• Title/Summary/Keyword: Consolidation Settlement

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Evaluation of Spatial Consolidation Settlement by Probabilistic Method (확률론적 방법을 이용한 공간적 압밀침하량 평가)

  • Kim, Dong-Hee;Choi, Young-Min;Ko, Seong-Kwon;Lee, Woo-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.475-479
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    • 2010
  • For a rational evaluation of the spatial distribution of consolidation settlement, it is necessary to adopt probabilistic method. In this study, mean and standard deviation of consolidation settlement of whole analysis region are evaluated by using the spatial distribution of consolidation layer which is estimated from kriging and statistics of soil properties. Using these results and probabilistic method, the area need to be raised the ground level for balancing the final design ground level are determined.

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Influence of Estimation Method of Compression Index on Spatial Distribution of Consolidation Settlement (압축지수의 추정방법이 압밀침하량의 공간적 분포특성에 미치는 영향)

  • Kim, Dong-Hee;Ryu, Dong-Woo;Kim, Min-Tae;Lee, Woo-Jin
    • Journal of the Korean Geotechnical Society
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    • v.26 no.10
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    • pp.39-47
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    • 2010
  • In order to investigate the effect of variation characteristics of compression index on the spatial distribution of consolidation settlement, this study presents the estimation methods of the distribution of consolidation settlement and compares the estimated settlements. When the variation of compression index is considerable, the ordinary cokriging is more reliable in estimating the compression index than ordinary kriging because smoothing effect of ordinary cokriging is smaller than that of ordinary kriging. The spatial distribution of consolidation settlement estimated by considering both the variation of compression index and void ratio (CASE-1) is different from that estimated by using the 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 distributions of compression index as well as the thickness of consolidation layer, that of CASE-2 is significantly influenced by the distribution of consolidation layer thickness.

Field instrumentation and settlement prediction of ground treated with straight-line vacuum preloading

  • Lei, Huayang;Feng, Shuangxi;Wang, Lei;Jin, Yawei
    • Geomechanics and Engineering
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    • v.19 no.5
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    • pp.447-462
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    • 2019
  • The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.

연약지반 장기침하량 예측기법의 적용성 연구

  • 장병욱;우철웅;이경호
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1998.10a
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    • pp.425-430
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    • 1998
  • The theory of consolidation has been achieved remarkable development, but associated properties are very difficult to determine in the laboratory. The theoretical shortcomings of those consolidation theories and uncertainties of associated properties make inevitably some discrepancy between theoretical and field settlements. Field settlement measurement by settlement plate is, therefore, widely used to overcome the discrepancy. Among the various methods of ultimate settlement predictions using field settlement data, hyperbolic method and Asaoka's method are most commonly used because of their simplicity and ability to give a reasonable estimate of consolidation settlement. In this paper, the applicability of hyperbolic method and Asaoka's method has been estimated by the analysis of the laboratory consolidation test and field measured data. It is shown that both hyperbolic method and Asaoka's method are significantly affected by the direction of drainage, and Asaoka's method is better to reflect the properties of the soft foundation than hyperbolic method.

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Consolidation Settlement of Capped Sediment (II): Advective Transport of Pore Water and Analytical Prediction of Settlement (캡이 설치된 퇴적층의 압밀 침하 (II): 간극수의 이동 및 침하의 해석적 예측)

  • Kim, Tae-Hyung;Hong, Won-Pyo;Moo-Young, Horace-K
    • Journal of the Korean Geotechnical Society
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    • v.19 no.3
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    • pp.39-44
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    • 2003
  • Centrifuge test was conducted to simulate the effects of consolidation settlement of capped contaminated marine sediment. A fluorescent dye was used to monitor the movement of pore water through the cap layer. Dye tracer study clearly showed the consolidation induced advective transport of contaminants. Thus, the capping layer must be appropriately designed to reduce the effects of consolidation induced advective transport. The results from the centrifuge test were compared to predictions made by the Primary consolidation, Secondary compression, and Desiccation of Dredged Fill (PSDDF) computer program, which can qualitatively estimate the consolidation settlement of capped marine sediment. Although PSDDF approximated closely the secondary compression in the centrifuge test (i.e., compare data points from 18 to 25 prototype years), the maximum deviation between centrifuge test result and PSDDF prediction was 20 % about prototype time 6 years. Thus, designers should utilize PSDDF consolidation settlement results with caution.

Consolidation Behavior of SCP Improved Ground at Pusan New Port Part 1-1 (부산신항 1-1단계 SCP 개량지반 압밀 특성)

  • JUNG JONG-BUM;YANG SANG-YONG;BYUN JUN-GI
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2004.11a
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    • pp.51-56
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    • 2004
  • The sand compaction pile (SCP) method, which forms a composite ground by driving sand piles into clay deposit, is the most commonly used soil improvement techniques in many countries for more than 30 years. Installation of sand compaction piles reduces the amount of consolidation settlement and increases the bearing capacity of soft clay deposit. In this paper, field survey conducted to investigated the consolidation behavior of the composite ground improved by SCPs. It is suggested that the measured consolidation velocity is later than design theory, however measured consolidation settlement is higher than design theory.

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Load-Settlement Characteristics of Concrete TOP-BASE Foundation on Soft Ground (팽이기초공법(Top-Base Method)의 하중-침하량 분석)

  • Kim, Jae-Young;Jeong, Sang-Seom;Lee, Jae-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.03a
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    • pp.210-221
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    • 2009
  • A new foundation type which is called Top-Base method has been used frequently in engineering practices in Korea. In this study, the settlement behavior of concrete Top-Base foundation on soft ground is investigated since the consolidation settlement of the embedding depth and the effect of footing dimensions are not included in current Korean criterion (2007). To obtain detailed information, the model tests of the Top-Base foundation are performed using the PLAXIS 3D finite element analysis. It is shown that in-situ measurements and finite element analysis of the behavior of foundations indicate that consolidation settlement is reduced up and bearing capacity of the foundation increases up to 50%~100%, compared to the primary non-treated ground. Based on this study, it is found that the Top-Base foundation prevents the lateral deformation of soft ground and reduces its negative dilatancy to the surface settlement, and that the foundation creates rather uniform stress distribution under it to increase its bearing capacity. It is also found that the total settlement of Top-Base foundation was highly dependent on the consolidation settlement and footing configurations.

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Design charts for estimating the consolidation times of reclaimed marine clays in Korea

  • Sang-Hyun Jun;Byung-Soo Park;Hyuk-Jae Kwon;Jong-Ho Lee
    • Geomechanics and Engineering
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    • v.32 no.1
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    • pp.1-20
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    • 2023
  • To predict the consolidation behavior of dredged and reclaimed marine clays exhibiting consolidation settlement with large strains, the finite strain consolidation theory must be used. However, challenges in appropriately applying the theory and determining input parameters make design and analysis studies difficult. To address these challenges, design charts for predicting the consolidation settlement of reclaimed marine clays are developed by a numerical approach based on the finite strain consolidation theory. To prepare the design charts, a sensitivity analysis of parameters is performed, and influencing parameters, such as initial void ratio and initial height, as well as the non-linear constitutive void ratio-effective stresspermeability relation, are confirmed. Six representative Korean marine clays obtained from different locations with different liquid limits are used. The design charts for estimating the consolidation times corresponding to various degrees of consolidation are proposed for each of the six representative clays. The consolidation settlements predicted from the design charts are compared to those in previous studies and at an actual construction site and are found to agree well with them. The proposed design charts can therefore be used to solve problems related to the consolidation of reclaimed marine clays having large strains.

Consolidation Behavior of Soft Ground by Prefabricated Vertical Drains (연직드레인 공법에 의한 연약지반의 압밀거동)

  • 이달원;강예묵
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1998.10a
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    • pp.376-381
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    • 1998
  • The large scaled field test by prefabricated vertical drains was performed to evaluate the superiority of vertical discharge capacity for drain materials through compare and analyze the time-settlement behavior with drain spacing and the compression index and consolidation coefficient obtained by laboratory experiments and field monitoring system 1. The relation of measurement settlement( $S_{m}$) versus design settlement( $S_{t}$) and measurement consolidation ratio( $U_{m}$) versus design consolidation ratio( $U_{t}$) were shown $S_{m}$=(1.0~l.1) $S_{t}$, $U_{m}$=(1.13~l.17) $U_{t}$, at 1.0m drain spacing and $S_{m}$=(0.7~0.8) $S_{t}$, $U_{m}$=(0.92~0.99) $U_{t}$ at 1.5m drain spacing, respectively. 2. The relation of field compression index( $C_{cfield}$) and virgin compression index( $V_{cclab}$) was shown $C_{cfield}$=(1.0~1.2) $V_{cclab}$, But it was nearly same value when considered the error with determination method of virgin compression index and prediction method of total settlement. 3. field consolidation coefficient was larger than laboratory consolidation coefficient, and the consolidation coefficient ratio( $C_{h}$/ $C_{v}$) were $C_{h}$=(2.4 ~ 3.0) $C_{v}$. $C_{h}$=(3.5 ~ 4.3) $C_{v}$ at 1.0m and 1.5m drain spacing and increased with increasing of drain spacingngasing of drain spacingng spacingng

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Analysis of the settlement of Pusan New Port construction site using the settlement prediction methods (침하예측방법들을 이용한 부산신항만 현장 침하 분석)

  • Park, Hyun-Il;Kim, Ha-Young
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.1202-1205
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    • 2009
  • Embankment preloading, in conjunction with prefabricated vertical (PV) drains, was used to accelerate consolidation of marine clays in Pusan New Harbour project. UP to eightteen settlement plates were installed at the ground reclamated site under the embankment fill to monitor the preload performance. This analysis is carried out by five settlement prediction methods including the Asaoka, Hyperbolic, Hoshino, and back-analysis method based on optimization. The field settlement data can be analysed by settlement prediction methods to predict the ultimate settlement and the degree of consolidation of the reclaimed land under charge fill. The authors compared with the analyzed results of the methods.

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