• Title, Summary, Keyword: 근거리 사진계측기법

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Analysis of ground behavior for model tunnel excavation with pipe roof reinforcement using close range photogrammetric technique (근거리 사진계측기법을 이용한 강관보강 모형터널굴착의 지반거동 분석)

  • Lee, Jung-Hwan;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.4
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    • pp.387-402
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    • 2014
  • In congested urban areas, constructions of tunnel structures have became necessary due to a lack of surface space. The excavation of any tunnel generated the ground disturbances of surrounding ground and displacements is major concern. Therefore, a study of tunnel stability is necessary. In this study, the authors have investigated the stability and failure pattern of tunnel through the model tunnel test. In this study, the close range photogrammetry was used to measure the ground deformation. The measured data was converted to displacement vectors and contours. And then it compared to FE analysis and empirical formula. In addition, this study presented the comparison between steel pipe reinforced model tunnel and unreinforced model tunnel. The ground deformation for both the steel pipe reinforced model tunnel and the unreinforced model tunnel was analysed.

Shearing Characteristics of Aluminium Rods Using Plane Strain - Shear Box Test and Close Range Photogrammetric Technique (평면변형률 전단시험과 근거리 사진계측기법을 통한 알루미늄 봉의 전단특성)

  • Lee, Yong-Joo;Song, Ki-Jung
    • Journal of the Korean Geotechnical Society
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    • v.26 no.8
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    • pp.5-14
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    • 2010
  • To simulate two-dimensional plane-strain conditions in the laboratory model test, the side frictional resistance between the soil and thick glass or plastic sheet of the soil container should be reduced as much as possible. However, in fact this side friction cannot be removed completely. In this paper, the ground model simulated as a multi-sized aluminium rod mixture was introduced to get rid of the side frictional resistance and applied to the laboratory shear box test. In addition, an application of the close range photogrammetric technique to the shear box test was validated. As a result, it was found that a mean value of dilation angle from the close range photogrammetry was close to the dilation angle defined by the curve of shear strain vs. volumetric strain.

Investigation of Pile Behaviour according to Interface Properties - Comparison between Pile Model Test Using Close Range Photogrammetry and Numerical Analysis (경계면 물성치에 따른 말뚝 거동 분석 - 근거리 사진계측을 이용한 모형시험과 수치해석 비교)

  • Lee, Jung-Min;Lee, Yong-Joo
    • Journal of the Korean Geotechnical Society
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    • v.30 no.9
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    • pp.29-39
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    • 2014
  • In this study, model pile-load test with numerical analysis was carried out to compare and analyze pile behaviour according to interface properties. In the model test, Close Range Photogrammetry (CRP) was chosen to measure the ground deformation. In addition, model steel and concrete piles were used. Based on the model pile test, interface elements around the model pile were used to simulate the slip effect. Interface properties were adopted as interface reduction factor $R_{inter}$. Interface reduction factor, $R_{inter}$ plays a key role in the interface properties. Through this study, it was found that the model ground behaviour measured by CRP corresponded well to the one predicted by the numerical analysis. And, the interface strength reduction factor, $R_{inter}$ value of the steel pile was higher than that of the concrete pile.

A study on soil behaviour due to tunnelling under embedded pile using close range photogrammetry (근거리 사진계측을 이용한 매입말뚝 하부 터널 굴착 시 주변 지반의 거동 연구)

  • Kong, Suk-Min;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.4
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    • pp.365-376
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    • 2016
  • Population of urban areas is rapidly increased due to urbanization. This situation leads to lack of surface space. So, underground space has been developed for resolving the problem of congested urban areas. Many studies have researched for this situation. However, previous studies mainly focused on behaviour of structures. Researches about behaviour of soil are lacked. For this reason, this study has investigated interactive behaviour between embedded pile and its surrounding ground due to tunnelling. Soil deformation is observed by the close range photogrammetric method and image processing in the model test. These data are compared with numerical analysis.

Comparison of Shallow Model Tunnel Test Using Image Processing and Numerical Analysis (이미지 프로세싱을 이용한 얕은 터널 모형실험과 수치해석의 비교)

  • Lee, Yong-Joo
    • Journal of the Korean Geotechnical Society
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    • v.22 no.7
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    • pp.5-12
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    • 2006
  • In this study, 2D shallow tunnel model test using close range photogrammetric technique was conducted with aluminium rods simulating continuum granular material. Numerical analysis was also carried out in order to identify the behaviour of subsurface deformations caused by shallow tunnelling. Direction and magnitude of displacement vectors from the model test were identical to the result of numerical analysis based on the model data. In particular, it is shown that the vector direction was toward a point below the tunnel invert level. A narrow "chimney or tulip like" pattern of vertical displacement was confirmed by both the model test and numerical analysis. This behaviour is consistent with the field data. In addition to the qualitative comparison, the quantitative result of subsurface settlements according to 2D volume loss showed good agreement between the model test and numerical analysis. Therefore, close range photogrammetric technique applied in the model test may be used to validate the result from the continuum numerical analysis.

Measurement of ground behaviour due to tunnelling using No-target program in laboratory model test (실내모형시험에서 No-target 프로그램을 이용한 터널 굴착으로 인한 지반거동 측정)

  • Lee, Jong-Hyun;Lee, Chang-No;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.3
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    • pp.397-418
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    • 2019
  • It is very important to understand and analyze the interactive behaviour between ground and adjacent structures due to tunneling. With many technological advancement in modern society, numerous methods for analyzing the interactive behaviour are used in a wide range of civil engineering fields. Close range photogrammetry is mainly being used in the field of geotechnical engineering and research on measuring methods associated with GeoPIV has been currently increased. Originally, the close range photogrammetry using target points and aluminum rods for VMS (Vision Measurement System) program has been used. However, applying this has a problem that external errors can be occurred because the target points are artificially installed by hand, and if the grid between points is being wider or narrower, deficient data can be obtained. Therefore, in this study, MATLAB-based No-target program that can analyze displacement without using target was developed. Additionally, this study focused on comparison and verification with existing program through numerical analysis and laboratory model test. Three cases of Greenfield condition, Strip foundation, and Pile foundation were analyzed. From results of VMS program and No-target program, the error rate and reliability of the total displacement and the vertical displacement were analyzed. It was also compared and verified through the finite element numerical program, PLAXIS.

Investigation of soil behaviour due to excavation below the grouped pile according to shape of tunnel station (터널 정거장 형상에 따른 군말뚝 하부 굴착 시 지반거동 연구)

  • Kong, Suk-Min;Oh, Dong-Wook;Lee, Jong-Hyen;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.20 no.1
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    • pp.83-97
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    • 2018
  • Tunnels are widely used for special purposes including roads, railways and culvert for power transmission, etc. Its cross-section shape is determined by uses, ground condition, environmental or economic factor. Many papers with respect to behaviours of adjacent ground and existing structure tunnelling-induced have been published by many researchers, but tunnel cross-section have rarely been considered. A collapse of tunnel causes vaster human and property damage than structures on the ground. Thus, it is very important to understand and analyse the relationship between behavoiurs of ground and cross-section type of tunnel. In this study, the behaviour of ground due to tunnel excavation for underground station below the grouped pile supported existing structure was analysed through laboratory model test using a trap-door device. Not only two cross-section types, 2-arch and box, as station for tunnel, but also, offset between tunnel and grouped pile centre (0.1B, 0.25B, 0.4B) are considered as variable of this study. In order to measure underground deformation tunnelling-induced, Close Range Photogrammetry technique was applied with laboratory model test, and results are compared to numerical analysis.

Analysis of pile load distribution and ground behaviour depending on vertical offset between pile tip and tunnel crown in sand through laboratory model test (실내모형시험을 통한 사질토 지반에서 군말뚝과 터널의 수직 이격거리에 따른 하중분포 및 지반거동 분석)

  • Oh, Dong-Wook;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.3
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    • pp.355-373
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    • 2017
  • Tunnelling in urban areas, it is essential to understand existing structure-tunnel interactive behavior. Serviced structures in the city are supported by pile foundation, since they are certainly effected due to tunnelling. In this research, thus, pile load distribution and ground behavior due to tunnelling below grouped pile were investigated using laboratory model test. Grouped pile foundations were considered as 2, 3 row pile and offsets (between pile tip and tunnel crown: 0.5D, 1.0D and 1.5D for generalization to tunnel diameter, D means tunnel diameter). Soil in the tank for laboratory model test was formed by loose sand (relative density: Dr = 30%) and strain gauges were attached to the pile inner shaft to estimate distribution of axial force. Also, settlements of grouped pile and adjacent ground surface depending on the offsets were measured by LVDT and dial gauge, respectively. Tunnelling-induced deformation of underground was measured by close range photogrammetric technique. Numerical analysis was conducted to analyze and compare with results from laboratory model test and close range photogrammetry. For expression of tunnel excavation, the concept of volume loss was applied in this study, it was 1.5%. As a result from this study, far offset, the smaller reduction of pile axial load and was appeared trend of settlement was similar among them. Particulary, ratio of pile load and settlement reduction were larger when the offset is from 0.5D to 1.0D than from 1.0D to 1.5D.

A Study on the Pile Behaviour Adjacent to Tunnel Using Photo Imaging Process and Numerical Analysis (Photo Imaging Process 기법 및 수치해석을 이용한 터널주변 파일기초거동에 대한 연구)

  • Lee Yong-Joo
    • Journal of the Korean Geotechnical Society
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    • v.21 no.9
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    • pp.87-102
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    • 2005
  • In the congested urban areas, tunnelling close to existing structures or services often occurs due to the lack of surface space so that tunnelling-induced ground movements may cause a serious damage to the adjacent structures. This study focused on the two dimensional laboratory model pile-soil-tunnelling interaction tests using a close range photogrammetric technique. Testing equipments and procedures were Introduced, particularly features of aluminium rods regarded as the frictional granular material. The experimental result showed that the photo imaging process by the VMS and EngVis programs proved to be a useful tool in measuring the pile tip movements during the tunnelling. Consequently, the normalised pile tip movement data for the influence zones can be generated by the laboratory model tests using the Photogrammetric technique. This study presents influence zones associated with the normalized pile tip settlements due to tunnelling in the cohesionless material. The influence zones were Identified by both a laboratory model test and a numerical analysis. The normalized pile tip movements from the model test were in good agreement with the numerical analysis result. The influence zones proposed in this study could be used to decide the reasonable location of tunnel construction in the planning stage. However, the scale of model pile and model tunnel sizes must be carefully adjusted as real ones for practical application considering the ground conditions at a given site.

Pile Load Transition and Ground Behaviour due to Development of Tunnel Volume Loss under Grouped pile in Sand (사질토 지반에서 터널체적손실 증가에 따른 군말뚝의 하중변이와 지반거동)

  • Oh, Dong Wook;Lee, Yong Joo
    • Journal of The Korean Society of Civil Engineers
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    • v.37 no.2
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    • pp.485-495
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    • 2017
  • A development of underground space is very useful solution to slove problem occurred from ground surface enlargement in urban areas due to the growth of population, tunnelling is the most popular way and widely used. Researches regarding tunneling-induced pile-soil interactive behaviour have been conducted by many researchers. A study on pile axial force distribution due to tunnelling through laboratory model test, however, is being rarely carried out. In this study, therefore, authors investigate ground behaviour due to tunnelling below grouped pile subjected vertical load as well as pile axial force distribution. A concept of volume loss is used to express tunnel excavation, which is normally applied to 1~2% for tunnelling in soft ground. In this study, however, 10% of that applied to investigate failure mechanism. As a result of laboratory model test, a decrease of pile axial force occurs at 1.5% of volume loss, settlement of grouped pile is 1.2~4.7 times greater than the adjacent ground surface one. Ground deformations at 1.5% of volume loss are measured using Close Range Photogrammetry and compared with results from numerical analysis.