• 한국터널지하공간학회 논문집
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• 제4권4호
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• pp.287-300
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• 2002

터널굴착 발파기술로 새로 개발된 Composition Presplitting Angle Cut (COPA)은 기존 공법과는 달리 심발부에 먼저 인장파괴를 통하여 선균열 (사전절단)을 형성시킨다. 본 연구에서는 선균열 효과를 검증하기 위하여 굴진효율과 소음 진동의 발생크기를 측정하는 현장시험을 실시하였다. 그리고 이 공법의 경제성 및 작업성 (시공성)을 비교하기 위하여 동일한 조건에서 기존의 발파공법을 동시에 시험하여 그 결과를 비교하였다. 시험 결과 COPA - Cut 발파공법이 기존 발파공법보다 굴진효율이 증가하고 소음 진동이 감소되었다. 또한 경제성, 시공성 및 품질관리 측면에서 우수하다는 것을 확인 되었다.

• 한국터널지하공간학회 논문집
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• 제14권3호
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• pp.197-213
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• 2012

디스크커터는 암석의 절삭을 위해 TBM에 사용되는 핵심 굴착도구이다. 본 연구에서는 디스크커터에 의한 암석의 절삭 시에 커터 링에 발생하는 변형특성을 파악하기 위하여, 경암에 대한 선형절삭실험 시에 커터 링에 부착한 일련의 변형률게이지와 적외선 열화상 카메라에 의한 계측을 실시하였다. 실험결과, 커터 링은 매우 뚜렷한 선형탄성 거동을 보였으며, 암석 절삭에 의한 커터 링의 온도 상승은 $14.4^{\circ}C$ 이내로 나타났다. 따라서 본 연구에서 수행한 선형절삭실험 조건에서는 절삭으로 인한 커터 링의 변형과 온도상승이 크지 않았음을 알 수 있었다.

• 한국농촌건축학회논문집
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• 제14권1호
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• pp.37-44
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• 2012

This study is to propose development direction of sang-dang mountain fortress toward the utilization of historical and cultural heritage as tourist attraction through the consideration of problems on sang-dang mountain fortress development. First of all, the historical significance, development project and status of Sang-dang mountain fortress was figured out. Furthermore, using pattern and general user's view was understood through the questionnaire survey then research on the actual condition of traditional korean village was performed. The ongoing development project focusing on restoration of cultural properties to its original state through an archaeological excavation investigation turned out to be lack of consideration on the utilization of sang-dang mountain fortress such as tourists inducement. Furthermore, the measures on traditional korean village which has been a problem by forming commercial area recklessly have been left off. Therefore, additional development plan is required on convenient and amenity facilities and rest places for visitors including environment improvement of traditional korean village based on the development for the restoration of cultural properties to its original state.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.821-832
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• 2008

The hazard warning levels are necessary for the rational design and safety construction of underground space, as mountain and urban tunnel. Sakurai provided the hazard warning levels for assessing the stability of tunnels using the critical strain of rock mass, which is defined as a ratio between uni-axial compressive strength and the Young's modulus. The concept of critical strain guidelines is introduced in this study for the assessment of tunnel safety during excavation. Moreover, in this paper, the critical strain properties of sedimentary rock in Korea has investigated and analysed in detail by Lab. test, as the uniaxial and triaxial compression tests. Finally, critical strain properties of sedimentary rock on uniaxial and triaxial stress condition is discussed the relationship of failure strain values, uniaxial and triaxial compression strengths, confining pressure and Young's modulus.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.939-948
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• 2006

The structural anisotropy and heterogeneity of rock mass, caused by discontinuities and weak zones, have a great influence on the deformation behavior of tunnel. Tunnel construction in these complex ground conditions is very difficult. No matter how excellent a geological investigation is, local uncertainties of rock mass conditions still remain. Under these uncertain circumstances, an accurate forecast of the ground conditions ahead of the advancing tunnel face is indispensable to safe and economic tunnel construction. This paper presents the effect of anisotropy and heterogeneity of the rock masses to be excavated by numerical analysis. The influences of distance from weak zone, the size or dimension, the different stiffness and the orientation of weak zones are analysedby 2-D and 3-D finite element analysis. By analysing these numerical results, the tunnel behavior due to excavation can be well understood and the prediction of rock mass condition ahead of tunnel face can be possible.

• 한국터널지하공간학회 논문집
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• 제8권4호
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• pp.345-354
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• 2006

막장볼트는 시공중 지반조건 및 천공기계의 기계적 원인에 의해 수평으로부터 벗어나게 타설되는 경우가 많다. 본 연구는 실내실험과 수치해석을 통하여 막장볼트가 수평으로부터 벗어나는 경우에 대한 보강효과의 변화를 검증하였다. 또한 이 결과를 바탕으로 추가해 주어야 하는 볼트의 개수에 대하여 고찰하였다. 본 연구로부터 막장 중앙부부터 타설하는 막장볼트는 가능한 한 수평으로 타설하는 것이 효과적이며 벗어나는 경우에는 볼트를 추가해 주어야 하는 것이 명확해 졌다. 본 연구의 조건하에서는3본/단면을 타설 할 경우 모든 볼트가 $R15^{\circ}$로 수평으로부터 벗어나면 1.5본/단면을 추가해 주어야 하는 것으로 나타났다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.375-378
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• 2007

The selection of the support system is an important design parameter in design and construction of the tunnel using the new Australian tunnel method. It is a common practice to select the support based on the rock mass grade, in which the rock mass is classified into five rock groups. The method is applicable if the characteristics of the rock mass are uniform in the direction of tunnel excavation. However, such case is seldom encountered in practice and not applicable when the properties vary along the longitudinal direction. This study performs comprehensive three dimensional finite difference analyses to investigate the ground deformation pattern for cases in which the rock mass properties change in the direction of the tunnel axis. The numerically calculated displacements at the tunnel crown show that the displacement is highly dependent on the stiffness contrast of the rock masses. The results strongly indicate the need to select the support type $0.5\sim1.0D$ before the rock mass boundary. The paper proposes a new guideline for selecting the support type based the results of the analyses.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.214-220
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• 2003

Pipe jacking is a name for a method to excavate a tunnel by pushing pipe into the ground from an especial pit. Size of tunnels in this method is different from under 900mm (microtunneling) to more than 3,000mm. Method of excavation is also different from hand digging to use of any kind of tunnel boring machines such as slurry and earth pressure balance (EPB) machines. Slurry pipe jacking was firmly established as a special method for the nondisruptive construction of the underground tunnels in urban area. During the pipe jacking and microtunneling process, the jacking load is an important parameter, controlling the pipe wall thickness, need to and location of intermediate jacking station, selection of jacking frame and lubrication requirements. The main component of the jacking load is due to frictional resistance. In this paper the skin friction between pipe surface and surrounding condition also lubricant quality based on a few fundamental tests, were considered. During this study unconfined compressive strength test, dynamic friction measurement test and direct shear box test were raised for one of the largest diameter slurry pipe jacking project in Fujisawa city in Japan. It could be concluded that in slurry pipe jacking, prediction of frictional forces are mainly dependent on successful lubrication, its quality and lubricant strength parameters. Conclusions from this study can be used for the same experiences.

• Journal of the Korean Wood Science and Technology
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• 제27권4호
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• pp.15-19
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• 1999

Three wood coffins of Chosun Dynasty period buried about 450 years ago were excavated in the sound condition in Andong area in the early 1998. The proprietors of wood coffins were grandparents, Mr. Myoung Jong Lee and Mrs. Mun, and their grandson, Mr. Eung Tae Lee, and the social standing of their family was known to belong to the nobility in those days by the clan genealogy. All the wood coffins investigated through light microscopy had same anatomical characteristics as follows: abrupt to somewhat abrupt tracheid transition from earlywood to latewood; normal longitudinal and horizontal resin canals with thin-walled epithelium; tylosoids in resin canals; bordered pits frequently in 1 row on radial walls of tracheids; 1 or 2 window-like pits per cross-field; uniseriate and fusiform rays; heterogeneous rays composed of body ray parenchyma cells and marginal ray tracheids or homgeneous rays composed of only ray tracheids; dentate ray tracheids; occasional trabeculae traversing tracheids in radial direction. Based on theses microscopic characteristics, all the wood coffins were identified to be Korean red pine (Pinus densiflora) or Korean black pine (Pinus thunbergii). Korean black pine growing naturally in coastal area might not be probable because the site of excavation, Andong area, was mountainous and inland area of Korea Thus, Korean red pine was thought to be the possible species for the wood coffins because of its natural distribution through the Korean Peninsula and the easy availability.

• Geomechanics and Engineering
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• 제20권6호
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• pp.517-525
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• 2020

The long-term stability of rock engineering is significantly affected by the time-dependent deformation behavior of rock, which is an important mechanical property of rock for engineering design. Although the hard rocks show small creep deformation, it cannot be ignored under high-stress condition during deep excavation. The inner mechanism of creep is complicated, therefore, it is necessary to investigate the relationship between microscopic creep mechanism and the macro creep behavior of rock. Microscopic numerical modeling of sandstone creep was performed in the investigation. A numerical sandstone sample was generated and Parallel Bond contact and Burger's contact model were assigned to the contacts between particles in DEM simulation. Sensitivity analysis of the microscopic creep parameters was conducted to explore how microscopic parameters affect the macroscopic creep deformation. The results show that the microscopic creep parameters have linear correlations with the corresponding macroscopic creep parameters, whereas the friction coefficient shows power function with peak strength and Young's modulus, respectively. Moreover, the microscopic parameters were calibrated. The creep modeling curve is in good agreement with the verification test result. Finally, the creep curves under one-step loading and multi-step loading were compared. This investigation can act as a helpful reference for modeling rock creep behavior from a microscopic mechanism perspective.