• Title, Summary, Keyword: 토조

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A Comparative Study on Dynamic Behavior of Soil Containers that Have Different Side Boundary Conditions (측면 경계 조건이 다른 토조들의 동적거동 비교에 관한 연구)

  • Kim, Jin-Man;Ryu, Jeong-Ho;Son, Su-Won;Na, Ho-Young;Son, Jeong-Woong
    • Journal of the Korean Geotechnical Society
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    • v.27 no.12
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    • pp.107-116
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    • 2011
  • Rigid soil containers (or rigid boxes) are often used for 1g shaking table tests. The rigid boxes, however, do not accurately simulate the amplification of ground acceleration and phase difference of seismic motion in the model ground due to the confinement of shear deformation and the reflection of seismic wave at the box walls. Laminar soil containers (or laminar shear boxes) can simulate the free field motion at convincingly superior accuracy than the rigid ones. In this study, the soft ground is modeled for both types of boxes and is subjected to seismic loading using a 1g shaking table. The comparison of the results using the two types of soil containers illustrates that, in case of the rigid box, the ground acceleration shows non uniform distribution and the phase synchronization of input motion. Whereas, the dynamic behavior of the laminar shear box shows good agreement with the free field behaviors such as the amplification of ground acceleration and the occurrence of phase difference.

Soil Deformation Tracking in Model Chamber by Targetless Close-Range Photogrammetry (무타겟 사진측량 기반 모형 토조 내 지반 변위 측정)

  • Lee, Chang No;Oh, Jae Hong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.37 no.6
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    • pp.555-562
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    • 2019
  • This paper presents soil deformation measurement in model chamber based on photogrammetry. We created an aluminum framed acrylic model chamber with soil inside and applied photogrammetry to measure soil deformation caused by loading tests. The soil consists of 40% black and 60% regular sand to create image contrast in soil images. In preprocessing, the self camera calibration was carried out for IOPs (Interior Orientation Parameters), followed by the space resection to estimate EOPs (Exterior Orientation Parameters) using control points located along the aluminum frame. Image matching was applied to measure the soil displacement. We tested different matching window sizes and the effect of image smoothing. Experimental results showed that 65x65 pixels of window size produced better soil deformation map and the image smoothing was useful to suppress the matching outliers. In conclusion, photogrammetry was able to efficiently generated soil deformation map.

Observation of spatio-temporal soil loss in soil erosion experiment using a stereo photogrammetry technique (입체사진측량 기법을 활용한 토조 내 토사유출의 시공간적 변화 관찰)

  • Kim, Youngchan;Shin, Sanghoon;Byun, Jongmin;Paik, Kyungrock
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.306-306
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    • 2015
  • 기존 토사유출실험 연구는 대체로 유출구에서 유사의 총량을 일정한 시간 간격으로 측정했다. 이 같은 방식으로는 총 토사유출량의 시간적 변화는 알 수 있으나, 토사유출의 공간적 분포 변화는 알 수 없기 때문에 토사유출의 취약지점을 파악하고 이를 제시할 수 없다. 본 연구에서는 이러한 한계를 극복하고자 입체사진측량 기법을 도입하여 토사유출의 공간분포를 측정하고 각 지점이 총 토사유출량에 기여하는 정도를 파악하였다. 토조($2m{\times}1m{\times}0.3m$)로부터 약 1.5 m 높이에서 고해상도 디지털 카메라를 이용하여 토조 내 표면을 촬영하였고, 입체사진측량 기법을 이용해 토조 내 수치표고모형(Digital Elevation Models)을 추출하였다. 수치표고모형 추출 과정에서는 고도값의 오차 범위를 확인하였고 격자 해상도를 다양하게 설정하면서 최적의 격자 해상도를 평가해보았다. 최종적으로 구한 일련의 수치표고모형으로부터 토사유출의 시공간적 변화를 파악할 수 있었으며, 이는 토조 내 토사유출 과정에 대한 보다 세밀한 이해를 가져올 것으로 기대된다.

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Study on Pullout Behavior and Determination of Ultimate Uplift Capacity of Pile Driven in Small Pressured Chamber (소형 압력 토조내에 타입된 말뚝의 인발 거동과 극한 인발 지지력 결정에 관한 연구)

  • 최용규
    • Geotechnical Engineering
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    • v.11 no.2
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    • pp.19-28
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    • 1995
  • Based on the various test data acquired in the field, the large pressure chamber and the small pressure chamber, uplift behaviors and method of determining the ultimate uplift capacity of pile driven in small pressure chamber were studied. After uplift pile experienced 2 or 3 sudden slip due to increase of uplift load, complete pullout failure was occurred. Thus, it appears that the ultimate uplift capacity could be identified as the load at displacement where first slip occurs. The ultimate uplift capacity might be determined in every test and the disturbance after first uplift test could be recovered by adding one blow of the drop hammer, which had to depend on the model pile capacity.

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Measurement of Soil Deformation around the Tip of Model Pile by Close-Range Photogrammetry (근접 사진측량에 의한 모형말뚝 선단부 주변의 지반 변형 측정)

  • Lee, Chang No;Oh, Jae Hong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.31 no.2
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    • pp.173-180
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    • 2013
  • In this paper, we studied on measurement of soil deformation around the tip of model pile by close-range photogrammetry. The rigorous bundle adjustment method was utilized to monitor the soil deformation in the laboratory model pile-load test as function of incremental penetration of the pile. Control points were installed on the frame of the laboratory model box case and more than 150 target points were inserted inside the soil around the model pile and on the surface. Four overlapping images including three horizontal and one vertical image were acquired by a non-metric camera for each penetration step. The images were processed to automatically locate the control and target points in the images for the self-calibration and the bundle adjustment. During the bundle adjustment, the refraction index of the acrylic case of the laboratory model was accounted for accurate measurement. The experiment showed the proposed approach enabled the automated photogrammetric monitoring of soil deformation around the tip of model pile.

Behavior of Underground Flexible Pipes Subject to Vehicle Load (차량하중을 받는 지중연성관의 거동특성)

  • 이대수;상현규;김경열
    • Journal of the Korean Geotechnical Society
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    • v.18 no.4
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    • pp.65-73
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    • 2002
  • Underground flexible pipes for electric cables are subject to external loads and surrounding soil pressure. Particularly, strain of flexible pipes is of great concern in terms of safety and maintenance for electric cables. In this paper, stress and strain of flexible pipes with various depth are compared using traditional formula, FEM analysis and model soil box test. The results show that theoretical values are more conservative in strain in comparison with model soil box test and FEM analysis. Considering the strain criteria - maximum 3.5%, flexible pipes can be buried at the depth of 40cm without additional soil improvement. From the result of this study, deformation formula compatible with the field condition was proposed.

A Research for Computation of Bearing Capacity and Settlement of Foundation Considering Scale Effect in Weathered-granite Layer (화강풍화토에서 Scale Effect를 고려한 기초의 지지력 및 침하량 산정에 관한 연구)

  • 박용부;정형식
    • Journal of the Korean Geotechnical Society
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    • v.20 no.1
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    • pp.131-139
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    • 2004
  • When calculating bearing capacity and settlement of actual foundation from plate test result fur design and construction of shallow foundation, scale effect should be considered. But, adequate guide and test result of scale effect were not prepared yet in Korea. So, to analyze the relations of bearing capacity and settlement as the difference of loading plate sizes, model test and field loading test were performed with different loading plate on weathered-granite layer. Model tests were conducted with water content, compaction number, saturated unit weight and plate size(Dl5, 25cm) in soil-box$(2,000\times 2,000\times 1,000mm)$ formed soil layer. Field loading tests were carried out with diameters of loading plate$(D15, 25, 30, 40, 75\times 75, 140\times 210cm)$ on the same soil condition. Finally, we presented the prediction formula of bearing and settlement for computating scale offset in design of shallow foundation through result analysis of load test and numerical simulation on weathered soil and rock.

Performance Evaluation of Hopper Kinetic Trajectory for Riding Type Automatic Transplanter (승용형 채소 정식기의 식부호퍼 운동 궤적 성능평가시험)

  • Kim, Yeon-Soo;Kim, Yong-Joo;Kim, Jeong-Gil;Kim, Tae-Young;Kim, Young-Joo;Lee, Sang-Dae
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • pp.66-66
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    • 2017
  • 국내 농촌의 인구고령화, 여성화 증가로 인한 농촌노동력 감소 문제를 해결하기 위해 농업기계자동화에 관한 연구가 활발히 진행되고 있다. 본 연구는 자동화농업기계 중 자동 이식기의 성능평가 기술을 개발하기 위해 수행되었으며 이를 위해 자동 정식기의 핵심부품인 이식호퍼의 결주율, 이식율, 주간간격, 운동궤적 등을 측정할 수 있는 원형토조 실험장치를 개발하였다. 원형토조 실험장치는 원형토조, 이식호퍼 구동장치, 컨트롤러로 구성되어 있으며 이식호퍼의 회전속도(rpm)를 조절하여 주간간격을 조절할 수 있고 초고속 카메라를 이용하여 이식호퍼의 운동궤적을 측정할 수 있다. 이식작물로 고추, 양배추, 브로콜리의 3종류의 육묘를 이용하여 이식호퍼의 회전속도를 20~60 rpm 구간에서 10 rpm 단위로 속도조건변화를 주고 결주율과 이식율을 측정하였다. 이식호퍼 rpm 속도에 따른 주간거리는 190~560 mm로 나타났다. 각 rpm 단수, 작물별 평균 이식율은 고추육묘가 약 97%, 양배추육묘가 약 94%, 브로콜리육묘가 약 95%로 나타났다. 또한 초고속 카메라를 이용하여 측정한 이식호퍼의 운동궤적을 통해 선진사 제품과 대비하여 차이를 보인 것을 확인하였다. 향후 원형토조 실험장치를 이용해 다양한 작물 및 토양조건에서의 실험 및 토양저항 측정장치 개발을 통해 이식작업 진행중에 호퍼에 걸리는 부하에 대한 성능평가시험을 할 계획이다.

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A Study on The Scale Effect of Landslide Model Tests (산사태 모형실험에서의 Scale Effect에 관한 연구)

  • Jeong, Jisu;Ji, Younghwan;Kim, Yootae;Lee, Seungho
    • Journal of the Korean Geoenvironmental Society
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    • v.12 no.8
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    • pp.5-12
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    • 2011
  • This study was performed to analyze the degree of rainfalls, the duration time of rainfalls, the inclination of slopes and other damage causes depending on the ground condition, when the landslide occurs by the rainfall. Based on that, a big and a small model soil box were compared to examine the features of landslides, which is ultimately for forecasting landslides. An artificial rainfall device was installed in the model box, and the large model box has a real-size slope in it. Also, various measures were fulfilled such as collapse forms, a pore pressure, an earth pressure and moisture contents in order to analyze the effect of the model box size on the landslide mechanism and to test the usability of a small model box as a material for landslide experiments.