• Title/Summary/Keyword: 변위분석

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Prediction of Ground Condition Changes Ahead of Tunnel Face Using Three-Dimensional Absolute Displacement Analysis (터널 3차원 절대변위 해석기법을 이용한 막장전방지반 예측)

  • Bang, Joon-Ho;Han, Il-Young
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.8 no.2
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    • pp.101-113
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    • 2006
  • Arching effect occurs around the unsupported excavation surface near to tunnel face when a tunnel is excavated in a stable rock mass. If a weak fracture zone exists in front of tunnel face, a displacement occurs between tunnel face and weak fracture zone due to stress concentration. If three-dimensional absolute coordinates (longitudinal, transverse, vertical direction) is measured at tunnel face by geodetic method, the ground change in front of the tunnel face can be predicted by analysing three-dimensional absolute displacement. The purpose of this study is to verify the analysis method of three-dimensional absolute displacement by comparing the trend of displacement ratio at crown and sidewall of tunnel and the influence line/trend line of crown settlement compared with TSP results in the same section.

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Comparative Analysis of Fault Prediction with Horizontal and Longitudinal Displacements on Tunnel (터널 굴진면 수평변위와 천단변위를 이용한 단층대 예측방법의 비교·분석)

  • Yun, Hyun-Seok;Seo, Yong-Seok
    • The Journal of Engineering Geology
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    • v.26 no.3
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    • pp.403-411
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    • 2016
  • A three-dimensional finite element analysis was conducted to analyze the predictable distances of a fault zone by using longitudinal displacement on tunnel face, trend line, L/C ratio, and C/C0 ratio at tunnel crown. The analysis used 28 numerical models with various fault attitudes. As a result, those faults that have drives with dip could be predicted earliest in L/C and C/C0 ratio analysis. And those faults that have drives against dip could be predicted earliest in L/C ratio and longitudinal displacement analysis. In addition, the fault zone ahead of tunnel was predicted in most models by using longitudinal displacement, trend line, L/C ratio, and C/C0 ratio. However, the longitudinal displacement among these methods may be most usefully predict a fault zone since it is displacements can be measured immediately after tunnel excavation.

Numerical Investigation of the Radial Convergence of Circular Tunnel Excavated in Rock Mass for Generalized Hoek-Brown (일반화된 Hoek-Brown 암반에 굴착된 원형터널의 내공변위 특성 분석)

  • Lim, Kwang-Ok;Lee, Youn-Kyou
    • Tunnel and Underground Space
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    • v.28 no.1
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    • pp.59-71
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    • 2018
  • Since the generalized Hoek-Brown (GHB) function predicts the strength of the jointed rock mass in a systematic manner by use of GSI index, it is widely used in rock engineering practices. In this study, a series of 2D elasto-plastic FE analysis, which adopts the GHB criterion as a yield function, was carried out to investigate the radial convergence characteristics of circular tunnel excavated in the GHB rock mass. The effect of the plastic potential function on the elasto-plastic displacement was also examined. In the analysis, the wide range of both the $K(={\sigma}_h/{\sigma}_v)$ and GSI values are considered. For each K value, the variation of the ratio of sidewall displacement to roof displacement was calculated with varying GSI values and the obtained displacement patterns were analysed. The calculation results show that the displacement ratio significantly depends not only on the K value but also on the range of GSI value. In particular, for lower range of GSI value, the displacement ratio pattern calculated in the elasto-plastic regime is opposite to that predicted by the elasticity theory. In addition, the variation of the radial displacement ratio with GSI value for different types of plastic potential function showed similar trend.

Evaluation of Inelastic Displacement Ratios for Smooth Hysteretic Behavior Systems (완만한 이력거동 시스템에 대한 비탄성 변위비의 평가)

  • Song, Jong-Keol
    • Journal of the Earthquake Engineering Society of Korea
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    • v.15 no.3
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    • pp.11-26
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    • 2011
  • The inelastic displacement ratio is defined as the ratio of the peak inelastic displacement to the peak linear elastic displacement. The inelastic displacement ratio allows simple evaluation of the peak inelastic displacement directly from the peak elastic displacement without computation of the inelastic response. Existing research of the inelastic displacement ratio is limited to piece-wise linear systems such as bilinear or stiffness degrading systems. In this paper, the inelastic displacement ratio is investigated for smooth hysteretic behavior systems subjected to near- and far-fault earthquakes. A simple formula of the inelastic displacement ratio is proposed by using a two step procedure of regression analysis.

Analysis of Surface Displacement Due to the 2024 Noto Peninsula Earthquake in Japan: Focus on Horizontal Surface Displacement Using Offset Tracking (2024년 일본 노토반도 지진으로 인한 지표 변위 분석: Offset Tracking을 이용한 수평 방향 지표 변위를 중심으로)

  • Bong Chan Kim;Seulki Lee;Chang-Wook Lee
    • Korean Journal of Remote Sensing
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    • v.40 no.3
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    • pp.307-316
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    • 2024
  • On January 1, 2024, an earthquake with a moment magnitude of 7.5 occurred on the Noto Peninsula in Japan. The earthquake caused significant surface displacement on the Noto Peninsula. The surface displacement is measured by global navigation satellite system (GNSS) base stations, but there are limitations in obtaining information in areas where base stations do not exist. Therefore, in this study, we aim to determine the horizontal land surface displacement across the Noto Peninsula using offset tracking, which can detect rapidly occurring displacement. As a result of analyzing the Noto Peninsula using the offset tracking technique, it was found that more horizontal surface displacement occurred in the northwest region than in the northeast region of the Noto Peninsula, where the epicenter was located, and the surface displacement value reached a maximum of 2.9 m. The results of this study can be used to calculate surface displacement values in areas where surface displacement data are not available through ground GNSS base stations.

A Reliability Analysis of Free- Network Adjustment in the Deformation Surveying. (변형측량에서 자유망조정기법의 신뢰성 분석)

  • 유복모;정영동;이석군
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.5 no.2
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    • pp.56-64
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    • 1987
  • The concept of standard error ellipse and confidence ellipse is vtilized in the detection of displaced station which are uncluded in the observational network. In this paper, the influences on the accuracy of unknown stations according to the varied selection and geometrical conditions of fixed stations were evaluated. And then the displaced stations were detected by error ellipse concept, and the amounts of displacement were determined by coordinate differences between epochs which were calculated by fixed point adjustment and free network adjustment. As a result, it is found that the free network adjustment is more efficient in the detection and displacement calculation of displaced stations.

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GPS 관측을 이용한 칠레지진(2010.2.27)에 의한 주변지역 변위발생분석

  • Baek, Jeong-Ho;Jo, Jeong-Ho;Park, Pil-Ho
    • Bulletin of the Korean Space Science Society
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    • 2010.04a
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    • pp.37.2-37.2
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    • 2010
  • GPS 관측자료를 이용하여 최근 발생한 칠레지진에 의한 지각의 변위를 결정하고 결과를 분석하였다. 고정밀 측지용 이중주파수 GPS 수신기 및 안테나가 장착된 관측소의 자료를 처리하면 수mm 정밀도로 관측소의 위치를 결정할 수 있으며, 수년간의 관측자료가 누적되면 연간 mm급의 움직임도 관측할 수 있어 판운동이나 지진, 단층연구 등에 널리 활용되고 있다. 이번 2010년 2월 27일 칠레 중서부에서 발생한 지진은 인근 지역을 30 cm 이상 움직였을 것으로 예상되며 8.8의 대형 지진규모와 많은 인명 및 재산피해를 유발시켜 학계뿐만 아니라 일반 언론에도 많은 주목을 받고 있다. 이 연구에서는 지진이 발생한 지역 부근에 위치한 국제 GPS 기준망의 GPS 관측자료를 처리하여 지진 발생 전후의 변위를 산출하고 분석하였다. 자료처리를 위해 Bernese GPS S/W 5.0을 사용하였고 24시간단위 자료에 대해 이중차분방법과 단독정밀측위방법을 사용하였다. 또한 지진이 발생 도중의 변위를 관찰하기 위해 이동측위방법을 사용하여 30초마다의 움직임을 계산하였다.

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Displacement Analysis of Structures using RTK-GPS/Accelerometer Integration Methods (RTK-GPS와 가속도계 통합계산을 통한 구조물의 변위 해석)

  • Hwang, Jin-Sang;Yun, Hong-Sic;Lee, Dong-Ha;Hong, Sung-Nam;Suh, Yong-Cheol
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.29 no.6
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    • pp.583-591
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    • 2011
  • Accurate observation results of dynamic displacements are essential to the protection of civil structures. In this study, we evaluated the optimal methods of the RTK/GPS Accelerometer integration through comparison and analysis of several experiments results. Two methods will be used to calculate the dynamic displacements from the results of the acceleration data as well as two integration methods for measuring the dynamic, static, and quasi-static displacements by incorporating the displacement results from the RTK-GPS and Accelerometer. By using a Cantilever Beam and LVDT measurement, we were able to ensure that the different displacement comparisons would be reliable and accurate. As a results from experiments, the accelerometer processing method applied by use of accelerometers data was filtering with the double integral using FIR band-pass filter which is most optimal for assessing the dynamic displacements. Also, the integrated method using extracting substitution displacements is suitable for measuring synthetically the dynamic static and quasi-static displacements of civil structures with RTK-GPS and accelerometer.

Effect of Spatial Distribution of Geotechnical Parameters on Tunnel Deformation (지반 물성치의 공간적 분포에 따른 터널 변위 특성 분석)

  • Song, Ki-Il;Cho, Gye-Chun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.8 no.3
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    • pp.249-257
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    • 2006
  • The spatial distribution of design parameters greatly affects tunnel behavior during and after construction, as well as in the long-term temporal responses. However, the tunnel design parameters commonly used in numerical modeling tend to be representative or average values of global-scale properties. Furthermore, the uncertainty and spatial variation of the design parameters increase as the tunnel scale increases. Consequently, the probability of failure also increases. In order to achieve structural stability in large-section tunnels, the design framework must take into consideration the quantitative effect of design parameter variations on tunnel behavior. Therefore, this paper suggests a statistical approach to numerical modeling to explore the effect of spatially distributed design parameters in a circular tunnel. Also, the effect of spatial variation in the lining strength is studied in this paper. The numerical results suggest that the deformation around the tunnel increases with an increase in the variation of the design parameters.

Quantitative Analysis of 3-D Displacements Measurement by Using Holospeckle Interferometry (홀로스펙클 간섭법을 이용한 3차원 변위측정의 정량적 연구)

  • 주진원;권영하;박승옥
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.5
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    • pp.1208-1217
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    • 1993
  • The simple and effective optical technique synthesizing holographic interferometry and speckle photography is presented. The optical system used in this experiment is based on image holography. A cantilever beam located on the precision translator is used to evaluate this measurement system. Experimental results agree well with the actual displacements within the error of 2.8%. As an its application, three dimensional contact deformation in the ball indentation is measured by using this optical system and compared with the numerical analysis by finite element method.