• 한국농공학회지
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• 제20권4호
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• pp.4805-4811
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• 1978

This paper deals with the correlations between the results of the physical property tests and the mechanical property tests for estimating the mechanical indexes by the physical property test results. The soil samples were taken at changweon area, Gyeon-gsangnam-do, where the structures would be placed on the alluvial clay foundation. The outcomes of the study are as follows: 1. Judging from casagrande's plasticity chart, it is considered that the almost all soil samples belong to inorganic silty clay with medium plasticity (clay 14∼62%, silt 36∼73%, sand 1∼29%). The specific gravities are between 2.61 and 2.72, the wet unit weights 1.53g/㎤ and 1.93g/㎤, the liquid limits 28% and 51%, the plastic limits 15% and 31%, the plastic indexes 7% and 27%, the natural moisture contents 33% and 64%. 2. The unconfined compression strengths are between 0.07kg/$\textrm{cm}^2$ and 0.77kg/$\textrm{cm}^2$, the cohesions 0.04kg/$\textrm{cm}^2$ and 0.37kg/$\textrm{cm}^2$, the internal friction angles 0$^{\circ}$ and 9$^{\circ}$. 3. The consolidation tests show that the initial void ratios are between 0.68 and 1.68, the precompression loads 0.27kg/$\textrm{cm}^2$ and 1.15kg/$\textrm{cm}^2$, the compression indexes 0.12 and 0.59. 4. The correlations between the results of the physical property tests and the mechanical property tests for the soil samples are presented as follows: rt=0.011 (203-wn), Cc=0.025 (LL-27.2), Cc=0.46 (e0-0.58), Cc=0.013 (wn-23.2), C=0.021+qu/2.08, qu=2.268rt-3.635

• 한국지반환경공학회 논문집
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• 제22권6호
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• pp.17-26
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• 2021

일반적으로 각종 구조물 등의 침하 또는 안정성 검토 등에 사용하는 지반조사 및 결과분석은 사질토와 점성토에 따라 다르며, 세립토의 경우 주로 흙의 컨시스턴시를 이용하여 지반의 물리적 특성과 흙 분류, 공학적 거동을 평가하고 있다. 가장 일반적으로 액성한계를 분석하는 방법은 Casagrande로 비교적 간단하게 액성한계를 구할 수 있으나 사질토를 함유한 중간적인 성질을 가지는 흙에 적용하기에는 많은 어려움이 발생한다. 본 연구에서는 점토의 액·소성한계를 가지고 압축지수를 추정할 때 세립분 함유율에 따라 액성한계치를 수정하는 방안을 제안하고자 한다. 이를 위해 사질토를 함유한 중간토의 특성을 고려하여 양산, 광양, 부산지역의 점토와 사질토를 혼합한 중간토를 제작하여 컨시스턴시 한계시험을 수행하였으며, 컨시스턴시 보정 제안식을 활용하여 적용성 평가를 하였다. 중간토는 점토와 사질토의 혼합시료로써 중간토 제작을 위해 세립토 함유율(F_c)을 50%, 75%, 100%를 적용하였다. 중간토는 자연 상태의 점토 특성을 재현하기 위해 벤토나이트를 일정 비율로 혼합하여 시료를 성형 한 다음 물리적 특성 시험 및 컨시스턴시 시험을 수행하였으며, 기존 연구에서 제안된 컨시스턴시 보정식과 실험에 의한 컨시스턴시 결과치를 비교·분석하였다. 또한, 현장에서 채취한 시료의 컨시스턴시와 보정 제안식에 의해 수정된 컨시스턴시를 비교·분석하고, 보정된 컨시스턴시 값을 적용하여 사질토가 함유된 중간토의 압축지수 등 공학적 특성을 비교·분석함으로써 제안식의 적용성을 평가하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1115-1123
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• 2008

When constructing projects such as road embankments, bridge approaches, dikes or buildings on soft, compressible soils, significant settlements may occur due to the consolidation of these soils under the superimposed loads. The compressibility of the soil skeleton of a soft clay is influenced by such factors as structure and fabric, stress path, temperature and loading rate. Although it is possible to determine appropriate relations and the corresponding material parameters in the laboratory, it is well known that sample disturbance due to stress release, temperature change and moisture content change can have a profound effect on the compressibility of a clay. The early research of Tezaghi and Casagrande has had a lasting influence on our interpretation of consolidation data. The 24 hour, incremental load, oedometer test has become, more or less, the standard procedure for determining the one-dimensional, stress-strain behavior of clays. An important notion relates to the interpretation of the data is the ore-consolidation pressure ${\sigma}_p$, which is located approximately at the break in the slope on the curve. From a practical point of view, this pressure is usually viewed as corresponding to the maximum past effective stress supported by the soil. Researchers have shown, however, that the value of ${\sigma}_p$ depends on the test procedure. furthermore, owing to sampling disturbance, the results of the laboratory consolidation test must be corrected to better capture the in-situ compressibility characteristics. The corrections apply, strictly speaking, to soils where the relation between strain and effective stress is time independent. An important assumption in Terzaghi's one-dimensional theory of consolidation is that the soil skeleton behaves elastically. On the other hand, Buisman recognized that creep deformations in settlement analysis can be important. this has led to extensions to Terzaghi's theory by various investigators, including the applicant and coworkers. The main object of this study is to suggestion the modified compression index value to predict settlements by back calculating the $C_c$ from different numerical models, which are giving best prediction settlements for multi layers including very thick soft clay.