• Title/Summary/Keyword: Settlement stability

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The Practical Simplified Equation for Settlement Evaluation of Counter Facility in Soft Ground Centering on Rubble Mound (연약지반에 설치된 항만 외곽시설의 안전점검을 위한 침하 평가 간편식 제안 - 사석경사제 중심으로)

  • Kim, Yong-Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.6
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    • pp.317-324
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    • 2020
  • In this study, a simplified equation for settlement evaluation suitable for the special conditions of a counter facility is suggested. Recently, counter facilities, especially breakwaters, are constructed on soft ground in distant seas as new-port development projects. A counter facility that resists the external forces by self-weight settles easily when constructed on soft ground. Settlement in a counter facility and breakwater is not an important factor for maintenance than a land facility. On the other hand, the current settlement evaluation criteria are excessive for conducting a safety inspection. A settlement evaluation from a safety inspection followed by "Detailed Guidelines for a safety inspection on a counter facility" is used. A simplified equation was proposed to calculate the maximum settlement by applying the allowable residual settlement or settlement stability evaluation results. The suitability of the simplified equation was assessed compared to the assessed rating from the settlement survey results. The proposed simplified equation showed that the settlement evaluation rating had been upgraded. The proposed simplified equation is expected to be used to evaluate the practical structural stability and functional performance.

Inflence of nearby structures in braced excavation (버팀굴착에서 인접 구조물의 영향평가)

  • 유일형;김형탁
    • Proceedings of the Korean Geotechical Society Conference
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    • 1994.09a
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    • pp.139-148
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    • 1994
  • Rapid industrialization and urbanization caused by the high economic growth of the country requires optimization of land usage as well as the expansion of underground space. Therefore the construction of large and deep basements is inevitable in built up areas where the braced excavation for earth retaining structures may create many problems such as settlement and damages of nearby buildings and underground utilities. In this work, some of major influential factors concerning the stability of braced excavation are investigated and the results are compared with the field observation results. The ground water table, applied strut forces, horezontal wall displacement, infilling materials in the rock joints were found to be the most critical factors influencing the stability of braced walls constructed in the layered ground. Magnituide and type of the wall deformation was closely related to the pattern of the surface settlement. The stability of braced walls are described in terms of strut forces.

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Reinforcement Effect of Marine Structure Foundation by Column Jet Method (CJM 그라우팅에 의한 호안구조물의 기초보강효과)

  • 천병식;양형칠
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.10a
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    • pp.128-131
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    • 2001
  • The purpose of this study is to investigate the application of Column Jet Method(CJM) as countermeasure against settlement and slope sliding of existing marine structure due to embankment load behind reclaimed revetment. CJM is to make high-strengthened body by compacting and grouting cement mortar after forming artificial space in the ground with ground relaxition machine or high pressure water jetting. Before the ground was reinforced by CJM, the result of slope stability analysis was not satisfy the allowable safe ratio, but after the ground was reinforced by CJM, the stability of slope was over the allowable safe ratio and stable, Therefor, the application of CJM to restraint settlement and sliding of marine structure was very satisfactory.

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Measurement of Tunnel Arch Settlements Ahead of and Behind the Tunnel Face Using a Horizontal Inclinometer and Settlement Pins (수평경사계와 천단침하계에 의한 터널막장 전후방의 천단침하 계측)

  • Kim, Cheehwan
    • Tunnel and Underground Space
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    • v.23 no.2
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    • pp.120-129
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    • 2013
  • It is important to measure the displacement behind and ahead of a tunnel face during construction for evaluating mechanical stability by comparing it to a displacement criteria set by tunnel designers. The 30 m long horizontal inclinometer was installed frontward from the tunnel face and the displacement occurred ahead of a tunnel face during excavation was measured by using it. Tunnel arch settlements behind tunnel face were surveyed using a settlement pins on the arch. So total settlement and longitudinal displacement curve were obtained combining settlement measured by both the horizontal inclinometer ahead of tunnel face and the settlement pins behind the tunnel face.

Analysis of Long-Term Settlement Parameter Correlation and Bearing Capacity Reinforcement Effect for Closed Waste Landfill (사용종료 매립장의 장기침하 모델 매개변수 상관성 및 지지력 보강효과 분석)

  • Cho, Young-Kweon;Chae, Young Su
    • Journal of the Korean Geosynthetics Society
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    • v.12 no.4
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    • pp.1-10
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    • 2013
  • Recently, the closed landfills are usually converted into parks or playground by the check the stability of landfill because they settle unevenly making them unsuitable for structures. When the closed landfill reuse, environmental and structural stability is important. To increase the bearing capacity and reduce the probable settlement of a foundation on waste disposal ground, a layer of geosynthetics(Geocell) is placed on the waste disposal ground. In this paper, the analysis of long-term settlement parameter correlation was performed, also the evaluation of bearing capacity reinforcement effect was conducted by field test. The settlement measured in the field, and input the same ground index when an integer to identify each model were compared by calculating the settlement. In addition, by adjusting the parameters of each model to identify the most similar to the value of field measurement parameters were calculated. Based on the analysis results, when the using the Park's model C(intermediate) = 0.0678, the expected settlement is similar to the field measurement results. Also, the bearing capacity of geocell reinforced ground is 1.193~1.554 times higher than that of unreinforced ground.

Finite Element Analysis for the Effects on the Stiffness of the Embankment and Sandmat on the Deformation Property and the Safety of Road Embankment (성토체 및 모래매트의 강성이 하부지반의 변형과 성토체의 안전에 미치는 영향에 대한 유한요소해석)

  • Bae, Woo-Seok;Kim, Jong-Woo;Kwon, Young-Cheul
    • Journal of the Korean Society of Safety
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    • v.22 no.4
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    • pp.57-65
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    • 2007
  • Effects on the stiffness of the embankment and sandmat on the construction safety of road embankment was investigated in this study by the numerical experiments using FEM. Two points was mainly focused in this study especially. First the deformation characteristics by the change of the stiffness of sand mat and embankment was investigated by the analyzing the consolidation settlement at the center of the embankment and the lateral displacement at the toe of the embankment. And, the effect of the stiffness on the stress distribution characteristics was also investigated in this study. Furthermore, slope stability analysis was carried out to gain the safe factor by change the stiffness of the sandmat and the embankment. The objective of the study is supplying the result of the numerical experiments for the geotechnical engineers who use the FEM for the safety design of the soil structures. As a result, the stiffness of the superstructures greatly affects on the deformation characteristics both in consolidation settlement and lateral displacement. However, it can be aware that it is not dominants to the stress distribution in the aspect that the no changes in the residual excess pore water pressure. Therefore, the decision of the stiffness has to be carried out deliberately considering not only the consolidation the magnitude of the settlement and the lateral displacement, but the slope stability.

A Comparative Study on Field Tests for Driven Pile in Static Load Tests (말뚝의 정재하시험을 통한 현장시험 결과 분석)

  • Chun, Byung-Sik;Youn, Hwan-Ho;Youn, Byung-Tae;Kim, Young-Hun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.1117-1124
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    • 2008
  • In This paper, load-settlement curves that obtained from 11 sites were analyzed. At all tests, the load is applied until apparent failure is observed. The validity of the ultimate and yield load estimation method and load calculated from the settlement criterion was investigated through comparison with the measured data. The result indicated that B. Hansen 80% criterion and Stability Plot in ultimate loading decision law almost have been regared as same by comparing measured date and ultimate bearing capacity decided in depending yield loading decision law from 13% to 46% difference have taeyaeen came out when measured data and Davisson was compared, and S-log t from 5% to 41% log P-log S from 14% to 50% difference have been came out. When Settlement standard and measured data was compared difference had been came out about 3% in total settlement 0.1D criterion and from 12% to 35% difference had been came out in net settlement.

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A simple model for ground surface settlement induced by braced excavation subjected to a significant groundwater drawdown

  • Zhang, Runhong;Zhang, Wengang;Goh, A.T.C.;Hou, Zhongjie;Wang, Wei
    • Geomechanics and Engineering
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    • v.16 no.6
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    • pp.635-642
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    • 2018
  • Braced excavation systems are commonly required to ensure stability in construction of basements for shopping malls, underground transportation and other habitation facilities. For excavations in deposits of soft clays or residual soils, stiff retaining wall systems such as diaphragm walls are commonly adopted to restrain the ground movements and wall deflections in order to prevent damage to surrounding buildings and utilities. The ground surface settlement behind the excavation is closely associated with the magnitude of basal heave and the wall deflections and is also greatly influenced by the possible groundwater drawdown caused by potential wall leakage, flow from beneath the wall, flow from perched water and along the wall interface or poor panel connections due to the less satisfactory quality. This paper numerically investigates the influences of excavation geometries, the system stiffness, the soil properties and the groundwater drawdown on ground surface settlement and develops a simplified maximum surface settlement Logarithm Regression model for the maximum ground surface settlement estimation. The settlements estimated by this model compare favorably with a number of published and instrumented records.

Numerical study on stability and deformation of retaining wall according to groundwater drawdown

  • Hyunsung Lim;Jongjeon Park;Jaehong Kim;Junyoung Ko
    • Geomechanics and Engineering
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    • v.33 no.2
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    • pp.195-202
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    • 2023
  • In this study, the ground settlement in backside of retaining wall and the behavior of the retaining wall were analyzed according to the method of groundwater drawdown due to excavation by using two-dimensional(2D) finite element analysis. Numerical analysis was performed by applying 1) fixed groundwater level, 2) constant groundwater drawdown, and 3) transient groundwater drawdown. In addition, the behavior of the retaining wall according to the initial groundwater level, ground conditions, and surcharge pressure in backside of retaining wall was evaluated. Based on the numerical analysis results, it was confirmed that when the groundwater level is at 0.1H from the ground surface (H: Excavation soil height), the wall displacement and ground settlement are not affected by the method of groundwater drawdown, regardless of soil conditions (dense or loose) and surcharge pressure. On the other hand, when the groundwater level is at 0.5H from the ground surface, the method of groundwater drawdown was found to have a significant effect on wall displacement and ground settlement. In this case, the difference in ground settlement presents by up to 4 times depending on the method of groundwater drawdown, and the surcharge load could increase the ground settlement by up to 1.5 times.

Inspeciton for Ground Settlement and Its Contermeasurement Under ${\bigcirc}{\bigcirc}$-Station Passenger Way Adjacent to Ground Excavation (${\bigcirc}{\bigcirc}$역사 지하철 환승통로 주변지반 침하 원인 및 대책에 관한 연구)

  • Yoon, Tae-Gook;Choo, Jin-Ho;Kim, Hong-Kyun;Ko, Hee-Kyu;Han, Dong-Eun
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.2879-2884
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    • 2011
  • Ground settlement has been occurred at asphalt pavement above ${\bigcirc}{\bigcirc}$ station passenger way adjacent to ground excavation with SPS method. In this study, emergency inspection has been conducted 4 detailed areas by KISTEC; SPS, sewage box, 50m box in subway, and ${\bigcirc}{\bigcirc}$ station. Field description and previous reports have been analyzed with the elapsed years. Not only precise inspection with several NDTs but also stability analysis by FLAC have been performed to estimated the tendency of settlement at sunk pavement area. Additional monitoring system and water analysis from sewage and SPS have been examined to scrutinize the reason and maintenance for settlement.

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