• Title/Summary/Keyword: Consolidation Settlement

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Analysis of the Long-term Settlement Behavior Due to the Additional Embankment on the Waste Lime Landfill in Public Waters Reclaimed Land (공유수면 매립지내 폐석회 매립시설의 추가성토에 따른 장기침하 거동 분석)

  • Kang, Jeong Ku;Yi, Yeun Jeung
    • Journal of the Korean Geosynthetics Society
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    • v.21 no.2
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    • pp.1-9
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    • 2022
  • Recently, the reclamation of public waters has been on a downward trend due to environmental problems, but there is a limitation to evaluating environmental characteristics index uniformly. In this study, the stability of settlement behavior on public waters reclaimed land was analyzed using the experimental test. From the primary consolidation influence factors, the characteristics of the waste lime was similar that of clay in process of consolidation. Assuming that the waste lime landfill is the layer reinforced with thin geosynthetic reinforcement, the settlement was predicted by calculating the amount of increase using the Westergaard method. As a result of predicting settlement with degree of consolidation, it was found that the increase in stress was reduced by 40% when the surface layer of the soft ground was reinforce with geotextiles compared to the case where it was not reinforced. In addition, the consolidation behavior characteristics of clay and waste lime were compared using the correlation between the plasticity index and internal friction angle of waste lime. Since the waste lime in the public process of consolidation, it was predicted that long-term settlement will increase further.

A Case Study on the Plan for Settlement Restraint by CGS (CGS 공법에 의한 지반침하억제 사례연구)

  • 천병식;여유현;김우종;황성식;김우철
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.03a
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    • pp.611-618
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    • 2002
  • In this study the CGS as an injection method by low slump mortar was performed the pilot test to confirm the applicability of this method and the effectiveness of settlement restraint. From the results, there has been concluded the construction control standard such as an institutional diameter, space, depth, injection materials, Infection pressure etc. Also, there has been estimated the ground improvement effectiveness which has resulted from the field investigation and consolidation test etc. From the results, in the adjacent ground the CGS, generally, has been confirmed to in-crease ground strength to improve the consolidation characteristic obtained from the field investigation and consolidation test. Especially, the CGS which performed the larger stiffness to the ground has been concluded that the settlement restraint to the ground complicates the ground effect which Increases the bearing capacity and stress assignment. So, the CGS can be considered as an effective method to increase the bearing capacity as well as the settlement restraint of soft ground.

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Reliability Analysis for Optimization of Construction Method of Drain Material (배수재 시공의 최적화를 위한 신뢰성 해석)

  • Ahn, Hyeon-Min;Kim, Moon-Chae;Kim, Daehyeon
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.4
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    • pp.87-96
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    • 2014
  • In this paper, reliability analysis was done on the characteristics of consolidation and settlement for the inner temporary dike where a weak ground improvement construction was applied. When the consolidation analysis on the foundation ground was done, the following conclusions were obtained by conducting the stability analysis on the effect of space of drains, the effect of consolidation time, and the residual settlement and differential settlement. When construction was done with a drain space which satisfied 95% probability of reaching a target consolidation in each divided area, the occurrence of a residual settlement was within the range, which did not exceed 10cm. It was shown that there was almost no possibility of the occurrence of differential settlement, which was above the permissible differential settlement slope.

Comparative Analysis of Final Consolidation Settlement by Degree of Consolidation in Soft Soils of Yeongam-Haenam Areas (영암-해남 연약지반의 압밀도 변화에 따른 최종침하량 비교분석)

  • Kim, Tae-Wan;Nam, Geon;Kim, Jae-Hong
    • Journal of the Korean Geotechnical Society
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    • v.39 no.9
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    • pp.25-33
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    • 2023
  • To effectively improve soft soils, it is necessary to perform ground behavior characteristics and stability management through measurement activities when embankment of structures on soft soils is conducted. However, there are many differences between the actual ground behavior and the initial design plan. To address this issue, this study analyzed the measured settlement in the Yeongam-Haenam areas using the Hyperbolic method to predict the settlement based on the measurement data. From the completion time of the embankment in the target area, the final settlement was predicted through the change in the degree of consolidation by the measurement period. Furthermore, the final settlement according to the change in degree of consolidation was compared and analyzed through finite element analysis and field measurement.

Consolidation Characteristics at the Constant Rate of Strain(CRS) Test (일정변형률(CRS) 시험에서의 압밀특성)

  • Lee, Dal-Won;Kim, Si-Jung
    • Korean Journal of Agricultural Science
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    • v.37 no.3
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    • pp.491-499
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    • 2010
  • This study was carried out to investigate the consolidation characteristics of the remolded clay by the oedometer and the constant rate of strain(CRS) consolidation tests. As the rate of strain increases, the settlement rapidly decreased. As the ratio of the sand in the specimen increases, its effect on the rate of strain to the settlement was reduced. As the effective stress increased, the void ratio decreased, while the rate of strain increased, it did not show a clear variation. The reduction of the void ratio was shown to be less than the oedometer test. The coefficient of vertical consolidation with effective stress showed very large variation around preconsolidation stress, but the rate of strain did not provide significant effects. The rate of strain with effective stress gradually decreased at all tests and mixed ratio of sand. The rate of strain at the constant rate of strain tests showed smaller than in the oedometer test. The coefficient of consolidation at the constant rate of strain tests showed much more increase than in the oedometer test. The ratio of the vertical coefficient of consolidation by the odometer and the constant rate of strain tests showed a large difference according to various tests method and mixing ratio. Therefore, it is recommended that careful attention should be paid to designing the soft ground improvement.

The Influence of Distribution Characteristics of Compression Index on the Spatial Distribution of Consolidation Settlements (압축지수분포 특성이 압밀침하량 분포에 미치는 영향)

  • Kim, Dong-Hee;Kim, Min-Tae;Kim, Kyu-Sun;Lee, Woo-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09b
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    • pp.76-80
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    • 2010
  • This paper describes that estimation methods for the distribution of consolidation settlements to investigate the influence of distribution characteristics of compression index on the spatial distribution of consolidation settlements. When the variation of compression index is considerable, the spatial distribution of compression index is estimated using ordinary cokriging. The spatial distribution of consolidation settlements estimated by considering both the variation of compression index and void ratio (CASE-1) is different from the conventional mean value of all soil properties (CASE-2). The settlement of CASE-1 shows the larger variation at short distances rather than that of CASE-2. Whereas the spatial settlement distribution of CASE-1 is affected by the spatial distribution of compression index and the thickness of consolidation layer, the distribution of CASE-2 is significantly influenced by the distribution of the thickness of consolidation layer.

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Numerical Analysis on Effects of Horizontal Drain Arrangement of Vacuum Consolidation (수평배수재 배열의 진공압밀효과에 대한 수치해석)

  • Park, Byung-Soo;Jeong, Gil-Soo;Lee, Jong-Ho;Yoo, Nam-Jae
    • Journal of Industrial Technology
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    • v.23 no.A
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    • pp.109-118
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    • 2003
  • This paper is results of numerical works of investigating effects of horizontal drain arrangements on vacuum consolidation. Extensive numerical analyses were carried out to find the appropriate arrangements of horizontal drain of vacuum consolidation. Commercially available program of CRISP, well known to be good to modelling the behavior of clay material, was used Cam-clay model, based on the Critical State of Soil Mechanics(CSSM), was used to simulate the geotechnical engineering behavior of clay. Model test results carried out previously in the laboratory were compared with numerically estimated results and it was found that results about consolidational settlement with times were in good agreements. Based on this confirmation, parametric numerical study was performed to investigate effects of horizontal drain arrangements on vacuum consolidation with changing the vertical and horizontal spacings between drains for the given soil properties and vacuum. The effect of distance of drain located in top layer from the surface of the ground on the settlement due to vacuum was also investigated. As a results of numerical analyses, appropriate arrangements of horizontal drain to maximize the consolidation settlement due to vacuum were found. The mechanism of vacuum consolidation about the vacuum pressures being transferred to the effective stresses around drains was also evaluated.

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Determination of Plastic Settlement of Mortar Using Non-contact Laser Measurement Device (레이저 거리측정 실험을 통한 모르타르의 소성침하량 산정)

  • Kwak, Hyo-Gyoung;Ha, Soojun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.4A
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    • pp.549-564
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    • 2008
  • In this paper, the plastic settlement of mortar is analyzed on the basis of the small strain consolidation theory, and the validity of the approach is verified through the comparison with experimental data. First, the amount of settlement caused by self-weight of bulk mortar is measured using a non-contact laser measurement device and the estimation of material parameters related to the settlement of mortar is followed. In advance, another experiment is also performed on mortar with embedded reinforcement to measure the settlement distribution, and the influence of mixture proportions and cover depth on unequal settlement is analyzed. Finally, correlation studies between experimental data and settlement distribution obtained by consolidation analysis represents that the application of consolidation theory to the analysis of plastic settlement of mortar is reasonable.

Estimation of Consolidation Period for Dredged Soil by Mikasa Theory (Mikasa 압밀이론에 의한 준설토지반의 압밀기간 산정에 관한 연구)

  • 주재우;정규향;조진구
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.299-306
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    • 2003
  • Dredged soil experiences large settlement during consolidation because of its high water contents. Large settlement alters the thickness of the consolidation layer greatly with time. However, the consolidation theory proposed by Terzaghi assumes the thickness of the consolidation layer to stay constant. Mikasa has developed a more rational theory considering the change of thickness of consolidation layer but it is not well applied at the site. In this study consolidation tests have been performed using Rowe cell for the four dredged clay samples with a water content of 100%, 120%, 133% and 150%. From the test results compression index characteristics and coefficient of consolidation characteristics have been investigated. Coefficients of consolidation obtained by Terzaghi's and Mikasa's theories, have been evaluated and compared with each other. When Mikasa theory is applied in the field design, the period to reach the required degree of consolidation has been reduced compared with the result by Terzaghi theory because the time factor $T_{v}$ by Mikasa theory decreases with increasing of final strain of consolidation layer, Calculation method consolidation time by Mikasa theory was concisely explained for its practical use.e.

Prediction of Residual Settlement of Ground Improved by Vertical Drains Using the Elasto-Viscous Consolidation Model (I) - Verification of the Applicability of Theory - (탄-점성 압밀이론에 의한 버티칼 드레인 타설지반의 잔류침하 예측 (I) -이론의 적용성 검증)

  • Baek, Won-Jin
    • Journal of the Korean Geotechnical Society
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    • v.23 no.4
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    • pp.69-77
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    • 2007
  • In this study, the consolidation behavior of clayey ground improved by vertical drain method was analyzed by the finite difference method based on the three-dimensional elasto-viscous consolidation theory, which can express the behavior of the secondary consolidation without considering the distinction of the normally consolidated and overconsolidated states. And the applicability of the elasto-viscous consolidation theory was discussed by comparing with the test results obtained from the model test of ground improved by vertical drain system. From these results, it is found that the amount of the settlement when the excess pore water pressure almost dissipated in the clay ground with vertical drains became smaller than that of the one-dimensional condition, and then the amount and rate of the residual settlement at secondary consolidation process became larger than those of the one-dimensional condition. finally, the effect of soil parameter on behavior of consolidation process was investigated by the results of a series of numerical analysis for the normalized and overconsoldiated states.