• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.2
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• pp.86-95
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• 2003

During this study, constant stress ratio tests with previous compression anisotropic stress history are performed on compacted decomposed granite soil sampled at Iksan, Jeonbuk. Yielding points are determined from stress-strain curves. The shape and characteristics of compression anisotropic yield curves is examined. In addition, the measured value of yielding curve and stress-strain behavior is predicted by Yasufuku's anisotropic constitutive model based on non-associated flow rule. The main results are summarized as follows : 1) Shape of yielding curves shows almost ellipse but asymmetry with respect to stress path during previous consolidation stress. 2) Yasufuku's anisotropic constitutive model is suitable in evaluation of yielding curves on anisotropic consolidated decomposed granite soil. 3) The predicted stress-strain curve shows reasonable agreement to measured behaviours.

• Geotechnical Engineering
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• v.11 no.1
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• pp.41-50
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• 1995

In situ clay soils with Ko condition have anisotropic characteristics, varying the response according to the principal stress direction upon loading. But because of their practicality and simplicity, consolidated isotropic undrained compression tests are commonly used in practice to determine the behavior of cohesive soils. In this study to investigate the anisotropic characteristics and the effects of consolidation stress states on the response of normally consolidated clay soils during shearing, triaxial compression and extension tests after consolidating the undisturbed clay soil samples, which are obtained as a block sample to normalized consolidation states under isotropic or Ko state, were carried out. As a result of tests, the anisotropy of the undrained strength was confirmed. Comparing the soil responses between isotropic and Ko consolidation, the undrained strength by isotropic consolidation is overestimated because of its higher mean consolidation pressure. And isotropic consolidation reduces the anisotropy of soil response and influences on the stress-strain behavior and pore pressure response because the animotropic soil structure is partially collapsed during isotropic consolidation process. Also, OCR in overconsolidated soils is decreased by isotropic consolidatiorL Friction angle in eztension is higher than that in compression, but regression analysis shows that friction angle with cohesion in extension is almost the same as that without cohesion in compresslon.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.216-223
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• 2005

The coefficient of consolidation has been evaluated using the conventional oedometer tests based on the one-dimensional consolidation theory. In the field, however, the actual response of the soil will be subject to the three-dimensional condition during consolidation. In this research, a new estimation method of the coefficient of consolidation for the various stress-deformation conditions was proposed. The good agreement between the computed dissipation of pore pressure and the measured data confirms the usefulness and the applicability of the proposed method to predict the exact rate of consolidation.

• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.5-17
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• 2003

Using Rowe cell for vertical and lateral consolidate test, we concerned characteristics of vertical and lateral consolidation, and permeability on the remolded Decompoed Mudstone Soil in Phoang, and then, compared it with Oedometer test results. Indirect coefficients of permeability were calculated by the results of the coefficient of consolidation that were derived from 9 different kinds of methods. The values of indirect coefficients of permeability derived from ${\sqrt{t}}$ method and hyperbolic method were similar to the results of direct coefficients of permeability with respect to vertical drainage, but, in the case of lateral drainage, for all kinds of methods, the values of indirect coefficients of permeability showed overestimated ones. With vertical and lateral direct coefficient of permeability, by investigating the anisotropic effect with respect to permeability on Decomposed mudstone soil, we obtained average value, 13, with respect to anisotropic characteristics for all kinds of consolidation loadings.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.399-406
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• 2000

In this study, using the CRS consolidation tests on reconstituted marine clay, the characteristics of C$\sub$v/, k, e and $\varepsilon$, the anisotropic characteristics of specimen according to the rate of strain were estimated. Also, the validity of the Wissa et al.(1971) consolidation theory on CRS(Constant Rate of Strain) consolidation tests were reviewed. From that results, it was shown that the value of C$\sub$v/, k and u$\sub$b/ was increased as the rate of strain was increased. While the difference of the value( C$\sub$v/, k and u$\sub$b/) between vertically reconstituted specimen and horizontally reconstituted specimen became small as the rate of strain was increased. It is known that k is different due to the hydraulic gradient(i) during the CRS consolidation tests. The subject of this study is to distinguish steady state from transient state in CRS consolidation tests. Consequently, the difference of the value(C$\sub$v/ and k) is higher in case of vertically reconstituted specimen than horizontally reconstituted specimen.

• Geotechnical Engineering
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• v.3 no.1
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• pp.77-96
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• 1987

Based on observation emerged from the undrained tests and the anisotropic consolidation tests, an incremental stress-strain theory for rockfill is proposed in a manner similar to that developed ky Cambridge Group for normally consolidated soils; the volumetric strain due to stress increment is the same as the increment due to an undrained component followed by an increment along the constant stress ratio path. The strains in drained tests are predicted from those in the undrained tests and in the anisotropic consolidation tests. An expression for the undrained stress path is derived based on the bilinear relationship between the pore pressure developed and the stress ratio observed during untrained tests. Good agreement is found between the calculated and measured strains. This trend in behaviour would be helpful in establishing a stress.strain model for rockfill using the elasto-plastic behaviour with the concept of plastic potentials and flow rules.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.303-310
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• 2000

A new stress path testing scheme with back pressure equalization process is proposed, to compute the settlement of clay soils based on their probable deformation mode. The proposed testing scheme minimizes the efforts for testing, otherwise numerous testing works are required to simulate the probable stress paths in the field. Furthermore, the proposed testing scheme can supply anisotropic stress paths for consolidation which cannot be possible in a conventional way. The validity and effectiveness of the proposed testing scheme was investigated and confirmed with test results on remolded kaolinite clay soils. Conclusively, it is suggested that the proposed testing scheme is a very effective tool to compute settlement of clay soils and it is also very useful to investigate the anisotropic characteristics of deformation of clay soils.

• Journal of the Korean Geotechnical Society
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• v.17 no.5
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• pp.173-180
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• 2001

이방압밀이 실트질모래의 정적재하에 의한 유동파괴거동에 미치는 영향을 연구하기 위하여 비배수삼축압축시험을 수행하였다. 이를 위하여 상대밀도가 약 17%인 공시체를 습윤다짐방법에 의해서 성형하고 4가지의 압밀응력비, 1.0, 0.7, 0.55, $K_{o}$ 로서 압밀시켰다. 시험결과로서 정상상태선은 p-q 공간상에서 압밀응력비에 관계없이 유일한 직선이며 collapse line의 기울기는 압밀응력비가 증가함에 따라 선형적으로 감소한다는 사실을 보여준다. 또한, 유동파괴거동을 보이는 느슨하게 다져진 실트질모래의 잔류강도($S_{us}$ )와 첨두강도($S^{p}$ )와의 관계는 압밀응력비의 크기에 관계없이 $S_{p}$ /$p_{c}$ = $A_{L}$ +$B_{L}$ ($S_{us}$ /$p_{c}$ )로 표현되는 일반식으로 나타낼 수 있으며 계수 $A_{L}$ 및 $B_{L}$은 압밀응력비의 크기에 따라 선형적으로 변하는 경향을 나타낸다.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.25-32
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• 2005

The coefficient of consolidation has been evaluated using the conventional oedometer tests based on the one-dimensional consolidation theory. In the field, however, the actual response of the soil will be subject to the three-dimensional condition during consolidation. In this research, a new method f3r estimating the coefficient of consolidation for various stress-deformation conditions was proposed. The good agreement between the computed dissipation of pore pressure and the measured data confirms the usefulness and the applicability of the proposed method to predict the exact rate of consolidation.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.39-41
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• 2004

The engineering properties of the geomaterial, an essential material in construction engineering, are significantly influenced by consolidation mode, which is called inherent anisotropy. Speically cohesive soils feature the anisotropy mainly due to their flate-like minerals and chemical interactions. In this research, an experimental study was conducted for the investigation of the anisoropy. Three isotropic and four anisotropic consolidated-undrained triaxial compression tests were performed for the cohesive specimens with various stress ratios of consolidation. The effects of the consolidation mode for cohesive soils were presented and investigated in stress-strain behavior, pore water pressure, and undrained shear strength of the test results.