• 한국터널공학회:학술대회논문집
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• 한국터널공학회 2005년도 학술발표회 논문집
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• pp.233-247
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• 2005

Most tunnel lining material which has been used in the domestic is a concrete. But many problems as the construction period, the cost, and the crack occurrence for the design, construction, and management were happened in the concrete lining. For this reason, many research institutes like the Korea Highway Corporation recognize the necessity of an alternate material development and grow on the interest for that. So in this study, the seismic behaviour characteristics for the application of the Corrugated Steel Plate Lining in cut-and-cover tunnel are evaluated as several conditions for the backfill height, the cutting slope, and the relative density of backfill soil are changed. The compressive stress which is calculated in the Corrugated Steel Plate Lining by the seismic load is decreased as the backfill height increases and the cut slope grows gentle. Also, the moment shows the tendency of decrease according to the increase of the backfill height. But in the case of the relative density of the backfill soil is small, the moment increases according to the increase of the backfill height and affects the dynamic behaviour characteristic. So it is considered that the relative density of the backfill soil is also the important point. As the result in analyzing the seismic response characteristics of the reinforcement spacing of the Corrugated Steel Plate, the variation in the compressive force is hardly happened, but the moment and the shear force increase on the reinforcement spacing being narrow.

• 한국지반환경공학회 논문집
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• 제15권12호
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• pp.117-128
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• 2014

일반적으로 기존 터널이나 공동 등에 근접하여 터널을 시공하는 경우에 기존 공동과 터널간의 간섭이 발생하며 이로 인한 영향을 최소화하기 위하여 이격거리를 터널의 폭 이상으로 유지하도록 일부시방서 등에 권고안이 제시되어 있는 상태이다. 이와같이 공동이나 구조물 등에 근접한 터널은 지반 상태 및 공동의 크기, 보조공법 등을 고려하여 결정하여야 하며, 지반이 연약한 상태에서는 근접도에 따라 민감한 반응을 나타내고 변형량도 크게 나타나므로 지반조건을 고려한 터널계획이 이루어져야 한다. 설계단계에서 공동이 터널의 안정성에 미치는 영향을 검토하기 위해 현장측정, 수치해석, 모형시험 등의 방법이 고려될 수 있으며, 이 중에서 모형시험(Scaled model test)은 결과를 가시적으로 나타낼 수 있을 뿐 아니라, 수치해석과 비교를 통해 거동을 보다 상세하고 현실적으로 예측 가능하다는 장점이 있다. 본 연구에서는 공동에 인접하여 터널 굴착이 이루어지는 경우, 계획단계에서 실제 거동을 예측하기 위한 모형시험 방법과 시험 시 고려사항들에 대해 고찰하고 실제 시험 결과와 수치해석 결과의 비교를 통해 제안된 기법의 적정성을 평가하였다. 또한 터널 굴착 시 터널 주변에 분포하는 공동의 이격거리에 따른 영향이 적절히 반영되는지 여부를 파악하기 위해 공동과 터널간 이격거리를 0.25D, 0.50D, 1.00D, Network 상태 분포 시로 가정한 일련의 모형시험을 수행하였으며, 공동이 없는 조건과 비교하여 제안된 방법의 적정성을 확인하였다. 추가적으로 축소모형시험 결과의 타당성 검증을 위한 목적으로 시험조건을 반영한 수치해석을 수행하였으며, 수치해석 결과와 모형시험 결과의 비교 검증을 수행하였다. 모형시험 및 수치해석 결과 이격거리 1.0D는 공동과 터널이 독립적인 거동을 보이는 한계거리로 평가되었다.

• Geomechanics and Engineering
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• 제29권3호
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• pp.301-310
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• 2022

Accurate prediction of mixed ground conditions ahead of a tunnel face is of vital importance for safe excavation using tunnel boring machines (TBMs). Previous studies have primarily focused on electrical resistivity surveys from the ground surface for geotechnical investigation. In this study, an FE (finite element) numerical model was developed to simulate electrical resistivity surveys for the prediction of risky mixed ground conditions in front of a tunnel face. The proposed FE model is validated by comparing with the apparent electrical resistivity values obtained from the analytical solution corresponding to a vertical fault on the ground surface (i.e., a simplified model). A series of parametric studies was performed with the FE model to analyze the effect of geological and sensor geometric conditions on the electrical resistivity survey. The parametric study revealed that the interface slope between two different ground formations affects the electrical resistivity measurements during TBM excavation. In addition, a large difference in electrical resistivity between two different ground formations represented the dramatic effect of the mixed ground conditions on the electrical resistivity values. The parametric studies of the electrode array showed that the proper selection of the electrode spacing and the location of the electrode array on the tunnel face of TBM is very important. Thus, it is concluded that the developed FE numerical model can successfully predict the presence of a mixed ground zone, which enables optimal management of potential risks.

• Wind and Structures
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• 제18권5호
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• pp.511-528
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• 2014

The characteristics of wake galloping phenomenon for two parallel/unparallel circular cylinders were investigated via wind tunnel tests. The two cylinders were initially deployed in parallel and wake galloping phenomena were observed by varying the center-to-center distance. The effect of an unparallel arrangement of two cylinders was next investigated by fixing the spacing ratio of one side of the cylinders at 5.0D and the other side at 3.0D, in which D represents the diameter of the cylinder. For the unparallel disposition, the 5.0D side showed a small, limited vibration while the 3.0D side produced much larger amplitude of vibration, resulting in a rolling motion. However, the overall amplitude appeared to decrease in unparallel disposition when compared with the amplitude of the 3.0D - 3.0D parallel case. This represents the mitigation effect of wake galloping due to the unparallel disposition between two cylinders. Flow visualization tests with particle image velocimetry were conducted to identify flow fields between two cylinders. The test results demonstrate the existence of a complex interaction of the downstream cylinder with the shear layer generated by the upstream cylinder. When the spacing ratio was large enough, the shear layer was not observed and the downstream cylinder showed only limited random vibration.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.270-275
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• 2003

고준위 폐기물 처분용기 개념설계의 일부분으로 열전달 해석을 수행하였다. 현재까지 진행된 처분개념인 지하 500m 암반 내 처분공에 4개의 PWR 사용후 핵연료 다발을 처분용기에 넣어 처분하였을 경우에 대해 온도 분포를 구하였다. 열전달 해석에는 유한요소법을 이용하는 NISA 프로그램을 이용하였다. 처분용기 내 핵연료의 열 발생에 의한 $\ulcorner$처분용기＋벤토나이트 버퍼＋처분터널＋암반$\lrcorner$ 복합시스템의 온도분포를 구하였다. 처분터널 사이의 간격이 40m 처분공 사이의 간격이 6m인 경우 처분용기 외곽 쉘과 완충재 사이의 온도는 처분 후 15-16년에 도달할 때 최대 $87.5^{\circ}C$까지 증가하다가 서서히 감소하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1487-1501
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• 2011

Recently, fast-growing up railway transportations. Because, regional traffic congestion problem solving and a period of rapid expansion to meet the demand of industries. In addition the government also suggest to new paradigm for the future 'Low Carbon, Green Growth' is presented as a new national vision. To meet the social needs and the time demands, Last of the railway increase very long tunnels and huge deep tunnels. Especially this trend accelerated high speed up in the tunnel, the revision of design criteria and research challenges are being actively improved. Mainly in the tunnel cross-section was under the control of the vehicle train speed 150km/hr by the construction of the vehicle cross-section of the tunnel. More than 200km/hr rail tunnel depending on the vehicle's speed caused the tunnel to the pressure fluctuations will be governed by the aerodynamic changes. Considering the economy to ensure the optimum cross-section of the railway tunnel to the description scheme is selected cross-section of the railway tunnel to determine the size domestic or international railway tunnel for the elements((based on fast Algorithm design criteria, the center line spacing, streetcar line, cross-sectional shape, sectoral issues, such as interface and aerodynamics) based on design practices and to review results. In this study, to propose guidelines depending on the size of a railway tunnel cross section for the size of the determining reasonable factors when designing the railway tunnel and cost-effective standards guidelines.

• 터널과지하공간
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• 제2권2호
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• pp.212-223
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• 1992

The distinct element method(DEM) si well suited to the kinematic analysis of blocky rock masses. Two distinctive problems, a rock avalache and tunnel in jointed rock masses, are chosen to apply the DEM which is based on perfectly rigid behaviour of blocks. Investigated for both problems are the effects of the input parameters such as contact stiffnesses, friction coefficient and damping property. Using various types of models of the avalanche and tunne, an extensive parametric study is done to gain experiences in the method, and then to alleviate difficulties in determining parameter values suitable for a given problem. The coefficient of frictio has significant effects on all aspects of avalanche motion(travel distance, velocity and travel time), while the stiffnesses affect the rebounding and jumping motions after collision. The motion predicted by the models having single and mutiple blocks agrees well to the observations reported on the actual avalache. For the tunnel problem, the behaviour of the key block in an example tunnel is compared by testing values of the input parameters. The stability of the tunnel is dependent primarily on the friction coefficient, while the stiffness and damping properties influence the block velocity. The kinematic stability of a tunnel for underground unclear waste repository is analyzed using the joint geometry data(orientation, spacing and persistence) occurred in a tailrace tunnel. Allowing a small deviation to the mean orientation results in different modes of failure of the rock blocks around the tunnel. Of all parameters tested, the most important to the stability of the tunnel in blocky rock masses are the geometry of the blocks generated by mapping the joint and tunnel surfaces in 3-dimensions and also the friction coefficient of the joints particularly for the stability of the side walls.

• 대한기계학회논문집B
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• 제31권8호
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• pp.680-687
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• 2007

The paper presents a numerical simulation of flow of a turbulent boundary layer, representing a typical wind environment and matching a series of wind tunnel observations. The simulations are carried out at a Reynolds number of 20,000, based on the velocity U at a pseudo-height h, and large enough that the flow be effectively Reynolds number independent. Some wall models are proposed for the LES(Large Eddy Simulation) of the turbulent boundary layer over a rough surface. The Jenson number, $J=h/z_0$, based on the roughness length $z_0$, is 600 to match the wind tunnel data. The computational mesh is uniform with a spacing of h/32, as this aids rapid convergence of the multigrid solver, and the governing equations are discretised using second order finite differences within a parallel multiblock environment. The results presented include the comparison between wind tunnel measurements and LES computations of the turbulent boundary layer over rough surface.

• 한국지반공학회논문집
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• 제30권9호
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• pp.41-55
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• 2014

일반적으로 암반 터널 지진해석 시 절리의 영향을 무시하며 암반을 연속체라 가정한다. 하지만 이와 같은 가정의 적절성에 관해서는 연구된 바 없다. 본 연구에서는 응답변위법을 적용하여 지진동에 의하여 유발되는 암반 절리의 변위가 터널의 응답에 미치는 영향을 일련의 개별요소법을 이용하여 수치적으로 규명하였다. 해석에는 절리와 터널의 교차위치, 절리의 강성, 경사, 간격, 그리고 암반과 터널 사이의 인터페이스 강성이 고려되었다. 해석 결과, 절리의 강성이 터널에 가장 지배적인 영향을 미치는 것으로 나타났다. 절리의 간격은 클수록 변위가 국부적으로 집중되어 응답이 증가하는 것으로 나타났다. 절리의 경사는 정적인 경우와는 상반되게 $45^{\circ}$에서 응답이 가장 작게 계산되었다. 이는 전단변형으로 인하여 수직면과 수평면에 큰 전단응력이 작용하여 주응력면이 $45^{\circ}$로 회전하기 때문인 것으로 판단된다. 결과적으로 절리의 경사, 간격, 강성 모두 터널의 응답에 큰 영향을 미치며 특히 간격이 큰 미끈한 수직 또는 수평방향 절리가 터널을 통과하는 경우가 가장 위험한 것으로 나타났다. 또한 터널 라이닝에는 휨응력보다는 전단응력이 큰 폭으로 증가하므로 내진설계 시 이를 반드시 검토해야 할 것으로 판단된다.

• Wind and Structures
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• 제16권3호
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• pp.249-261
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• 2013

Flexible stay cables on cable-stayed bridges are three-dimensional. They sag and flex in the complex wind environment, which is a different situation to ideal rigid cylinders in two-dimensional wind flow. Aerodynamic interference and the response characteristics of wake galloping of full-scale parallel cables are potentially different due to three-dimensional flows around cables. This study presents a comprehensive wind tunnel investigation of wake galloping of parallel stay cables using three-dimensional aeroelastic cable models. The wind tunnel study focuses on the large spacing instability range, addressing the effects of cable separation, wind yaw angle, and wind angle of attack on wake galloping response. To investigate the effectiveness of vibration suppression measures, wind tunnel studies on the transversely connected cable systems for two types of connections (flexibility and rigidity) at two positions (mid-span and quarter-span) were also conducted. This experimental study provides useful insights for better understanding the characteristics of wake galloping that will help in establishing a guideline for the wind-resistant design of the cable system on cable-stayed bridges.