• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.587-596
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• 2009

The fiber bridging model is the crucial factor to predict or analyze the tensile behavior of fiber reinforced cementitious composites. This paper presents the fiber bridging constitutive law considering the distribution of fiber inclined angle and the number of fibers in engineered cementitious composites. The distribution of fiber inclined angle and the number of fibers are measured and analyzed by the image processing technique. The fiber distribution are considerably different from those obtained by assuming two- or three-dimensional random distributions for the fiber inclined angle. The simulation of the uniaxial tension behavior was performed considering the distribution of fiber inclined angle and number of fibers measured by the sectional image analysis. The simulation results exhibit multiple cracking and strain hardening behavior that correspond well with test results.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.213-213
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• 2023

하천의 합류부는 두 하천이 만나 형성되는 지역으로 복잡한 혼합 거동을 보인다. 합류부에서는 실제로 수리 특성이 유황에 따라 다양하게 변화하고 수환경 특성도 함께 변화하며, 이로 인해 본류와 지류에 비해 다양한 생태학적인 종이 분포하는 등 환경적으로 중요구간 중 하나이다. 합류부의 혼합 거동을 이해하기 위해서는 다양한 유황에 따른 수체 혼합 거동을 2차류를 통해 분석하는 것이 중요하다. 해외의 경우 2차류의 패턴을 통해 합류부에서의 혼합 거동을 공간적으로 분석한바 있으나(Riley and Rhoads, 2012), 대부분의 연구들은 중·소규모의 하천을 대상으로 진행되어 대규모 하천에서의 확인은 미흡한 상태이다. 또한, 실제 현장에서 계측을 통한 데이터 획득과 후 처리의 어려움으로 인해 현재 국내에서는 2차류 패턴을 통해 대규모 하천 합류부의 혼합 거동을 확인한 사례는 전무한 실정이다. 따라서, 본 연구에서는 Sontek사의 ADCP를 통해 계측된 수리 데이터를 Rozovskii의 방법을 기반으로 한 2차류로 나타내 낙동강-금호강 합류부에서의 공간적인 수체 혼합을 확인하였다. 혼합거리를 판단하기 위해 합류 이후 혼합의 경계면(Shear Layer)에서 나타나는 2차류의 특이한 패턴(Helical motion)을 주요 지표(Index)로 사용하였다. 그리고, 수질 센서인 YSI EXO2의 수표면 전기전도도의 분포를 통해 합류부에서 본류와 지류의 혼합거리를 산정하였으며, 2차류의 패턴과 비교하였다. 분석 결과, 대규모 하천에서 2차류의 특이한 패턴이 존재함을 명확히 확인하였다. 본류와 지류의 모멘텀 비에 따라 서로 다른 패턴의 혼합양상을 2차류를 통해 확인할 수 있었으며, 2차류의 혼합 패턴과 전기전도도의 분포를 비교 분석하여 합류부에서의 혼합을 3차원적으로 해석하였다.

• Journal of the Korean Geosynthetics Society
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• v.3 no.1
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• pp.3-15
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• 2004

Geogrid reinforced soil structures with segmental block facing have been increased since 1990's, because of the convenience of installation and the flexible appearance. In this paper, the behavior of the segmental reinforced retaining wall was analysed with the results of field monitoring. The height and length of reinforced wall are 12m and 25m, respectively. The field measurement equipments are horizontal and vertical earth pressure cells, settlement plate, strain gauge, inclinometer, and displacement pin. Based on the field monitoring, the horizontal earth pressure was approximately 0.3times higher than that of the theoretical method and the maximum tensile strength of reinforcement was 26.2kN/m. The displacement of facing wall was 23mm at the point of 7.1m height of the wall and toward the wall facing. The results of the study indicate that the segmental reinforced retaining wall is in a stable condition because of good compaction & reinforcement effects, and long period of construction time. Finally, the computer program of SRWall is very useful tool to design the segmental reinforced retaining wall.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.233-243
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• 2008

A tunnel behavior predicted in the investigation and design stage is often different from its actual behavior due to mainly the complexity of ground conditions. In a tunnel construction, therefore, it is necessary to ensure the stability of the tunnel by predicting the behaviors of the ground and the supports through observations and measurements, and modifying immediately excavation and reinforcing methods when necessary. To do so, it is important to be able to predict the final tunnel behavior based on the initial tunnel behavior as early as possible. In this study, the correlations were obtained between the initial and the final convergence by analyzing statistically the convergence measurement data, collected from two domestic road tunnels under construction using NATM. In order to estimate the unknown displacements, occurred during the period between the excavation and the first measurement, two methods were used - one is the method by means of regression analysis using a modified exponential function and the other the method by a simple linear regression analysis using the data measured within the distance from tunnel face equal to the tunnel diameter (D). Finally, the relationships were obtained between the initial and final convergence, including the non-measured displacements estimated from the two different methods, by performing linear regression analyses. The regression analysis results showed that there are clear linear relationships between the initial and final convegence and the difference between the two linear regression equations was not that large for when using the exponential function and the simple linear function to estimate the non-measured displacements.

• Journal of the Korean GEO-environmental Society
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• v.16 no.4
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• pp.5-12
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• 2015

Civil engineers have taken the numerous slope monitoring data for an engineering project subjected to hazard potential of slide. However, the topics on how to deal with and draw out proper information from the data related to the slope behavior have not been widely discussed. Recently, several researchers had installed the real-time monitoring system to cope with slope failure; however they are mainly focused on the hardware system installation. Therefore, this study tries to show how the measured data could be grouped and connected each other. The basic idea of analyzing method studied in this paper came from the clustering, which is the part of data mining analysis. Therefore, at the base of classification of time series data, the authors suggest three mathematical data analyzing methods; Average Index of different displacement ($AD_{i,j}$), Difference of average relative displacement ($\overline{RD}_{i,j}$) and Coordinate system of average and relative displacement ($\overline{RD}$, AD). These analyzing methods are based on the statistical method and failure mechanism of slope. Therefore they showed clustering relationships of the similar parts of the slope which makes the same sliding mechanism.

• Journal of the Korean GEO-environmental Society
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• v.21 no.5
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• pp.5-11
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• 2020

Outliers detection and elimination included in field monitoring datum are essential for effective foundation of unusual movement, long and short range forecast of stability and future behavior to various structures. Integrated outlier analysis system for assessing long term time series data was developed in this study. Outlier analysis could be conducted in two step of primary analysis targeted at single dataset and second multi datasets analysis using synthesis value. Integrated outlier analysis system presents basic information for evaluating stability and predicting movement of structure combined with real-time safety management platform. Field application results showed increased correlation between synthesis value including similar sort of sensor showing constant trend and each single dataset. Various monitoring data in case of showing different trend can be used to analyse outlier through correlation-weighted value.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.545-553
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• 2008

Face mapping and displacement monitoring during tunnel construction are the most influential information for the stability assessment of ground and around structures. Especially, the result of face mapping and displacement analysis is essential to the excavation and support design in NATM which is based on the drilling and blasting. However, there have not been so many studies to put those useful information into practice for decision-making process during construction. The study reviewed the tunnel behaviour based on the RMR rating and displacement monitoring when the geological condition of rock mass varies inevitably. The study analysed the crown settlement using convergence equation in order to compensate the disparity induced by the location and time of measurement and found a distinct relation between the geological condition and the line of influence. As a result of analysing the various parameters related to the tunnel convergence according to the geological condition, the study suggested the basic knowledge about the relation between face mapping and displacement behaviour of tunnel.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.183-185
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• 2012

선박의 다양화와 부두의 제한성으로 인하여 수심이 얕은 수역이나 협소한 부두에 접안 시 소형계류시설 및 부유체를 이용하여 해상 공간을 활용하고 있다. 이를 통하여 다양한 장소에서 접안이 가능하며 나아가 상당한 비용절감 효과를 가질 수 있다. 그러나 소형계류 및 부유체를 활용한 선박의 접안 시 파랑에 의해 부유체와 선박간 충격이 발생할 수 있고 이러한 충격이 대형사고로 발생할 수 있는 위험이 상존함에 따라 계류재 및 부유체의 파랑에 의한 움직임 예측과 분석이 필요하다. 본 연구에서는 계류재 및 부유체 운동해석을 위한 3차원 운동 정보와 가속도를 측정함으 써 거동 특성에 대한 기초 자료를 제공하는 계측시스템을 개발하였고, 이 시스템의 구성 및 원리 등에 대하여 소개하고자 한다.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.111-124
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• 1999

When deep excavation adjacent to an existing structure is performed, it is very important to minimize damage on the structure through the prediction of ground movement. In this paper, finite element analysis was performed to predict the ground movement, based on the data from site investigation and laboratory tests, when deep excavation close to a buried water tank was carried out in soft clay ground. The movement and stabilities of the soil-cement wall(SCW) and the adjacent structure were checked using the results of the analysis and the field measurement. The comparison between the measured and the predicted ground movements showed the significance of the excavation procedure and lowering of water level in the analytical model. In the future, it is needed to improve the prediction method for better estimation of the ground movement.

• Journal of the Korean Geosynthetics Society
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• v.2 no.1
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• pp.15-25
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• 2003

This paper presents the results of instrumentation of a two-level of soil-reinforced segmental retaining wall. Instrumentation items include the lateral wall displacements and the geogrid strains at several locations. The instrumentation is still long carried in order to examine long-term behavior. The result indicate that the upper wall has a significant effect on the behavior of the lower wall doubling the wall moved. The wall also exhibits significant post-construction movements that had ceased several months after the wall completed. The implication of the findings from this study was discussed in great detail.