• 한국강구조학회 논문집
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• 제24권1호
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• pp.47-58
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• 2012

본 연구에서는 터널 내 통과차량에 의하여 발생하는 풍하중으로 인한 터널라이닝의 동적거동에 대하여 분석하였다. 차량으로 인한 풍하중은 목표지점을 지나가는 차량에 대하여 압력과 팽창을 나타내는 시간함수를 이용하여 모형화 하였으며, 파형강판으로 이루어진 터널라이닝은 3차원 쉘 요소를 사용하였다. 쉘 요소로 모델링된 3차원 터널라이닝의 동적해석은 많은 양의 메모리와 시간이 요구되지만 파형강판의 동적특성을 반영하는 한편 최대한 단순화된 모형을 제시하여 해석에 이용하였다. 터널라이닝의 변위를 분석하기 위해 다양한 차량 주행 조건 및 맞바람 풍속이 고려되었다. 차량과 풍속이 증가하면 응답 또한 증가하였으며, 최대변위는 차량이 120km/h로 교차주행 시 25mm로 나타났다. 연속주행 시 응답에 미치는 영향은 단독주행 응답보다 2.5% 이내로 크지 않게 나타났다. 따라서 숏크리트가 적용되지 않는 독립구조체 터널라이닝의 경우동적거동은 반드시 고려해야하는 것으로 판단된다.

• Geomechanics and Engineering
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• 제29권5호
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• pp.567-582
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• 2022

In the present study, a series of physical experiments and numerical simulations were conducted to investigate the effects of mode I and mixed-mode I/II cracks on the fracture modes and stability of roadway tunnel models. The experiments and simulations incorporated different inclination angle flaws under both static and dynamic loads. The quasi-static and dynamic testing were conducted by using an electro-hydraulic servo control device and drop weight impact system (DWIS), and the failure process was simulated by using rock failure process analysis (RFPA) and AUTODYN software. The stress intensity factor was also calculated to evaluate the stability of the flawed roadway tunnel models by using ABAQUS software. According to comparisons between the test and numerical results, it is observed that for flawed roadways with a single radical crack and inclination angle of 45°, the static and dynamic stability are the lowest relative to other angles of fractured rock masses. For mixed-mode I/II cracks in flawed roadway tunnel models under dynamic loading, a wing crack is produced and the pre-existing cracks increase the stress concentration factor in the right part of the specimen, but this factor will not be larger than the maximum principal stress region in the roadway tunnel models. Additionally, damage to the sidewalls will be involved in the flawed roadway tunnel models under static loads.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.89-96
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• 2001

A concrete lining of NATM tunnel is the final product of a process that involves planning and evaluation of user needs, geotechnical investigations, analysis of ground-lining interaction, construction, and observations and modifications during construction. The designer must consider the lining in context of the many function, construction, and geotechnical requirements. Also, the loss of supporting capacity of shotcrete lining due to poor rock qualities and shotcrete erosion must be considered. The values, shapes, and estimating methods of rock load and water pressure are very different with every designers. Estimating methods of rock loads used in the design of NATM tunnel concrete lining are investigated. Numerical analyses are done in various conditions. And the rock loads estimated from radial stress and plastic zone are compared respectively.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.739-744
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• 2007

Wind loads for cladding can be estimated using the maximum wind pressure including gust effects from wind-tunnel tests. However, when estimating the maximum wind pressure with gust effects, wind pressure coefficients for cladding would be different according to the averaging time of wind pressures, In the paper, for wind pressures obtained from wind-tunnel tests for apartment buildings, whose window panes were damaged by actual strong wind, it was investigated how pressure coefficients varied according to the size of cladding and averaging time using TVL method of Lawson. In result, it was found that the lesser the size of cladding and averaging time were, the larger pressure coefficients became. Accordingly, to estimate wind loads for cladding of apartment buildings and design it, the averaging time of wind pressures should be considered properly.

• Wind and Structures
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• 제21권4호
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• pp.425-442
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• 2015

This paper discusses the processing of the wind loads measured in wind tunnel tests by means of multi-channel pressure scanners, in order to compute the response of 3D structures to atmospheric turbulence in the time domain. Data compression and the resulting computational savings are still a challenge in industrial contexts due to the multiple trial configurations during the construction stages. The advantage and robustness of the bi-orthogonal decomposition (BOD) is demonstrated through an example, a sail glass of the Fondation Louis Vuitton, independently from any tentative physical interpretation of the spatio-temporal decomposition terms. We show however that the energy criterion for the BOD has to be more rigorous than commonly admitted. We find a level of 99.95 % to be necessary in order to recover the extreme values of the loads. Moreover, frequency limitations of wind tunnel experiments are sometimes encountered in passing from the scaled model to the full scale structure. These can be alleviated using a spectral extension of the temporal function terms of the BOD.

• 지질공학
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• 제22권3호
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• pp.323-330
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• 2012

국내 터널현장에서는 기존 H형 강지보를 대체하는 격자지보의 사용이 급격히 증가되고 있다. 터널에 작용하는 지반하중은 숏크리트와 격자지보에 의하여 지지된다. 따라서 터널의 안정성을 평가하기 위해서는 격자지보에 대한 계측이 필수적이다. 그러나 현재까지 국내에서는 격자지보에 대한 계측이 거의 수행되지 않았으며 적절한 계측 방법도 확립 되지 못한 상태이다. 본 연구에서는 격자지보용 로드셀을 이용한 신뢰성 있는 격자지보 계측 방법을 제안하였다. 또한 시공 중인 터널현장에서 격자지보 계측을 수행하여 격자지보에 작용하는 지반하중을 제시하였다.

• Structural Engineering and Mechanics
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• 제58권6호
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• pp.967-988
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• 2016

Due to the significant aerodynamic interference from sub-towers and surrounding tall buildings, the wind loads and dynamic responses on main tower of three-tower connected tall building typically change especially compared with those on the isolated single tall building. This paper addresses the wind load effects and equivalent static wind loads (ESWLs) of three-tower connected tall building based on measured synchronous surface pressures in a wind tunnel. The variations of the global shape coefficients and extremum wind loads of main tower structure with or without interference effect under different wind directions are studied, pointing out the deficiency of the traditional wind loads based on the load codes for the three-tower connected tall building. The ESWLs calculation method based on elastic restoring forces is proposed, which completely contains the quasi-static item, inertia item and the coupled effect between them. Then the wind-induced displacement and acceleration responses for main tower of three-tower connected tall building in the horizontal and torsional directions are investigated, subsequently the structural basal and floor ESWLs under different return periods, wind directions and damping ratios are studied. Finally, the action mechanism of interference effect on structural wind effects is investigated. Main conclusions can provide a sientific basis for the wind-resistant design of such three-tower connected tall building.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.5-9
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• 2010

A numerical wind tunnel simulation is performed in order to predict wind loads acting on a building. The aim of the present study is to suggest a guideline for the numerical wind tunnel analysis, which could provide more detail wind load distributions compared to the wind code and expensive wind tunnel experiments. To validate the present numerical simulation, wind-induced loads on a 6 m cube model is predicted. Atmospheric boundary layer is used as a inlet boundary condition. Various effect of numerical methods are investigated such as size of computational domain, grid density, turbulence model and discretization scheme. The appropriate procedure for the numerical wind tunnel analysis is suggested through the present study.

• 한국터널지하공간학회 논문집
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• 제9권1호
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• pp.91-97
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• 2007

절리가 존재하는 암반에서 2-Arch 터널을 굴착할 때 절리방향과 굴착단계에 따른 필라하중의 변화를 실험적으로 연구하였다. 이를 위해, 대형 모형 실험기(폭 3.3m, 높이 3.0m, 길이 0.45m)에 1/10 크기의 2-Arch 모형터널을 갖는 다양한 각도의 절리를 포함한 지반을 조성하고, 실제 시공과정을 따라 굴착하면서 터널굴착으로 인한 터널 주변지반의 변형을 측정하고, 굴착단계에 따라 필라에 작용하는 하중을 측정하였다. 계측된 데이터로부터 2-Arch 터널의 굴착에 따른 거동을 분석한 결과 절리의 각도에 따라 굴착단계별로 터널 주변지반의 변형 및 필라에 작용하는 하중이 크게 영향을 받는 것을 확인하였다.

• Wind and Structures
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• 제32권5호
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• pp.471-485
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• 2021

Onshore wind turbines may experience substantially different wind loads depending on their working conditions, i.e. rotation velocity of rotor blades, incoming freestream wind velocity, pitch angle of rotor blades, and yaw angle of the wind-turbine tower. In the present study, aerodynamic loads acting on a horizontal axis wind turbine were accordingly quantified for the high tip speed ratio (TSR) at high yaw angles because these conditions have previously not been adequately addressed. This was analyzed experimentally on a small-scale wind-turbine model in a boundary layer wind tunnel. The wind-tunnel simulation of the neutrally stratified atmospheric boundary layer (ABL) developing above a flat terrain was generated using the Counihan approach. The ABL was simulated to achieve the conditions of a wind-turbine model operating in similar inflow conditions to those of a prototype wind turbine situated in the lower atmosphere, which is another important aspect of the present work. The ABL and wind-turbine simulation length scale factors were the same (S=300) in order to satisfy the Jensen similarity criterion. Aerodynamic loads experienced by the wind-turbine model subjected to the ABL simulation were studied based on the high frequency force balance (HFFB) measurements. Emphasis was put on the thrust force and the bending moment because these two load components have previously proven to be dominant compared to other load components. The results indicate several important findings. The loads were substantially higher for TSR=10 compared to TSR=5.6. In these conditions, a considerable load reduction was achieved by pitching the rotor blades. For the blade pitch angle at 90°, the loads were ten times lower than the loads of the rotating wind-turbine model. For the blade pitch angle at 12°, the loads were at 50% of the rotating wind-turbine model. The loads were reduced by up to 40% through the yawing of the wind-turbine model, which was observed both for the rotating and the parked wind-turbine model.