• Title, Summary, Keyword: 변위속도

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Relations between Initial Displacement Rate and Final Displacement of Arch Settlement and Convergence of a Shallow Tunnel (저심도 터널의 천단침하 및 내공변위의 초기변위속도와 최종변위의 관계)

  • Kim, Cheehwan
    • Tunnel and Underground Space
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    • v.23 no.2
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    • pp.110-119
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    • 2013
  • It is generalized to measure the arch settlement and convergence during tunnel construction for monitoring its mechanical stability. The initial convergence rate a day is defined from the first convergence measurement and the final convergence defined as the convergence measured lastly. The initial and the final tunnel arch settlement are defined like the preceding convergence. In the study, the relations between the initial and final displacements of a shallow tunnel are analyzed. The measurements were performed in the tunnel of subway 906 construction site in Seoul. The overburden is 10-20 m and the tunnel goes through weathered soil/rock. The width and height of the tunnel are about 11.5 m, 10m, respectively. So this is a shallow tunnel in weak rock. The length of tunnel is about 1,820 m and the tunnel was constructed in 2 stages, dividing upper and lower half. The numbers of measurement locations of arch settlement and convergence are 184 and 258, respectively. As a result, the initial displacement rate and the final displacement are comparatively larger in the section of weathered soil.

The Relationship between Loading Velocity and Ground Heaving Characteristics (재하속도와 지반융기 특성의 상호관계)

  • Oh, Se-Wook
    • Journal of the Korean Geoenvironmental Society
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    • v.7 no.3
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    • pp.77-83
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    • 2006
  • The purpose of this study is to analyze lateral displacement behavior of clay layers in case of the banking in soft ground through model tests. Seven model tests varying with thickness of soft clay and loading velocity are performed to correlate between ground heaving and loading velocity. In case of low loading velocity, vertical settlement below loading plate and small ground heaving are obviously observed. In case of the high loading velocity, it is shown that both soil displacement at the end of a loading plate and surface heaving are large. In addition, the calculated displacements show good agreement with three cases of field measurements in clay with high moisture contents so that we can predict the range of heaving area and the amount of heaving.

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Displacement and Velocity Dependence of Clamped Shape Metallic Dampers (꺽쇠형 강재 댐퍼의 변위 및 속도 의존성)

  • Lee, Hyun Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.2
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    • pp.62-70
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    • 2013
  • The purpose of this study is the displacement and velocity dependence evaluation of clamped shape metallic damper, which were evaluated superior in energy dissipation capacity than straight type slit damper. For this purpose, 6 metallic damper specimens are prepared and dependence test are performed. Test variables are displacement dependence and velocity dependence. According to displacement dependence test results, larger target displacement (50mm) shows lower cyclic numbers and cumulated energy dissipated area than lower target displacement (25mm). Also it shows higher strength and early failure than short target displacement. In velocity dependence evaluation, fast target velocity (60mm/sec) shows lower cyclic numbers and cumulated energy dissipated area than slow target velocity (40mm/sec). Therefore the hysteresis dependence of metallic damper were evaluated as close relation to the loading displacement and velocity conditions.

The Effect of Displacement Rate on Shear Characteristics of Geotextile-involved Ceosynthetic Interfaces (지오텍스타일이 포함된 토목섬유 경계면의 전단특성에 대한 변위속도 효과)

  • 김진만
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.173-180
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    • 2003
  • In spite of its potential importance in the assessment of geosynthetic-related dynamic problems, no serious attempt has yet been made to investigate a probable dependence of dynamic friction resistance of the geosynthetic interface on shear displacement rate. Hence, an experimental study of geosynthetics was carried out on a shaking table, and the relationship between dynamic friction resistance and shear displacement rate of geosynthetic interfaces was investigated. A cyclic, displacement rate-controlled experimental setup was used. The subsequent multiple rate tests showed that interfaces that involve geotextiles have such unique shearing characteristics that shear strengths tend to increase with displacement rate. In contrast, once submerged with water, the shear strength appears to be no longer dependent on the displacement rate, partly due to lubrication effect of water trapped inside the interface. The results of the experimental study can be used in the seismic safety assessment of a landfill cover and slope where the geosynthetic materials are exposed to a relatively low normal stress.

Dynamic Frictional Properties of Geosynthetic Interfaces Involving Only Non-geotextiles (지오텍스타일을 포함하지 않은 토목섬유 경계면의 동적 마찰 특성)

  • Kim Jin-Man
    • Journal of the Korean Geotechnical Society
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    • v.21 no.7
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    • pp.81-89
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    • 2005
  • Relationship between dynamic friction resistances and shear displacement rate, and other frictional characteristics of non-geotextile-involving geosynthetic interfaces was experimentally studied. A cyclic, displacement rate-controlled experimental setup built on a shaking table was used. The subsequent multiple rate tests showed that interfaces that do not involve geotextiles have distinct shearing characteristics that can be differentiated from the interfaces involving geotextiles. Unlike those of the geotextile-involving interfaces, shear behaviors of the interfaces involving only non-geotextiles tend to be not sensitive to shear displacement rate, and are approximately rigid-perfectly plastic.

Estimation of Tunnel Convergence Using Statistical Analysis (통계처리를 활용한 터널 내공변위의 분석에 관한 연구)

  • 김종우
    • Tunnel and Underground Space
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    • v.13 no.2
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    • pp.108-116
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    • 2003
  • Measured convergence data of a tunnel were investigated by means of statistical and regression analysis, where the rock mass were mainly composed of andesite and granite. The rock mass around tunnel were classified by RMR method into five different ratings, and then convergence data which belong to individual ratings were statistically processed to find out the appropriate regression equations. Exponential equations were better coincided with measured data than logarithmic equations. As the number of rock mass rating was increased, the magnitude and standard deviation of convergence were increased. Final convergence data were also investigated to study the relevance with both maximum displacement rate and early measured convergence. Some brief results of their relevance are presented. For instance, the regression coefficient between final convergence and maximum displacement rate was turned out to be 0.87 for this studied tunnel.

Dependency Evaluation According to Damper Strut Type (댐퍼 스트럿 형상에 따른 의존성 평가)

  • Lee, Hyun-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.5
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    • pp.78-86
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    • 2014
  • The purpose of this study is the displacement and velocity dependence evaluation of I type and S type metallic dampers. For this purpose, 12 metallic damper specimens are prepared and dependence test are performed. Test variables are strut type, displacement and velocity dependence. From the evaluation results of dependence tests, number of cycles are fully exceeded than minimum 5 cycles described in ASCE 7-10. According to displacement dependence test results, larger target displacement (50mm) shows lower cyclic numbers and cumulated energy dissipated area than lower target displacement (25mm). Also it show higher strength and early failure than short target displacement. In velocity dependence evaluation, fast target velocity (60mm/sec) shows lower cyclic numbers and cumulated energy dissipated area than target velocity (40mm/sec). As a results of basic properties, dependence evaluation and cumulated energy dissipated area evaluation, dependence capacity of S type metallic damper is far superior than I type.

Three Dimensional Motion of the Center of Mass While Crossing an Obstacle in Young and Older Adults (젊은 성인과 노인의 장애물 보행 시 신체질량중심의 3차원적 움직임)

  • Son, nam-kuk;Kim, hyeong-dong
    • Proceedings of the Korea Contents Association Conference
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    • pp.381-382
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    • 2013
  • 본 연구의 목적은 젊은 성인과 노인의 장애물 보행 시 신체질량중심의 변위와 최대속도를 3차원적으로 비교 분석하여 노인의 낙상위험 및 균형능력을 평가할 수 있는 중요한 요소가 될 수 있는지를 검증하는데 있다. 본 연구의 대상은 건강한 젊은 성인 10명(남성 6명/여성 4명, $24.6{\pm}1.9$세)과 65세 이상 건강한 노인 10명(남성 1명/여성 9명)으로 선정하였다. 각 피험자 신장의 10% 높이의 장애물 보행을 실시하였으며 동작 분석 장비를 통해 신체질량중심의 변위와 최대속도를 3차원적으로 분석하였다. 전후방향에서는 젊은 성인 집단의 변위가 더 크고(p=.019) 최대속도가 더 빠르게 나타났으며(p<.001), 좌우방향에서는 노인 집단의 변위가 더 크고(p=.004), 더 빠르게 나타났다(p<.001). 수직방향에서의 변위는 유의한 차이가 없었고(p=.135), 최대 속도는 젊은 성인 집단이 더 빠르게 나타났다(p<.001). 신체질량중심의 좌우방향에서의 크고 빠른 움직임은 노인의 동적 균형능력 저하로 인해 넘어가는 발(swing limb)의 안정적인 지지면 딛기를 위한 보상적 조절로 여겨지며, 따라서 노인의 낙상위험 및 균형능력을 평가할 수 있는 중요한 요소가 될 수 있을 것으로 사료된다.

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A Short-term Dynamic Displacement Estimation Method for Civil Infrastructures (사회기반 건설구조물의 단기 동적변위 산정기법)

  • Choi, Jaemook;Chung, Junyeon;Koo, Gunhee;Kim, Kiyoung;Sohn, Hoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.3
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    • pp.249-254
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    • 2017
  • The paper presents a new short-term dynamic displacement estimation method based on an acceleration and a geophone sensor. The proposed method combines acceleration and velocity measurements through a real time data fusion algorithm based on Kalman filter. The proposed method can estimate the displacement of a structure without displacement sensors, which is typically difficult to be applied to earthquake or fire sites due to their requirement of a fixed rigid support. The proposed method double-integrates the acceleration measurement recursively, and corrects an accumulated integration error based on the velocity measurement, The performance of the proposed method was verified by a lab-scale test, in which displacement estimated by the proposed method are compared to a reference displacement measured by laser doppler vibrometer (LDV).

A Study for Safety Management on the Basis of Lateral Displacement Rates of Anchored In-situ Walls by Collapse Case Histories (붕괴 사례를 통한 앵커지지 가설흙막이벽체의 수평변위속도에 의한 안전관리 연구)

  • Chung, Dae-Seouk;Lee, Yong-Beom
    • Journal of the Society of Disaster Information
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    • v.14 no.3
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    • pp.367-378
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    • 2018
  • Purpose: The objective of this study is to present a reasonable safety management of the anchored in-situ wall systems constructed in the ground conditions consisting of multi-layered soils underlain by bedrocks in the urban area of Korea. Method: Field measurements collected from collapse case histories with deep excavations were analyzed for the safety management of the wall systems supported by the earth anchors in terms of lateral displacement rates. Results: The average maximum lateral displacement rate in a collapsed zone of the in-situ wall significantly increased upon the completion of the excavation. Particularly, the collapse of the in-situ wall system due to the sliding occurring along the discontinuities of the rock produced a considerably large lateral displacement rate over a relatively short period. Conclusion: For predicting and preventing the collapse of the wall system during or after the excavation work, the utilization of the safety management criteria of the in-situ wall system by the lateral displacement rate was found to be much more reasonable in judging the safety of earthworks than the application of the quantitative management criteria which have been commonly used in the excavation sites.