• Title/Summary/Keyword: Secondary consolidation settlements

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A Consolidation Settlement Prediction Considering Primary and Secondary Consolidation (1차와 2차 침하를 고려한 압밀침하량 예측)

  • Lee, Dal-Won;Jeong, Seong-Gyu
    • Journal of The Korean Society of Agricultural Engineers
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    • v.47 no.1
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    • pp.61-68
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    • 2005
  • In this study, it was proposed that an equation for predicting consolidation settlement on soft clay ground, which separate total settlement into primary and secondary consolidation settlement equation. The consolidation settlements by the proposed equation and by the measured settlements from laboratory model test were compared and verified for its application. It was appeared that the proposed equation from the laboratory model test approach to be more realistic comparing to !the result of Terzaghi's equation. From the above application, it was concluded that the final settlement prediction by. the Hyperbolic, Asaoka methods is needed to the initial settlement but the proposed equation could be much applicable in the lacking condition of measured data of the initial period.

$C_a/C_c$ for Soft Clay at the Southern Port of Korea by Laboratory Consolidation Tests (실내압밀시험에 의한 남해안지역 연약점토의 $C_a/C_c$ 평가)

  • 김규선;임형덕;이우진
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.02a
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    • pp.70-77
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    • 1999
  • Consolidation settlements on soft clay are often large and potentially damaging to structures. Currently, large-scale projects are in progress in Korea. These structures will be constructed on both thick and soft clay layers, and so the accurate evaluation of magnitude of settlement is required at every step in design and construction. Especially, secondary compression play an important role in consolidation settlements on soft clay. Generally, the magnitudes of secondary compression are evaluated by laboratory and in-situ consolidation tests or by empirical $C_{a/}$ $C_{c}$ relationships. The empirical $C_{a/}$ $C_{c}$ may not be only economical, but a fast and powerful tool in estimating secondary consolidation settlement. However, databases of the $C_{a/}$ $C_{c}$ relationship for sites in Korea are currently insufficient. The purpose of this study is to investigate the relationship of $C_{a/}$ $C_{c}$, on marine clay near the southern sea in Korea. In this study a series of incremental loading consolidation tests (measuring base pore water pressure) are performed. It was found that the $C_{a/}$ $C_{c}$ on undisturbed marine clay equaled 0.0397. This value is similar to the value proposed by Mesri and Castro(1987) for inorganic clay and silt. and silt. and silt.

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A Prediction of Long-Term Settlement in Large Reclamated Sites Using Laboratory Consolidation Tests and GIS Techniques (실내압밀시험과 GIS 기법을 이용한 대규모 매립지역의 장기침하량 예측)

  • Park, Sa-Won;Kim, Hong-Taek;Park, Sung-Won;Baek, Seung-Cheol;Park, Sang-Kwon
    • Journal of the Korean GEO-environmental Society
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    • v.7 no.3
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    • pp.5-19
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    • 2006
  • The secondary consolidation settlement of soft clay is generally very little compared to the total settlement and occurs very slowly during long-term period. However the secondary consolidation settlement is comparatively large amount in organic and heavily compressed clay and is a very important engineering factor. In order to reduce residual settlements in reclaimed soft ground, the preloading method is often used. In this study, in order to determine reasonable long-term settlements of large reclaimed site, laboratory incremental loading consolidation tests and surcharging consolidation tests are performed. Sampling was done at Incheon area of west coast and Gwangyang area of south coast in Korea. The characteristics of secondary consolidation have obtained through laboratory tests and analyzed systematically to predict long-term settlements. Additionally, the location data and laboratory test results are correlated by using GIS(geographic information system). The secondary consolidation settlement of the site was predicted based on D/B and the operation technique and estimation technique of space of GIS.

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$C_a/C_c$ for Marine Clay at Southern Part of Korea by Laboratory Consolidation Tests (실내압밀시험에 의한 남해안 해성점토의 $C_a/C_c$)

  • 김규선;임형덕;이우진
    • Journal of the Korean Geotechnical Society
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    • v.15 no.6
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    • pp.87-98
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    • 1999
  • Consolidation settlements on soft clay are often greatly and potentially damaging to structures. Currently, large-scale projects are in planning or progressing in Korea. These structures will be constructed on both thick and soft clay layers, and so the accurate evaluation of magnitude of settlement is required at every step in design and construction. Especially, secondary compression may play an important role in consolidation settlements of soft clay. Generally, the magnitudes of secondary compression are evaluated by laboratory and in-situ consolidation tests. The empirical $C_a/C_c$ may be economical, fast and powerful tool in estimating secondary consolidation settlement. However, the databases of the $C_a/C_c$ at construction site in Korea are insufficient. The purpose of this study is to investigate the relationship of $C_a/C_c$ on marine clay near the southern sea in Korea. A series of incremental loading consolidation tests (measuring base pore water pressure) is peformed. It was found that the $C_a/C_c$ on undisturbed marine clay is 0.0397.

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Excessive Settlement Back-Analysis of Railway Embankment on Soft Soils during Service

  • Ahn, Taebong
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.1
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    • pp.13-17
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    • 2019
  • This paper presents case history of railway embankment excess settlement on soft clay during service in southern region of Korea. A lot of field observations show that the measured settlements are a lot larger than settlements actually calculated in this area. Back analysis is carried out to verify the soil parameters which are intended to investigate in the subsurface exploration phase and later in a laboratory test program. Recommendations and causes for the engineering practice are suggested to review the determination of excess settlements and, consequently, to improve the settlement prediction. This enormous discrepancy is due to the passing over secondary consolidation, and the design filling did not meet to real construction filling. Immediate settlement could be subsidiary factor of excess settlement.

Prediction of Long-term Settlement in the Big Reclamation Site Using GIS (GIS 기법을 이용한 대규모 매립지반의 장기침하 예측)

  • 김홍택;이혁진;김영웅;김진홍;김홍식
    • Journal of the Korean Geotechnical Society
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    • v.18 no.2
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    • pp.107-121
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    • 2002
  • In this study, GIS(Geographic Information System), a new approaching method, is proposed to effectively manage long-term settlements in the big reclamation sites. To verify an applicability of the proposed method, the prediction of long-term settlements which may occur in the overall soft deposits of the Incheon International Airport is carried out. During the process of the prediction of long-term settlements, measured settlement data obtained from an early stage of preloading are analyzed in detail. For purposes of the analysis, an estimation of the recompression index is also made based on the Nagaraj's research results. The coefficient of the secondary consolidation is further determined based on the relationship presented by the Mesri & Godlewski, which defines a ratio between the coefficient of the secondary consolidation and the recompression index.

$C_a/C_c$ for Marine Clay at Southern Part of Korea (남해안 해성점토의 $C_a/C_c$)

  • 김규선;임형덕;이우진
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.03a
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    • pp.373-380
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    • 1999
  • Consolidation settlements of soft clay are often large and potentially damaging to the structures. Currently, large-scale construction projects for airport and harbor etc. are in progress in Korea and many of these structures will be constructed on thick and soft clay layers. For this kind of ground condition, evaluation of consolidation settlement is required at every design and construction stages, and the magnitude of secondary compression appears to be larger than expected. Generally, the magnitude of secondary compression is evaluated by laboratory and in-situ consolidation tests or by empirical $C_{a/}$ $C_{c}$, relationship. The use of empirical value $C_{a/}$ $C_{c}$ may be economical, fast and powerful tool in estimating secondary consolidation settlement. However, the databases of the $C_{a/}$ $C_{c}$, for typical soft clays in Korea are insufficient. The purpose of this study is to investigate the relationship of $C_{a/}$ $C_{c}$ on marine clay near the southern sea in Korea. A series of incremental loading consolidation tests with measurement of pore water pressure were performed. It was found that the $C_{a/}$ $C_{c}$ of undisturbed marine clay is 0.0397. This value is similar to that proposed by Mesri and Castro(1987) on inorganic clay and silt. and silt. and silt.

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Long-term Consolidation Characteristics of Busan Clay considering OC or NC States (과압밀 및 정규압밀영역의 응력상태에 따른 부산점토 장기압밀특성)

  • Kim, Yun-Tae;Jo, Sang-Chan
    • Journal of Ocean Engineering and Technology
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    • v.25 no.6
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    • pp.110-115
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    • 2011
  • Numerouslong-term consolidation and secondary compression settlements may occur in Busan clay, which is astructured soft clay and consists of a thick clay deposit. As a surcharge load is applied to soils, soils experience different stress paths with depth. Therefore, it is necessary to study the long-term consolidation behavior of Busan clay considering stress conditions such as OC or NC states. In this study, a series of long-term consolidation tests were performed to investigate the consolidation characteristics of Busan clay for 20 days. The undisturbed clay samples were taken from 3 sites located in the Nakdong River estuary. The results showed that the creep rate of the Busan clay gradually decreased with time, which indicated that the secondary compression settlement decreased with time. In addition, the experimental results for 3 samples showed that the ratios were about 0.0363 and 0.051, respectively.

Elasto-viscoplastic modeling of the consolidation of Sri Lankan peaty clay

  • Karunawardena, Asiri;Oka, Fusao;Kimoto, Sayuri
    • Geomechanics and Engineering
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    • v.3 no.3
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    • pp.233-254
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    • 2011
  • The consolidation behavior of Sri Lankan peaty clay is analyzed using an elasto-viscoplastic model. The model can describe the secondary compression behavior as a continuous process and it can also account for the effect of structural degradation on the consolidation analysis. The analysis takes into account all the main features involved in the process of peat consolidation, namely, finite strain, variable permeability, and the secondary compression. The material parameters required for the analysis and the procedures to evaluate them, using both standard laboratory and field tests, are explained. Initially, the model performance is assessed by comparing the predicted and the observed peat consolidation behavior under laboratory conditions. The results indicate that the model is capable of predicting the observed creep settlements and the effect of layer thickness on the settlement analysis of peaty clay. Then, the model is applied to predict the consolidation behavior of peaty clay under different field conditions. In this context, firstly, the one-dimensional field consolidation of peaty clay, brought about by the construction of compacted earth fill, is predicted. Then, the two-dimensional peat foundation response upon embankment loading is simulated. A good agreement is seen in the comparison of the predicted results with the field observations.

Geotechnical Engineering Characteristics and Consolidation Settlement Estimation of Waste Lime Landfill (폐석회 매립지반의 지반공학적 특성 및 압밀침하량산정)

  • Shin, Eun-Chul;Lee, Ae-Young
    • Journal of the Korean Geosynthetics Society
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    • v.15 no.4
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    • pp.1-8
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    • 2016
  • The purpose of this study is to examine the consolidation characteristics of waste landfill from sodium carbonate production. The waste lime is a byproduct from the production of soda ash. The consolidation settlement of waste lime landfill was determined for waste lime specimen which obtained from the field boring. The consolidation tests are conducted for determination of the primary and secondary consolidation settlements. The waste lime is classified as an organic soil with high plasticity. As a result of an organic content test, the contents of organic matter in waste lime is much higher than that of normal clay. Finally, the total consolidation settlement of waste lime landfill is calculated by using a theoretical method and computer program for the given initial void ratio, compression index, and embankment height.