, when the cover depth of tunnel was 2.65D and the horizontal distance between braced wall and the side of tunnel was 1.0D. The difference between the maximum displacement and the minimum displacement was about 2 times, and the displacement was considered to be the largest when it was in the range of 1.15D to 1.65D and the horizontal distance of 0.5D.

• Journal of the Korean Geotechnical Society
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• v.35 no.3
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• pp.5-16
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• 2019

With the recent concentration of urban populations, the constructions of large structures are increasing, along with the development of foundations for large structures. PHC Piles have been used in many structures ever since Japanese introduced the technology at the end of the 20th century. Recently, many studies on the use of the PHC Pile have been carried out as earth retaining using the merits of PHC piles. In this study, static axial compression tests were conducted on the PHC-W piles constructed as column-type in building underground additional wall using the PHC-W earth retaining wall. The end bearing capacity of pile was calculated using the axial load transfer measurement that was obtained from the static axial compression test result. Since end bearing capacity of the PHC-W pile embedded in weathered rock showed a different behaviour from the conventional PHC pile, the calculation method of end bearing capacity for column-type PHC-W piles would be proposed. The unit ultimate end bearing equation proposed for single and group PHC-W pile embedded in weathered rock is $q_b=13.3N_b$ and $q_b=6.8N_b$.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.369-377
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• 2010

Applied to the braced wall in order to stabilize the adjacent tunnel. A pre-load of bracing was imposed to prevent the horizontal displacement of the braced wall during the ground excavation. For this purpose, real scale model tests were conducted, without and with pre-load on braced wall. Real scale model tests were conducted, without and with building load (0 m, 1D, 2D) on ground surface. As a result, it was found that the stability of the existing tunnel adjacent to the braced wall could be greatly enhanced when the horizontal displacement of the braced wall was reduced by applying a pre-load, which was larger than the designated axial force of bracing. In this paper, the behaviors of braced wall and adjacent tunnel was studied. Model tests in 1:10 scale were performed in real construction sequences. Adjacent tunnel was 12 m in diameter and the size of test pit was 2.0 m (width) ${\times}$ 6.0 m (height) ${\times}$ 4.0 m (length) in dimension.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.639-655
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• 2023

Recently, there has been a growing demand for underground space, leading to the utilization of earth retaining walls for deep excavations. Earth retaining walls are structures that are susceptible to displacement, and their measurement and management are carried out in accordance with the standards established by the Ministry of Land, Infrastructure, and Transport. However, managing displacement through measurement can be considered similar to post-processing. Therefore, in this study, we not only predicted the horizontal displacement of a retaining wall with ground anchors installed using machine learning, but also analyzed the impact of the prediction model based on data scaling and data splitting methods while learning measurement data using machine learning. Custom splitting was the most suitable method for learning and outputting measurement data. Data scaling demonstrated excellent performance, with an error within 1 and an R-squared value of 0.77 when the anchor tensile force and water pressure were standardized. Additionally, it predicted a negative displacement compared to a model that without scaling.