Characterization of Complete Radial Displacement of Tunnel Using a Horizontal Inclinometer

Chung, So-Keul,Ryu, Dong-Woo,Jang, Won-Il,Yang, Hyung-Sik 한국암반공학회 2010 Geosystem engineering Vol.13 No.2

Measuring the displacement of a tunnel is prerequisite in evaluating the stability, which also makes it possible to understand the geological condition ahead of the tunnel face. In fact, the displacement of a tunnel occurs before, during and after the excavation. Generally, the measurement is undertaken only behind the face, which allows a certain amount of displacement, the so-called 're-measurement-displacement' The measured displacement is only a part of the total radial displacement. Therefore, the pre-measurement-displacement should be determined in order to characterize the complete radial displacement of the tunnel. A horizontal inclinometer was used to measure the degree of settlement ahead of the tunnel face at the study site, which was relatively easy to install from the other portal of the tunnel. The results from the measurement of the settlement ahead of the face enabled a complete radial displacement curve to be constructed using a nonlinear regression analysis. It was found that the crown displacement of the tunnel at the study site started to occur at a distance equivalent to three times of the tunnel diameter ahead of the tunnel face. Taking into consideration the complete displacement characteristics, the possible settlement could be about 40% of the total displacement of the tunnel. Based on the complete radial displacement, it was possible to determine the appropriate support characteristics and the time of installation.

Characterization of Complete Radial Displacement of Tunnel Using a Horizontal Inclinometer

류동우,정소걸,장원일,양형식 한국자원공학회 2010 Geosystem engineering Vol.13 No.2

Measuring the displacement of a tunnel is prerequisite in evaluating the stability, which also makes it possible to understand the geological condition ahead of the tunnel face. In fact, the displacement of a tunnel occurs before, during and after the excavation. Generally, the measurement is undertaken only behind the face, which allows a certain amount of displacement, the so-called ‘pre-measurement-displacement’. The measured displacement is only a part of the total radial displacement. Therefore, the pre-measurement-displacement should be determined in order to characterize the complete radial displacement of the tunnel. A horizontal inclinometer was used to measure the degree of settlement ahead of the tunnel face at the study site, which was relatively easy to install from the other portal of the tunnel. The results from the measurement of the settlement ahead of the face enabled a complete radial displacement curve to be constructed using a nonlinear regression analysis. It was found that the crown displacement of the tunnel at the study site started to occur at a distance equivalent to three times of the tunnel diameter ahead of the tunnel face. Taking into consideration the complete displacement characteristics, the possible settlement could be about 40% of the total displacement of the tunnel. Based on the complete radial displacement, it was possible to determine the appropriate support characteristics and the time of installation.

Computer vision-based remote displacement monitoring system for in-situ bridge bearings robust to large displacement induced by temperature change

Soojin Cho,Byunghyun Kim,Junhwa Lee,Sung-Han Sim,Byung Ho Park 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.5

Efficient management of deteriorating civil infrastructure is one of the most important research topics in many developed countries. In particular, the remote displacement measurement of bridges using linear variable differential transformers, global positioning systems, laser Doppler vibrometers, and computer vision technologies has been attempted extensively. This paper proposes a remote displacement measurement system using closed-circuit televisions (CCTVs) and a computer-vision-based method for in-situ bridge bearings having relatively large displacement due to temperature change in long term. The hardware of the system is composed of a reference target for displacement measurement, a CCTV to capture target images, a gateway to transmit images via a mobile network, and a central server to store and process transmitted images. The usage of CCTV capable of night vision capture and wireless data communication enable long-term 24-hour monitoring on wide range of bridge area. The computer vision algorithm to estimate displacement from the images involves image preprocessing for enhancing the circular features of the target, circular Hough transformation for detecting circles on the target in the whole field-of-view (FOV), and homography transformation for converting the movement of the target in the images into an actual expansion displacement. The simple target design and robust circle detection algorithm help to measure displacement using target images where the targets are far apart from each other. The proposed system is installed at the Tancheon Overpass located in Seoul, and field experiments are performed to evaluate the accuracy of circle detection and displacement measurements. The circle detection accuracy is evaluated using 28,542 images captured from 71 CCTVs installed at the testbed, and only 48 images (0.168%) fail to detect the circles on the target because of subpar imaging conditions. The accuracy of displacement measurement is evaluated using images captured for 17 days from three CCTVs; the average and root-meansquare errors are 0.10 and 0.131 mm, respectively, compared with a similar displacement measurement. The long-term operation of the system, as evaluated using 8-month data, shows high accuracy and stability of the proposed system.

정밀 화상계측법을 이용한 암반변위 계측시스템

황재윤(Jae-Yun Hwang) 한국암반공학회 2011 터널과지하공간 Vol.21 No.6

지하공간, 터널, 사면 등 암반구조물의 안정성 평가하기 위해서 필요한 것은 암반변위의 계측이다. 암반구조물의 계측은 아직도 줄자, 레벨 또는 토탈스테이션 등을 이용하는 계측 방법에 의존하고 있는 것이 일반적인 실정이다. 하지만 이러한 방법들은 많은 결점들을 가지고 있어 새로운 방법의 모색이 필요하다. 본 연구에서는 암반구조물에서의 정보화 설계시공의 계측기법으로 개발한 정밀 화상계측법을 이용한 암반변위 계측시스템을 제안하고, 건설 중에 있는 터널에 적용했다. 실제 건설 중에 있는 터널현장에 적용하여 계측결과를 비교 검토함으로써, 개발한 정밀 화상계측법을 이용한 암반변위 계측시스템의 유효성과 적용성에 대한 검증을 하였다. For the purpose of evaluating the safety of rock structures such as underground caverns, tunnels and slopes, rock displacement measurement is carried out to identify the behavior of rock masses. Tapes, levels, and total stations are usually applied to the displacement measurement. These tools, however, are weighed down by many disadvantages. In this study, a new displacement measurement system by precise vision metrology was proposed for the observational design and construction method of rock structures, and then applied to a tunnel under construction. Comparisons and investigations of the measurement of the tunnel have confirmed the effectiveness and applicability of the developed measurement system.

디지털 영상 계측 기술의 영향인자에 따른 정밀도 분석

김광염,김창용,이승도,이정인 한국지반공학회 2007 한국지반공학회논문집 Vol.23 No.12

This study has reviewed the applicability of displacement measurement by using a digital vision technique based on typical photogrammetric methods. In this study, a series of experimental measurements have been performed in order to improve the accuracy of digital vision measurement by establishing criteria of factors of various vision measurements. It is found that the digital vision measurement tends to show higher accuracy as the image size (resolution) and the focal length become larger and the distance to an object becomes closer. It is also observed that measurement error decreases with processing as many images as possible in various angles. Applicability on high-resolution displacement measurement is proved by applying the digital vision measurement developed in this study to a large scale loading test of concrete lining.

사면의 지표변위 측정을 위한 레이저 거리측정기의 활용

조용찬(Yong-Chan Cho),송영석(Young-Suk Song) 한국지반신소재학회 2014 한국지반신소재학회 논문집 Vol.13 No.1

본 연구에서는 레이저 거리측정기를 이용하여 사면의 지표변위를 효과적으로 측정하는 방법을 제안하였다. 기존 사면의 지표변위 혹은 지중변위를 측정하기 위한 복잡하고 고가의 장비 대신에 제안된 방법을 적용할 경우 보다 간편하고 쉽게 지표변위를 측정할 수 있다. 레이저 거리측정기는 적색 레이저를 측정을 원하는 피사체에 시준하면 반사되는 레이저를 이용해 거리를 측정하는 기기로 작동방법이 용이하고 측정정밀도도 아주 높으며, 가격이 저렴한 장점이 있다. 제안된 방법의 활용가능성을 검토하기 위하여 실제 지표변위가 지속적으로 발생되는 현장에 적용하였다. 대상지역은 석탄폐석 적치장의 영향으로 하부에 위치하는 절취사면 및 자연사면의 여러 위치에서 지표변위가 발생된 현장이다. 대상지역에 지표변위를 직접적으로 측정하기 위하여 6개의 측정구간과 26개의 측정지점을 선정하였다. 일정한 기간 동안 제안된 방법을 이용하여 측정한 결과 누적 지표변 위량 뿐만 아니라 지표변위속도까지 측정이 가능하였다. 그리고 이들 결과를 종합적으로 분석하여 지표변위 발생방향을 확인 및 예측할 수 있다. In this study, the method to measure effectively the ground surface displacement of slope was proposed using the Laser Distance Measurer (LDM). Applying the proposed technique is more simple and easier than the complicated and high-priced instrument to measure the ground surface displacement. LDM is an instrument that the red laser aimed at the target and then the reflected laser used for calculating the distance. The advantages of LDM are easy operating method, high measurement precision and lower in price. To check the feasibility, the proposed method applied to the real site that the ground surface displacement of slope was occurred continuously. The ground surface displacements were occurred in various points of the natural and cut slopes located at the lower part of coal mine waste heap due to the load of waste heap. To measure directly the ground surface displacement in this site, 6 measurement sections and 26 measurement points were selected. As the result of the displacement measured by the proposed technique within a certain period time, the accumulative ground surface displacement could be measured as well as the velocity of displacement could be estimated. Also, the progress direction of ground surface displacement can be confirmed and predicted through the analysis of all measured result.

Image-based structural dynamic displacement measurement using different multi-object tracking algorithms

X.W. Ye,C.Z. Dong,T. Liu 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.17 No.6

With the help of advanced image acquisition and processing technology, the vision-based measurement methods have been broadly applied to implement the structural monitoring and condition identification of civil engineering structures. Many noncontact approaches enabled by different digital image processing algorithms are developed to overcome the problems in conventional structural dynamic displacement measurement. This paper presents three kinds of image processing algorithms for structural dynamic displacement measurement, i.e., the grayscale pattern matching (GPM) algorithm, the color pattern matching (CPM) algorithm, and the mean shift tracking (MST) algorithm. A vision-based system programmed with the three image processing algorithms is developed for multi-point structural dynamic displacement measurement. The dynamic displacement time histories of multiple vision points are simultaneously measured by the vision-based system and the magnetostrictive displacement sensor (MDS) during the laboratory shaking table tests of a three-story steel frame model. The comparative analysis results indicate that the developed vision-based system exhibits excellent performance in structural dynamic displacement measurement by use of the three different image processing algorithms. The field application experiments are also carried out on an arch bridge for the measurement of displacement influence lines during the loading tests to validate the effectiveness of the vision-based system.

Measurement of Intra-Fraction Displacement of the Mediastinal Metastatic Lymph Nodes Using Four-Dimensional CT in Non-Small Cell Lung Cancer

Suzhen Wang,Jianbin Li,Yingjie Zhang,Wei Wang,Fengxiang Li,Tingyong Fan,Min Xu,Qian Shao 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.4

Objective: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). Materials and Methods: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. Results: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). Conclusion: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy. Objective: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). Materials and Methods: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. Results: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). Conclusion: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy.

토사비탈면 붕괴에 대한 계측관리기준 제안: 지표 경사를 중심으로

최선규,정민수,석재욱,정향선,송효성 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.7

This research studied slope behavior and the development of measurement management criteria(MMC) for soil slope failure based on surface inclination by conducting a slope failure experiment with surface inclination measurement. In particular, a real scale steep-slope failure simulator was used in the slope failure experiment, and the displacement behaviors were measured and analyzed using a digital camera, displacement measurement, and inclination measurement to develop the MMC. Specifically, the displacement and inclination behaviors followed a polynomial model because two methods could measure the surface behavior of a slope. In addition, the graded MMC determined the 'surface inclination velocity' with the same method used for the MMC from surface displacement. Additionally, four types of MMC were determined for 'Watch-Starting point when value is detected', 'Caution-Starting point of constant velocity', 'Warning-End point of constant velocity', and 'Alert-End point of acceleration'. Based on the results of the research, four graded MMC results were obtained for 'Watch-Starting point when value is detected', 'Caution-0.04°/min', 'Warning-0.22°/min', and 'Alert-1.74°/min'. Also, each determined MMC exhibited reliability from the other slope failure experiment with different soils and a comparison with the corresponding MMC from surface displacement. 본 논문은 지표 경사계를 설치한 비탈면 붕괴실험을 통해 지표 경사 기반의 비탈면 거동 분석 및 지표 경사 기반의 계측관리기준 개발연구를 수행하였다. 지표 경사 기반 계측관리기준 개발을 위해 실규모 급경사지 붕괴 시뮬레이터를 활용하여 비탈면 붕괴를 유도하였으며, 붕괴과정 동안의 지표 거동을 영상촬영, 지표 변위계 그리고 지표 경사계를 이용하여 측정 및 분석하였다. 분석 결과 지표 변위 거동과 지표 경사 거동 모두 다항형의 거동을 보이는 것으로 확인되었으며, 이는 두 계측기 모두 직접적인 지표의 변화를 측정하는 방법이기 때문으로 판단된다. 따라서, 지표 경사의 계측관리기준은 다항형 모델을 기반으로 설정하였으며, 계측관리기준의 단위는 ‘지표 경사속도’로 설정하였다. 단계별 관리기준은 ‘관심단계-계측시점’, ‘주의단계-등속의 시점’, ‘경계단계-등속의 종점’, ‘심각단계-과속의 종점’인 4단계로 설정하였다. 데이터 분석을 통한 최종 산정한 계측기준은 ‘관심단계-계측시점’, ‘주의단계-0.04°/min’, ‘경계단계-0.22°/min’, ‘심각단계-1.74°/min’로 제안하였다. 본 연구에서 제안한 단계별 계측관리기준은 추가적인 실증실험을 통한 데이터 분석 및 지표 변위 기반의 계측관리기준과의 계측 경보 발령 비교를 통해 신뢰성을 검증하였다.

A vision-based system for dynamic displacement measurement of long-span bridges: algorithm and verification

X.W. Ye,Y. Q. Ni,T.T. Wai,K.Y. Wong,X.M. Zhang,F. Xu 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.12 No.4

Dynamic displacement of structures is an important index for in-service structural condition and behavior assessment, but accurate measurement of structural displacement for large-scale civil structures such as long-span bridges still remains as a challenging task. In this paper, a vision-based dynamic displacement measurement system with the use of digital image processing technology is developed, which is featured by its distinctive characteristics in non-contact, long-distance, and high-precision structural displacement measurement. The hardware of this system is mainly composed of a high-resolution industrial CCD (charge-coupled-device) digital camera and an extended-range zoom lens. Through continuously tracing and identifying a target on the structure, the structural displacement is derived through cross-correlation analysis between the predefined pattern and the captured digital images with the aid of a pattern matching algorithm. To validate the developed system, MTS tests of sinusoidal motions under different vibration frequencies and amplitudes and shaking table tests with different excitations (the El-Centro earthquake wave and a sinusoidal motion) are carried out. Additionally, in-situ verification experiments are performed to measure the mid-span vertical displacement of the suspension Tsing Ma Bridge in the operational condition and the cable-stayed Stonecutters Bridge during loading tests. The obtained results show that the developed system exhibits an excellent capability in real-time measurement of structural displacement and can serve as a good complement to the traditional sensors.