• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.255-260
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• 1993

The behavior of pure silt was investigated by using an automated triaxial testing device. The stress-strain behavior of silt due to the volume deformation tendency was compared with the behavior of clay prior to failure and behavior at failure under monotonic undrained compression and extension conditions. A pure silica flour was chosen to form samples. The isotropically normally-consolidated samples with 450 kPa of effective mean confining pressure and overconsolidated samples through unloading were tested. Based on the experimental results, it was qualitatively identified that the undrained strength of normally-consolidated silt increases due to its dilatant nature which is not seen in clay. Also the overconsolidated silt shows a significantly different behavior under the monotonic loadings due to the volume deformation tendency.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.141-149
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• 1999

In order to investigate the anisotropy in the coefficient of consolidation of the clay deposit, a series of consolidation tests were carried out on the artificially deposited clay sample by both Rowe-type and conventional consolidometers. The results of the tests showed that the coefficient of consolidation for radially inward drainage by Rowe-type consolidometer was about two times larger than that for vertical drainage by the conventional consolidometer. The smear effect caused by vertical sand drain installation was found to be significant, especially in the overconsolidated region, but smaller with the increase in consolidation pressure.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.3
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• pp.185-192
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• 2003

This study consolidation undrain Triaxial Compression Tests using constant confining pressure in clay that receive preconsolidation stress that is different and, void ratio, pore water pressure coefficient, shear strength compare with another thing theory and studied analyzing change relation of elastic modules. The summary of analysis is follows: If preconsolidation stress increases in same confining stress in relation of preconsolidation stress and deviator stress, deviator stress is proportional and increased. Can know that excess void pressure is proportional and decreases in size of preconsolidation stress in same confining stress state if preconsolidation stress increases preconsolidation stress and relation of excess void pressure. Also, over consolidated state can assume that this is thing by Dilatancy's effect though excess void pressure decreased remarkably. Preconsolidation stress and relation of stress path can know that shear strength degree increases preconsolidation stress increases, and specially, preconsolidation stress was appear in stress path form of overconsolidated state case of clay that receive at 300, 400, 500kPa in 100, 150kPa's deviator stress.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.02a
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• pp.71-78
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• 2000

SHANSEP method involves the consolidation to stresses in excess of the preconsolidation pressure in order to overcome sample disturbance effect. The concept of SHANSEP is based on an approach to laboratory test which attempts to reproduce the in-situ conditions more closely than is possible in routine tests and evaluates normalized strength parameters for the soil as a function of OCR. But SHANSEP method can be applied only to fairly uniform clay deposits, and is unsuitable for a random deposit. In this study, CK/sub o/U triaxial compression test and incremental loading consolidation test were performed for the application of SHANSEP method on Yangsan clay. During the K/sub o/-consolidation, triaxial specimens were consolidated to stress equal to two times the in-situ vertical effective stress. And for overconsolidated condition, the specimens were swelled to a known vertical effective stress in order to have the desired OCR. With the results of CK/sub o/U triaxial compression test using the block samples, the relationship between c/sub u//σ/sub vc/' and OCR on Yangsan clay was established. For evaluating the undrained shear strength of Yangsan clay with depth, CK/sub o/U triaxial compression test was performed using the piston samples taken from Yangsan site. And also undrained shear strength was analyzed from the in-situ test such as Cone Penetration Test(CPT), Dilatometer Test(DMT), and Field Vane Test(FVT) and was compared with that of CK/sub o/U triaxial compression test.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.25.1-33
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• 1995

지반공학 및 지반환경분야에서 문제의 관건은 표층과 흙의 성질에 대한 정보를 정확히 파악하는 것이다. 표층의 상황은 어느 현장이나 공간적으로 그 성질을 달리하므로 기술자의 경험이나 지구통계학을 이용하여 적절한 현장의 상태를 분석하게 된다. 휴스톤대학에 위치한 미국국립시험현장에서 수행한 28개의 콘관입시험을 통해 얻은 자료를 가지고 지구통계학적분석을 하여 비배수 전단강도의 3차원적 형태를 파악하였다. 본 연구를 통하여 지구통계학의 유용함과 현장의 변화가 상당함을 쉽게 이해하게 된다.

• Geotechnical Engineering
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• v.12 no.5
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• pp.17-26
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• 1996

The undrained behavior of Asan marine soil was investigated by using an automated triaxial testing device. The stress-strain behavior at the preand postfailure state of marine soil under undrained compression and eatension conditions was compared with the behavior of pure silt, pure clay and the overall behavior of Asan marine soil was predicted with the modified Camflay model and the bounding surface model. The marine soil sampled in Asan bay area was clayey silts with 70oA silt-30% clay content and the testing samples were prepared in both undisturbed and remolded conditions. All samples are normally consolidated with 400 kPa of effective mean confining pressure and each sample is unloaded to 200, 100, 67 kPa, respectively. And then the shear test was performed with different confining pressure. According to experimental results, there exists an unique failure line whose slope is lower than silt's and higher than clay's. It is identified that the undrained shear strength of normally consolidated samples increases after crossing the phase transformation line because of volume dilation tendency which is not seen in clay. Overconsolidated samples show different soil behavior compared with pure silt due to its tendency of change in volume. It is also found that the overall behavior of Asan marine soil cannot be predicted precisely with the modified Cam-clay model and the bounding surface model.

• Structural Engineering and Mechanics
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• v.33 no.1
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• pp.67-77
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• 2009

The soil response calculation is described, by which, threw the fictive path of stress, the stress-deformation diagrams are determined, considering the nonlinear soil behavior. The calculation are lead incrementally, by which is shown that in the presented soil model (modified Cam Clay), considering the influence of overconsolidated soil pressure OCR, the number of calculation steps may, but not necessarily, have a sufficient influence on the value of failure load and definite soil deformation. The simplicity and the practicalness of the procedure, the enables modeling the complex relations in soil.

• Geotechnical Engineering
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• v.10 no.4
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• pp.167-180
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• 1994

A series of long term consolidation tests were conducted under loading -unloading and loading(pc) -unloading(p.) -reloading(p,) conditions using reconstituted clay in order to investigate the effect of stress history on secondary consolidation characteristics and the applicability of the secondary consolidation model suggested by Bjerrum to overconsolidated clays. According to the test results, the secondary compression settlement affected by the stress history in the first half of experimental period and the coefficient of secondary compression, C‥‥ is dependent on overconsolidation ratio, OCR(p,1 p.), maBium OCR (p./p.), and unloading duration time. Moreover the coefficient of secondary consolidation in the latter half of experimental period Cn is mainly affected by OCR and it gradually reduces with OCR increment. Finally the comparison of the experimental results with the Bjerrum model indicates that the Bjerrum model can be applied beyond certain range of stress history in the overconsolidated clay.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.575-582
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• 2000

The flat Dilatometer test(flat DMT) has been known as an in-situ testing method which is simple and robust to use, and reliable for site stratification and evaluation of soil properties. It was designed and proposed by Marchetti in 1975 to characterize the properties of soils. There are many researches that have been done to evaluate the horizontal coefficient of consolidation from the dissipation test results of flat DMT on normally consolidated and slightly overconsolidated clays. The representative estimation methods of estimating the horizontal consolidation coefficient are DMT-C method which uses a C-reading dissipation curve and DMT-A method which uses a A-reading dissipation curve. This paper represents a comparison analysis of those two methods in obtaining the horizontal coefficients of consolidation. The reference values are also obtained by CPTU and other laboratory tests. The applicability of using flat DMT to characterize the consolidation behavior is also reviewed for two sites. According to the results, DMT-A method is not suitable for silty clays possibly because of the compressibility characteristics. As for the normally consolidated and slightly overconsolidated clays, the results obtained from the two methods are comparable with each other as well as with the laboratory test results.

• Journal of the Korean Geotechnical Society
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• v.21 no.2
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• pp.5-16
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• 2005

Tn this study, model soil deposits are prepared in large test chambers to minimize the scale effects. Also, slurry of mixture containing 50 percent kaolin clay and 50 percent silica has been consolidated to simulate the process of natural soil deposit formation and to reduce the consolidation time. To provide a more detailed description of varying soil properties along the soil profile of model clay deposits and to compare the in-situ test results with those from prototype tests, miniature in-situ tests, including vane shear, piezoprobe, and cone penetration tests were conducted in each of the clay deposits. The current results indicate that consistent soil deposits were prepared for the current and previous test programs. Also, reasonable predicting methods of prototype behavior based on model in-situ test results were suggested in this study by examining differences between the test results from both the model and prototype tests.