• Title/Summary/Keyword: 기초침하

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부산신항 사석층 침하를 고려한 안벽기초의 침하량 분석

  • Gang, Yeon-Ik;Jeong, Jong-Beom;Yang, Sang-Yong
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2007.12a
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    • pp.176-178
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    • 2007
  • 부산신항 북컨테이너터미널 민차부두 1단계 공사에 적용된 안벽기초는 하부 대섬도 연약점토층 개량을 위한 SCP(Sand Compaction Pile) 개량층과 그 상부에 약 6m정도의 사석층으로 구성되어 있다. 안벽은 케이슨식으로 상부의 크레인 풍의 공용하중 작용시에 발생이 예상되는 안벽기초의 과도한 지반침하 방지를 위해 근고블럭에 의한 Preloading 공법이 적용되었다. 따라서, 프리로딩에 의한 하부기초지반의 침하관리가 중요 공사관리 포인트가 된다. 그러나, SCP층이나 사석총에 대한 침하량 예측은 반경험적 방법에 의존하기 때문에 실제와 상당한 차이가 발생하게 된다 본 연구에서는 사석층의 진동다짐에 의한 시공 특성을 반영하기 위해 굴착치환구간의 사석층에 대한 실측값을 이용하여 Terzaghi 변형식의 침하계수 a를 재산정하여 SCP개량구간에 적용함으로써 보다 합리적인 안벽기초의 침하량을 분석하였고 이를 사석층의 여성고 산정에 이용하였다.

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A Study on Settlement according to Height and Ground stiffness on the MSEW on the IPM Bridge (토압분리형 교량의 보강토옹벽의 높이와 기초지반 강성에 따른 침하량 검토)

  • Park, Min-Cheol
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.5
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    • pp.399-409
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    • 2018
  • The mechanically stabilized earth wall (MSEW) of the IPM bridge is an important structure that constitutes the bridge, and supports the horizontal earth pressure and approach slab. Therefore, it is necessary to carefully analyze the settlement of MSEW of the IPM bridge. This study examined the settlement according to the height and ground stiffness on the MSEW on the IPM Bridge. According to the design guideline, the IPM Bridge (2016) was designed to have a height of 4.0 ~ 10.0m and the elastic settlement was calculated. The base area and the grounding pressure of the MSE wall increased linearly with the height, and the elastic settlement also increased linearly. In addition, the stiffness of the foundations satisfying the allowable settlement of the approach slab is a N value of 35 or more. The settlement of finite element analysis was estimated to be smaller than the elastic settlement, and the stiffness of the foundation ground satisfied the allowable settlement of the approach slab above N value of 20. Because the elastic settlement of the MSEW of the IPM Bridge was overestimated, it will be necessary to examine it carefully by finite element analysis.

An Experimental Study on the Relationship between Deformation and Relative Settlement for Weathered-granite (화강풍화토의 변형계수와 상대침하 관계식에 관한 실험적 연구)

  • Park, Yong-Boo
    • Land and Housing Review
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    • v.4 no.1
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    • pp.125-131
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    • 2013
  • To predict the real bearing capacity and settlement of the shallow foundation the plate load test results were used. But there is no field estimation method about igneous weathered soil and rock. Therefore, to predict the settlement equation, the plate load test about igneous weathered soil and rock was done in this study. To analyze the load ~ relative settlement curve by normalization, it did not use normal analysis method, but the load ~ relative settlement (s/B, s : settlement, B : breadth of plate) was used. As a result of normalization by load ~ relative settlement conception, the curve was regular regardless of plate diameter and it was suggested the relationship of in-situ soil condition and results.

Foundation Analysis and Design Using CPT Results : Settlement Estimation of Shallow Foundation (CPT 결과를 이용한 기초해석 및 설계 : 얕은 기초의 침하량 산정)

  • 이준환;박동규
    • Journal of the Korean Geotechnical Society
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    • v.20 no.8
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    • pp.5-14
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    • 2004
  • The settlement of foundations under working load conditions is an important design consideration. Well-designed foundations induce stress-strain states in the soil that are neither in the linear elastic range nor in the range usually associated with perfect plasticity. Thus, in order to accurately predict working settlements, analyses that are more realistic than simple elastic analyses are required. The settlements of footings in sand are often estimated based on the results of in-situ tests, particularly the standard penetration test (SPT) and the cone penetration test (CPT). In this paper, we analyze the load-settlement response of vertically loaded footings placed in sands using both the finite element method with a non-linear stress-strain model and the conventional elastic approach. Based on these analyses, we propose a procedure for the estimation of footing settlement in sands based on CPT results.

Model Tests on the Bearing Capacity and Settlement of Footing Considering Scale Effect (Scale Effect를 고려한 기초의 지지력 및 침하량 산정을 위한 모형실험)

  • 정형식;김도열;김정호
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.343-354
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    • 2003
  • The scale effect should be considered to determine the bearing capacity and settlement of footings from Plate-Load Test, because of the size difference between a footing and a loading plate. To analyze characteristics of bearing capacity and settlement according to the difference of loading plate sizes, model tests were performed with four different sizes of square plate, which are B=10, 15, 20 and 25cm, on five different kinds of subsoil. Based on the analyzed results, this paper also proposes a method of bearing capacity and settlement determination, where scale effect is considered depending on the mixing ratio of sand and clay. Until now, uneconomic constructions have been conducted because of unreasonable evaluation in estimating bearing capacity and settlement of footings from Plate-Load Test in fields. In the application of the formula proposed in this research to field problems, it is expected that evaluation of bearing capacity and settlement of footings can be more reliable and more economic construction can be achieved.

Settlement of Fine Recycled-concrete Aggregates Foundation under Sewage Conduit System (폐콘크리트 재생잔골재의 하수관거 모래기초 적용에 따른 침하 거동)

  • Oh, Je-Ill;Ahn, Nam-Kyu;Lee, Ju-Young
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.5
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    • pp.486-490
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    • 2005
  • Fine recycled-concrete aggregates(RCAs) instead of natural sand were tested for a foundation material under sewage conduit system, which was evaluated based on foundation settlement at various conditions. To obtain this applicability of RCAs, the settlement behavior was simulated with FLAC program based on the difference of material properties, and immediate settlement behaviors and the change of material properties under the simulated drainage conditions also tested at the various loading conditions in the laboratory. Finally, large-scale settlement test in the field was conducted to prove the above feasibilities. Subsequently, the amount of settlement from the FLAC simulation was calculated under $5.0{\times}10^{-6}\;m$ and the extent of settlement and property changes (porosity, permeability and waster absorption) was not noticeable from the laboratory experiments. Also, settlement monitoring from the field experiment showed the consistent results with laboratory experiments except for the consolidation settlement(=5 mm) of the round below the foundation. In summary, adopting fine RCAs as a foundation material for sewage conduit system was resonable based of geotechnical point of view.

Case study on the foundation of a retaining wall for disaster prevention (재난에 대비한 보강토옹벽 기초의 사례연구)

  • Kim, Joon-Seok
    • Proceedings of the Korean Society of Disaster Information Conference
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    • 2017.11a
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    • pp.195-196
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    • 2017
  • 연약한 지반 위에 시공되는 보강토 옹벽이 연약지반의 침하에 대하여 안정성을 분석하고 지반의 처리를 어떻게 하는 것이 향후 재난발생을 예방할 수 있는지에 대하여 침하량을 분석하고 대처 방법에 대하여 분석하였다.

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Reliability and Accuracy Analyses of Prediction Equations for Settlement Calculation of Shallow Foundations Constructed on Sandy Soils (사질토 지반에 시공된 얕은 기초 침하예측식의 신뢰도 및 정확도 분석)

  • Lim, Yu-Jin
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.3
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    • pp.77-86
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    • 2008
  • A database program is constructed by collecting all information related to shallow foundations such as measured load-settlement data, foundation shapes and sizes, properties of soils under the foundation and various measured data obtained from field investigation methods including CPT, PMT and SPT etc.. Based on the database program, a special program module is developed for performing statistical analyses of reliability and accuracy of predicting equations used for calculation of settlement of the shallow foundations. Special interests are focused not only on the settlement, but also on the settlement to width ratio (s/B). Results of the reliability and accuracy analyses on five available settlement equations are provided. Conclusions based on the provided results can be confirmed by extending number of related reliable data about the shallow foundations and can be adapted as guidelines for design of the shallow foundations.

Evaluation of Size Effects of Shallow Foundation Settlement Using Large Scale Plate Load Test (대형 평판재하시험을 이용한 얕은 기초의 침하에 대한 크기효과 평가)

  • Kim, Kyung-Suk;Lee, Sang-Rae;Park, Young-Ho;Kim, Sung-Hwan
    • Journal of the Korean Geotechnical Society
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    • v.28 no.7
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    • pp.67-75
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    • 2012
  • This paper addresses the size effect of shallow foundation settlement in very dense weathered granite soil commonly encountered in bridge foundation. Load-settlement curves measured from the plate load tests of 5 different plate sizes in 2 sites were analyzed. The test results showed that the ground beneath the plate was considered not to reach the failure state and the settlement continuously increased proportionately as load increased. The result implies that settlement would govern the stability or serviceability of foundation on very dense weathered soil. The size effect is expressed as a relationship of subgrade reaction modulus to the size of plate. Compared with the previous relationships, the size effect in this result was more prominent and indicated that settlement prediction using the previous method could possibly underestimate the settlement of foundation in dense weathered granite soil.