• Title/Summary/Keyword: Sand compaction piles(SCP)

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Comparison Study on Stress Sharing Characteristics of Sand or Gravel Compaction Piles with Low Replacement Area Ratio (모래와 쇄석을 이용한 저치환율 다짐말뚝공법의 응력분담특성에 관한 비교)

  • You, Seung-Kyong;Cho, Sung-Min;Kim, Ji-Yong;Shim, Min-Bo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.443-452
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    • 2005
  • The compaction pile methods with low replacement area ratio used sand(SCP) or gravel(GCP) has been usually applied to improvement of soft clay deposits. In order to design accurately compaction pile method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP and GCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which and elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And,through the results of the numerical analyses, each mechanical behaviors of compaction piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between compaction piles and clays.

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Experimental Study on Stress Sharing Behavior of Composition Ground Improved by Sand Compaction Piles with Low Replacement Area Ratio (저치환율 모래다짐말뚝에 의한 복합지반의 응력분담거동에 대한 실험적 연구)

  • 유승경
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.253-261
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    • 2003
  • Mechanical behavior of composition pound improved by sand compaction pile (SCP) with low replacement area ratio could be more significantly affected by mechanical interaction between sand piles and clays than that of clay ground improved by SD or SCP with high replacement area ratio. It is essential to elucidate the mechanical interaction in the improved clay ground, in order to accurately estimate behavior in reducing settlement of the improved ground and increasing strength of clays. In this paper, through a series of model tests of composition ground improved by SCP with low replacement area ratio, each mechanical behaviors of sand piles and clays in the composition ground during consolidation was elucidated, together with stress sharing behavior between sand piles and clays.

Stress Sharing Behaviors and its Mechanism During Consolidation Process of Composition Ground Improved by Sand Compaction Piles with Low Replacement Area Ratio (저치환율 SCP에 의한 복합지반의 압밀 과정중에 발생하는 응력분담거동과 그 메커니즘)

  • 유승경
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.301-310
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    • 2003
  • In order to design accurately sand compaction pile (SCP) method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And, through the results of the numerical analyses, each mechanical behavior of sand piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between sand piles and clays.

Study on Stress Sharing Mechanism Composition Ground Improved by SCP with Low Replacement Area Ratio (저치환율 SCP에 의한 복합지반의 응력분담 메커니즘에 관한 연구)

  • You, Seung-Kyong;Matsui, Tamotsu;Hong, Won-Pyo;Yoon, Gil-Lim
    • Proceedings of the Korean Geotechical Society Conference
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    • 2004.03b
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    • pp.197-202
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    • 2004
  • In order to design accurately sand compaction pile (SCP) method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And, through the results of the numerical analyses, each mechanical behaviors of sand piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between sand piles and clays.

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Behavior of Soft Ground Treated with Sand Compaction Piles and Sheet Piles (모래다짐말뚝과 널말뚝으로 처리된 연약점토지반의 거동)

  • Yoo, Nam-Jae;Jeong, Gil-Soo;Park, Byung-Soo;Kim, Kyung-Soo
    • Journal of Industrial Technology
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    • v.26 no.B
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    • pp.93-99
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    • 2006
  • Centrifuge model experiments were performed to investigate the confining effects of the sheet piles, installed to the sides of soft clay ground treated with sand compaction piles, on the bearing capacity and concentration ratio of composite ground. For the given g-level in the centrifuge model tests, replacement ratio of SCP and the width of surcharge loads on the surface of ground with SCP, the confining effects of installing the sheet piles on the edges of SCP ground on the bearing capacity, change of stress concentration ratio and failure mechanism were investigated. Kaolin, one of typical clay mineral, and Jumunjin standard sand were used as a soft clay ground and sand compaction pile irrespectively. As results of experiments, lateral confining effect by inserting the model sheet piles fixed to the loading plate was observed. For the strip surcharge loading condition, the yielding stress intensity in the form of the strip surcharge loads tends to increase with increasing the embedded depth of sheet piles. The stress concentration ratio was found not to be influenced consistently with the embedded depth of sheet piles whereas the effect of stress intensity on stress concentration ratio shows the general trend that values of stress concentration ratio are relatively high at the initial stage of loading and tend to decrease and converge to the certain values. For the failure mechanism in the case of reinforced with sheet piles, displacement behavior related to the punching failure, settlement right beneath the loading plate occurred since the soil was confined with sheet piles, was observed.

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Characteristics of Bearing Capacity and Stress Concentration of Clay Ground Improved with Sand Compaction Piles (SCP 보강 점성토 지반의 지지력 및 응력분담특성)

  • Yoo Nam-Jae;Park Byung-Soo;Jeong Gil-Soo;Koh Kyung-Hwan;Kim Ji-Sung
    • Journal of the Korean Geotechnical Society
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    • v.21 no.1
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    • pp.81-91
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    • 2005
  • This paper is the results of experimental and numerical works on the investigating design factors influencing the bearing capacity, the ratio of stress concentration, and the failure mechanism of the clay ground improved with sand compaction piles (SCP). In order to find the behavior of the clay ground improved with SCP, extensive centrifuge model experiments were carried out for each of the SCP replacement ratio of 20, 40, and $70\%$, the non-plastic fine contents in sand of 5, 10, and $15\%$, and the ratio of the improved width to the loaded area (W/B) of 1, 2, and 3. The commertially available software of FEM, CRISP, was used to analyze test results by performing numerical estimations. In these numerical analyses the sand compaction piles and the clay ground were simulated as a linear elastic and plastic constitutive model and the modified Cam-clay model, based on Critical State Soil Mechanics, respectively.

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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Effect of performance method of sand compaction piles on the mechanical behavior of reinforced soft clay

  • Kwon, Jeonggeun;Kim, Changyoung;Im, Jong-Chul;Yoo, Jae-won
    • Geomechanics and Engineering
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    • v.14 no.2
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    • pp.175-185
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    • 2018
  • Sand Compaction Piles (SCPs) are constructed by feeding and compacting sand into soft clay ground. Sand piles have been installed with irregular cross-sectional shapes, and mixtures of both sand and clay, which violate the design requirement of circular shape according to the replacement area ratio due to various factors, including side flow pressure. Therefore, design assumptions cannot be satisfied according to the conditions of the ground and construction and the replacement area ratio. Two case histories were collected, examined, and interpreted in order to study the effect of the shape of SCPs. The effects of the distortion of SCP shape and the mixture of sand and clay were studied with the results of large direct shear tests. The design internal friction angle was secured with the irregular cross-sectional sand piles regardless of the replacement area ratio. The design internal friction angle was secured regardless of mixed condition when the mixture of sand and clay was higher than the replacement area ratio of 65%. Therefore, systematic construction management is recommended with a replacement area ratio below 65%.

A Study on a Compression Index for Settlement Analysis of SCP Treated Ground Using Back Analysis (역해석을 이용한 모래다짐말뚝(SCP)으로 개량된 연약점토지반의 압축지수 결정에 관한 연구)

  • Hwang, Sungpil;Im, Jongchul;Kwon, Jeonggeun;Kang, Yeounike;Joo, Ingon
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.7
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    • pp.5-14
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    • 2010
  • The paper processed settlement analysis using Finite Elements Method(FEM). Because Stress Distribution Ratio has to be decreased, for settlement analysis of soft clay deposit improved by sand compaction piles(SCP). Back analysis was processed comparing the measured settlements of laboratory model tests and finite element analysis where the SCP treated area was assumed as mixed ground with clay deposit rather than being a composite ground. The paper proposes a methodology which employs a compression index($C_c$) for settlement analysis of soft clay deposit improved by sand compaction piles from the back analysis. This approach is applied to a field measurement case(A revetment founded on the SCP improved clay deposit with the replacement ratio of 45%).

Characteristics of Settlement and Bearing Capacity of Soft Ground Improved by Granular Pile (Granular Pile에 의해 개량된 연약지반의 지지력 및 침하특성)

  • 천병식;여유현
    • Proceedings of the KSR Conference
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    • 2002.05a
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    • pp.289-294
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    • 2002
  • Sand Compaction Pile (SCP) method, which uses sand material, is frequently used in Korea. However, the use of sand for SCP faces environmental and economical problems with the shortage of its resources. Therefore, it is necessary to substitute other materials for compaction piles. One of the alternatives is using gravel in lieu of sand. Granular Pile, constituted with sand and crushed-stone, is one of the methods to improve soft clay and loose sandy ground. In this study, modeled pile load tests are performed in test cell. The observations are made on the consolidation and the variation of water table of three different grounds, original, sand pile installed, and granular pile installed ground. In addition, engineering characteristics such as bearing capacity, settlement and drainage are investigated. The test results show that Gravel Compaction Pile (GCP) is more efficient for increasing bearing capacity and reducing settlement than SCP and had similar pore water pressure dissipation to sand. Therefore, the results show that GCP can be a good substitution for SCP.

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