• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.455-462
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• 2002

There exist several kinds of continuous consolidation tests to analyze the consolidation behavior of soft clay. The constant rate of strain (CRS) test has been adopted as a standard method by several countries, and some researches also have been peformed by domestic researchers. Among those, the constant pressure ratio (CPR) test is peformed with the constant ratio of excess porewater pressure to vertical effective stress. The test has the advantage of considerable reduction of duration time. In the study, the consolidation characteristics are analyzed by performing the CPR test as validate the pressure ratio with undisturbed soft clay and remolded clay, Also, results of the standard consolidation test and CRS test are compared to verify the CPR test can be employed for practical use. As a result, effects of variation of the pressure ratio on consolidation parameter are similar to the strain rate in the CRS test. Therefore, the test can be used to analyze the consolidation behavior of soft clay But the test have some problems such as expensive cost of equipment and highly skilled workmanship.

• 한국농공학회지
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• 제18권4호
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• pp.4242-4250
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• 1976

The determination of the pre-consolidation load known to have a great effect on the consolidation characteristics of the soil have been researched and discussed in detail by many other researchers. A study was undertaken to investigate and compare the effect of pre-consolidation loads on the coefficient of permeability and the consolidation characterisics of soil through the consolidation test on the three types of soil samples. The results of this study are follows; 1. Large compression index is dependent on initial void ratio of the sample being used and the pressure-void ratio curve shows a curved linear relationship in over-consolidated area but a linear relationship in normally consolidated area.2. Settlement-time curve is S-shaped where the pressure is larger than pre-consolidation load and regardless of over-burden pressure, it is a similar straight line respectively in the secondary consolidation area. 3. Primary consolidation ratio of the sample increases almost linearly with the increase of over-burden pressure but the coefficient of volume compressibility decreases linearly with the increase of it. 4. Time factor of a certain degree of consolidation increases with over-burden pressure but the coefficient of consolidation decreases with it in over-consolidated area. There is a linear relationship between them in normally consolidated area. 5. The void ratio of completion point of primary consolidation decreases linearly with over-burden pressure. 6. The coefficient of permeability of sample decreases linearly with over-burden pressure in normally consolidated area, also it increases linearly with increment of the void ratio of the sample.

• 한국지반공학회지:지반
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• 제12권6호
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• pp.153-162
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• 1996

이방압밀이 과압밀점토의 비배수크리프파괴거동에 미치는 영향을 연구하기 위하여 등방 및 이방과압일시킨 점토시료에 대해서 비배수상태에서 크리프시험을 수행하였다. 연구결과 비배수 크리프파괴거동은 점토시료의 응력이력 즉 과압밀비와 압밀응력비$(\sigma_{3c}/\sigma_{le})$의 크기에 의해서 영향을 크게 받는다는 사실이 밝혀졌다. 즉 점토의 크리프강도는 과압밀비와 압밀응력비가 클수록 증가하므로 정지토압계수가 1.0보다 작은 점토지반의 크리프파괴 가능성을 등방압밀크리프피 괴시험에 의해서 판단하는 것은 위험하다. 그리고 점토의 크리프강도는 과압밀비와 압밀응력비의 크기에 관계없이 Finn과 Shead(1973)의 제안식에 의한 상한항복강도로서 구할 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.3-14
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• 2000

Anisotropic consolidation, shear, a transportational component during or after deposition each may produce anisotropic fabrics, which result in the anisotropic properties of soils. Nevertheless, the isotropically consolidated compression triaxial tests are commonly used in practice to determine the strength of the anisotropically consolidated soils because of their practicality and simplicity. In this paper the effects of anisotropic consolidation on the strength properties of soils are discussed. For the sandy soils consolidated under a constant vertical consolidation pressure, the deformation modulus decreases with decreasing consolidation pressure ratio($\sigma$$\sub$3c/'/$\sigma$ sub 1c/'), but the liquefaction resistance increases. For the saturated cohesive soils, both the undrained shear strength and undrained creep strength decrese with decreasing the consolidation pressure ratio. When the in-situ strength properties of the anisotropically and normally consolidated soils are determined by the isotropically consolidated tests, the undrained shear strength and creep strength of saturated cohesive soils as well as the deformation modulus of sandy soils are measured to be higher than the rear in-situ values. This, therefore, could lead to a dangerous judgement in stability analysis

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.271-276
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• 2002

Continuous loading is applied the sample has been developed to overcome some of the problems associated with the incremental loading consolidation test. Therefore, it is able to reduce the test time and provide a well defined the curve of effective stress versus strain due to continuous stress-strain points. Also, the constant rate of strain consolidation(CRSC) test has been accepted widely as a standard method in foreign countries because of its many advantages. However, in Korea the CRSC test has not been used in engineering practice and experimentally verified. Because there is not a precise criterion of testing despite consolidation characteristics are influenced on strain rate and Pore pressure ratio. Consequently, it is difficult to apply in engineering practice. In this study, artificial neural networks are applied to the estimation of th proper strain rate and pore pressure ratio of the CRSC test. This study shows the possibility of utilizing the artificial neural networks model of estimation of the strain rate and pore pressure ratio in the CRSC test.

• 한국농공학회논문집
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• 제52권2호
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• pp.1-9
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• 2010

This study was carried out to comparison of coefficient of consolidation and the prediction of excess pore water pressure in agricultural reservoir on soft clay ground. For the purpose of verification of the proposed equation, laboratory model tests and field tests were performed and excess pore water pressure was compared to those predicted with the Terzaghi's method. The predicted excess pore water pressure according to ponding was very applicable to practice because it was close to the observed data. Also, for the comparison of coefficient of consolidation, the oedometer, constant rate of strain (CRS), and Rowe cell tests were performed. The coefficient of consolidation at the Rowe cell and CRS tests showed a greate increase than in the oedometer test. The ratio of the vertical and horizontal coefficient of consolidation showed a large difference according to various tests method and mixing ratio. Therefore, it is recommended that careful attention should be paid to predicting the required consolidation period in agricultural reservoir.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1070-1077
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• 2005

The purpose of this study is to establish a proper criterion for the constant rate of loading consolidation(CRLC) test which is a kind of the continuous loading consolidation(CLC) and widely used as alternative methods to the incremental loading consolidation(ILC)test. With those results, the preconsolidation pressure estimated by the CRLC test turned out to be comparatively larger than that of the ILC test, and it is increased in proportion to the applied loading rates. However, the compression index in the CRLC test is less influenced on by the loading rates. The coefficient of consolidation and permeability in the CRLC test are dependent on excess pore pressure ratio mainly. In other words, if the pore pressure ratios are too low, the coefficient of consolidation and permeability become smaller than those of the ILC test. On the other hand, if the excess pore pressure ratios are too high, the coefficient of consolidation and permeability become so larger than those of the ILC test. Therefore, loading rates should be carefully determined to generate proper excess pore pressure ratio inside the soil specimen. From this study, good results are obtained from the CRLC test if the excess pore pressure ratios were in the range of 2.5 to 6.0 %, performed with loading rates between 0.0015 and 0.005 $kgf/cm^2/min$.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.393-399
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• 2003

This paper describes a proper criterion for the constant rate of loading consolidation (CRLC) test which is a kind of the continuous loading consolidation(CRLS) and widely used as alternative methods to the incremental loading consolidation(ILC)test. With those results, the preconsolidation pressure estimated by the CRLC test turned out to be comparatively larger than that of the ILC test and it is increased in proportion to the applied loading rates. However, the compression index in the CRLC test is less ifluenced on by the loading rates. The coeffcient of consolidation and permeability in the CRLC test are dependent on excess pore pressure ratio mainly. In other words, if the pore pressure ratios are too low, the coefficient of consolidation and permeability become smaller than those of the ILC test. On the other hand, if the excess pore pressure ratios are too high, the coefficient of consolidation and permeability become so larger than those of the ILC test. Therefore loading rates should be carefully determined to generate proper excess pore pressure ratio.

• 한국농공학회지
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• 제13권4호
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• pp.2445-2455
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• 1971

One-dimensional Consolidation tests with pore pressure measurement were caried in the ANTE-US consolidometer in order to investigate the effects of loading conditions on consolidation behavior of the soft clay. Undisturbed specimens of a sensitive clay were loaded in load-increment ratioes 0.5, 1.0 and 2.0, and load increment duration of 1, 6, 12, 24 and 48 hours with the application of 40 psi of back pressure. There is no significant effect of load-increment ratio on compression-pressure relationship, but the test with one-hour load increment duration doesn't represent the same results of the standard consolidation test in the sensitive clay.

• 대한토목학회논문집
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• 제28권1C호
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• pp.9-17
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• 2008

본 연구에서는 압밀 중에 위치별 간극수압의 측정을 통하여 시료 내 여러 위치에서 투수계수를 산정할 수 있는 이론해를 제시하였으며, 이를 바탕으로 간극비 및 체적압축계수를 산정할 수 있는 방법을 제안하였다. 또한 여러 위치에서 간극수압을 측정할 수 있는 방사내측배수가 가능한 대형압밀시험기를 제작하고 카올리나이트를 이용하여 압밀시험을 실시하였다. 시험결과로부터 압밀 중 투수계수, 간극비, 체적압축계수의 변화 및 시료 내 위치별 분포를 평가하였으며, 압밀완료 후 시료의 함수비 측정으로 평가된 값들과의 비교를 통하여 실험결과의 신뢰성을 검증하였다. 실험결과 투수계수, 체적압축계수, 간극비는 압밀 중 감소하며, 재하단계에 따라서도 감소함을 확인하였다. 또한 그 분포형태는 배수면 근처에서 가장 작고 배수거리에 따라 증가하며 비배수 경계면 근처에서는 오히려 약간 작은 것으로 나타났다.