• 한국지반공학회논문집
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• 제20권2호
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• pp.59-66
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• 2004

SCP 개량지반은 연약지반에 타설된 모래말뚝과 주변 연약지반으로 구성된 복합지반을 형성한다. 복합지반에 상재하중이 작용할 경우, SCP쪽으로 반경방향의 흐름에 의하여 시간의존적인 압밀거동이 유발될 뿐만 아니라, SCP와 주변 연약지반 사이에서 강성도 차이로 인하여 응력전이가 유발된다. 본 논문은 SCP 개량지반의 압밀거동에 대한 교란효과의 영향을 고려하기 위하여 원통형 실린더 지반에 대한 수치해석을 수행하였다. 수치해석결과 연약지반의 교란영역은 유효응력-간극수압의 거동, 응력전이기구, 응력분담비에 영향을 줌을 알 수 있었다. 또한 SCP와 점토 사이의 응력전이량은 상부 z/H=0.25에서 가장 크며, 깊이가 증가함에 따라 감소한다. 응력분담비는 상수값이 아니라 압밀과정에 의존하며, 교란영역을 가진 연약지반의 응력분담비는 교란영역이 없는 연약지반의 응력분담비보다 큼을 알 수 있다.

• 한국농공학회지
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• 제44권6호
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• pp.106-114
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• 2002

In this study, the results of a series of consolidation test for undisturbed Ariake clay in Japan were analyzed by three methods, e-log p (e: void ratio, p: consolidation pressure), log e-log p and n-log p (n: porosity). Moreover, the characteristics of each analysis method were studied. For undisturbed Ariake clay, the log o-Log p and the n-log p relationships can be found as two groups of straight lines of different gradients, but both the elastic consolidation and plastic consolidation regions of e-log p relationship are expressed as a curve. In this paper, the porosity of consolidation yield n$\_$y/, consolidation yield stress p$\_$y/, and the gradient of the plastic consolidation region C$\_$p/ were represented by the log e-log p method, and n$\_$c/, P$\_$cn/ and C$\_$cn/ were represented by the n-log p method. The meaning and the relationships of each value were studied, and the interrelationships among compression indices i.e. C$\_$cn/, C$\_$p/ and C$\_$c/ are obtained from each analysis method as a function of initial porosity n$\_$0/.

• 한국지반공학회논문집
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• 제20권8호
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• pp.113-121
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• 2004

본 연구는 사전압밀재하공법에 의해 연약지반을 개량시 재하-제하-재재하와 같은 다양한 응력변화에 의한 2차압밀량을 추정하고자, 일정변형률 압밀시험기(CRS)를 응용한 일정재하시험장치(CLR)와 표준압밀시험기를 이용한 단계 재하시험(IL)에 의해 군산점토의 압밀특성을 비교 고찰하였다. 또한 CRS시험 후 임의 팽창시점에서 재재하시 유효과압밀비에 따른 2차압밀특성과 간극비-유효응력-시간관계 등을 파악하였다. 군산점토는 유효 과압밀비가 클수록 팽창량은 크고 2차압밀 침하량은 작게 발생하고 있으며, 일시에 하중 제거 후, 재하하는 경우에서 2차압밀계수 $C'_{\alpha}$ 는 완속제거시 보다 작게 평가되고, 유효 과압밀비가 1.4이상인 경우는 유사한 값을 제시하고 있다. 재재하시 발생되는 전체침하량을 기준으로 한 2차압밀계수 $C"_{\alpha}$는 경과시간에 따라 비선형적으로 증가하나 최종값은 급속제거시와 비교하여 유사한 값을 제시하고 있다. 간극비 변형속도는 재하시간이 증가할수록 유효 과압밀비에 관계없이 2개의 시험 모두 일정한 선형관계이고, 유효 과압밀비가 증가할수록 작게 나타나고 있다.고 있다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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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.

• 한국지반신소재학회논문집
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• 제11권2호
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• pp.11-20
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• 2012

미관통 SCP공법은 개량 대상지반인 연약점토층 밑에 존재하는 지지층까지 모래말뚝을 관통시키지 않고 미관통 상태 그대로 SCP를 지반 중에 조성하는 공법으로 본 연구에서는 저치환율인 경우 압밀도에 따른 미관통 SCP공법과 관통 SCP 공법을 병용한 복합지반의 압밀침하 거동을 수치해석을 통해 비교 하였다. 본 연구결과 관통 SCP지반의 침하특성은 압밀도에 상관없이 거의 일정하나 미관통 SCP지반의 침하특성은 압밀도가 감소하고 관통율($H_d/H$)이 감소할수록 상부점토지반의 침하량이 더 크게 증가되었다. 또한 미관통 SCP의 하단부에는 응력집중효과가 발휘되지 않았으며 응력분담비는 압밀도에 관계없이 거의 일정한 양상을 보였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.767-772
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• 2003

The clay which transported into a pond under the high water content condition have no effective stress which develop from the starting point of sedimentation and self-weight consolidation. Since sedimentation and self-weight consolidation dependent on self-weight of solids is made progress over a long time, to accelerating it have many advantages in the economic view In this paper, sand spreading method which is one of sedimentation and self-weight consolidation acceleration method is studied through a series of experiments considering the mixing ratio of sand and clay. The test results show that the mixing ratio of clay and sand of 1:0.2 is the biggest rate of consolidation and the pouring at the end point of sedimentation considerably effects on consolidation rate.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.491-498
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• 2002

Dredged and reclaimed soft clays form slurry state which is very high water content and very low shear strength, experience large self-weight consolidation, nonlinear compressibility and permeability phenomenon would take place. In this case, a material functions which represent variety effective stress-void ratio-permeability relation (especially very low effective stress), are should be determined to predict nonlinear finite strain consolidation phenomenon forehand In this study, large slurry consolidometer with a 380mm diameter and a 1400mm height which is able to consolidation and permeability test, was developed to determine material function of very soft clay with a 500% initial water content clay, self-weight consolidation and low stress level consolidation (1Kpa, 3Kpa, 6Kpa, 12Kpa) was conducted and after each consolidation step permeability test also conducted. after final consolidation step, a constant rate of strain consolidation was conducted with undisturbed sample obtained from the large consolidometer. On the above result, material function was determined and laboratory test was modelled to evaluate its validity, numerical analysis on th field was compared to other method.

• 한국지반공학회지:지반
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• 제3권2호
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• pp.41-54
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• 1987

Although natural soil deposits hat.e been consolidated under Ko-stress system, the soil behavior has been predicted in laboratory from the results of tests performed on specimens consolidated under an isotropic stress s).stem. A series of undrained triaxial compression tests are performed on remolded specimens of clay consolidated under both types of stress systems, and the results at.e compared. One dimensional consolidation history induces anisotropy in clalrs, which is called as the stress induced anisotropy. However, if the clays would be reconsolidated under isotropic stress system. the anisotropy of undrained stress비h would be decreased with decrease of overconsolidation ratio. Undrained shear strength of norma]Iy consolidated clay depends on consolidation methods. Both the Rutledge hypothesis and the study of Henkel and Sowa do not agree with the test results obtained in this paper. In addition, a new theory is explained about the relationships between consolidation stresses, water contents and undiained shear strength.

• 산업기술연구
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• 제11권
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• pp.85-98
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• 1991

A numerical study was performed to investigate characteristics of one-dimensional consolidation of soft clay. Results of consolidation tests with the remolded normally consolidation clay of having a very high initial void ratio were analyzed by using the numerical technique of finite difference method based on the finite strain consolidation theory, to evaluate consolidational characteristics of soft clay under surcharges on the top of clay. On the other hand, a numerical parametric study on soft clay consolidated due to its self-weight was also carried out to find its effect on one-dimensional consolidation. Terzaghi's conventional consolidation theory, finite strain consolidation theories with linear and non-linear interpolation of effective stress - void ratio - permeability relation were used to analyze the test results and their results were compared to each other to figure out the difference between them. Therefore, the validity of theories was assessed.

• 한국안전학회지
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• 제23권6호
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• pp.131-137
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• 2008

SCP(Sand Compaction Pile) method that forms a composite ground by driving compacted sand piles into the soft ground. This method is one of the soil improvement techniques for reinforcing and strengthening soft ground deposits. This thesis describes the investigation on the behavior of soft ground reinforced with SCP by low improvement ratio. Direct shear test and consolidation test carried out to verified behavior of composite ground reinforced with SCP. Test results were discussed with reference to the amount of consolidation settlement, variation of shear resistance with area replacement ratio and effect of the stress concentration. And, laboratory model loading test carried out to verified the effect of the location and failure mode of reinforced embankment. Residual shear strength varies with the area replacement and constrict load in the low replacement ratio. Calculated stress concentration ratio overestimate than proposed valve by experimental, theoretical and analytical method. As regards the location, improving right below of the top of the slope was more effective than below of the toe of the slope. This thesis carried out to obtain fundamental information of behavior of the composit ground. Hereafter, centrifuge test that reproduce stress state of the in-situ must be necessary through the further study about pile penetration, reinforce position and construct time.