• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.325-332
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• 2003

In general, soil characteristics are estimated through the sample gathered by field boring without considering sample disturbance. However, soil characteristics must be changed by the degree of sample disturbance. Therefore it be need to estimate the soil characteristic considering sample disturbance which can be occurred by the change of stress condition, sampling technique and handling method. On this study, we analyzed the sample disturbance by using the methods of volume change, residual effective stress, elastic modulus and the curve of consolidation tests. In order to estimate the relationship between sample disturbance and soil characteristics, we used the piston sample and the block sample. As the results, it should be considered in design that the disturbance of the block sample, which affects the strength and compression properties of clay, is smaller than the disturbance of piston sample.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.706-713
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• 2004

This paper introduced an alternative method called USCP (Unpenetrated Sand Compaction Pile). In USCP, the toe of the sand pile does not reach to the lower supporting layer. Hence it is possible to reduce the amount of sand required. However, the degree of improvement could not be the same as SCP. Effective soil improvement, nevertheless, might be possible by combining both methods. In this paper, an improved method that cross over both SCP and USCP was discussed. And in order to verify applicability to a clay layer, consolidation behaviors with different conditions were analyzed and compared using FEM(Finite Element Method) based on the elasto-viscosity theory. From the results, it is concluded for the characteristic of settlement of USCP that the lower degree of replacement and the smaller ratio of penetration($H_d/H$), the larger is the settlement of the lower part of the clay layer comparing to the layer with no improvement. It is also concluded that the ratios of allotment of stress (m) calculated from the final settlements with 30% of degree of replacement are $1.8{\sim}3.3$ for $H_d/H=lOO%,\;1.8{\sim}4.0\;for\;H_d/H=75%,\;and\;1.8{\sim}3.8\;for\;H_d/H=50%$. Besides, the ratio of allotment of stress decreased as the degree of replacement decreased.

• 한국지반공학회논문집
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• 제29권3호
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• pp.5-13
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• 2013

압축지수는 점토의 압축특성을 나타내는 대표적인 물성치로 압밀시험으로 직접 결정하거나, 점토의 기본 물성으로부터 경험적 방법으로 추정한다. 그러나 자연점토의 압축지수는 지반 물성치뿐 아니라 퇴적상태에 영향을 받으므로 경험적 추정방법은 지역적 한계를 지닌다. 본 연구에서는 재성형점토의 압축특성을 이용하여 지반 물성치로부터 자연 점토의 압축지수를 추정하는 새로운 방법을 제안하였다. 부산점토의 압밀시험 결과를 통해 제안방법의 적합성을 검증하였으며, 오차원인을 분석하였다. 분석결과 제안된 방법은 경험적 추정방법보다 압축지수를 정확하게 추정하였다. 제안방법의 오차는 가정사항에 의해 발생하며, 추정오차는 $e_{cross}/e_0$와 명확한 반비례 관계를 나타냈다.

• Geomechanics and Engineering
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• 제18권2호
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• pp.189-203
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• 2019

Brine leakage is a common phenomenon during construction facilitated by artificial freezing technique, threatening the stability of frozen wall due to the continual thawing of already frozen domain. This paper takes the frequently encountered soft clay in Wujiang District as the study object, and remolded specimens were prepared by mixing calcium chloride solutions at five levels of concentration. Both the deformation and pore water pressure of frozen specimens during thawing were investigated by two-stage loading tests. Three sections were noted from the changes in the strain rate of specimens during thawing at the first-stage load, i.e., instantaneous, attenuated, and quasi-stable sections. During the second-stage loading, the deformation of post-thawed soils is closely correlated with the dissipation of pore water pressure. Two characteristic indexes were obtained including thaw-settlement coefficient and critical water content. The critical water content increases positively with salt content. The higher water content of soil leads to a larger thaw-settlement coefficient, especially at higher salt contents, based on which an empirical equation was proposed and verified. The normalized pore water pressure during thawing was found to dissipate slower at higher salt contents, with a longer duration to stabilize. Three physical indexes were experimentally determined such as freezing point, heat conductivity and water permeability. The freezing point decreases at higher salt contents, especially as more water is involved, like the changes in heat conductivity. The water permeability maintains within the same order at the considered range of salt contents, like the development of the coefficient of consolidation. The variation of the pore volume distribution also accounts for this.

• 산업기술연구
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• 제20권A호
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• pp.101-111
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• 2000

This research is results of experimental and numerical works on characteristic of strength increase and bearing capacity in dredged and reclaimed soil due to desiccation shrinkage. For a soil sampled from southern coastal area in Korea, basic soil property tests and standard consolidation test with falling head permeability tests were carried out to obtain consolidational characteristics of soil. Double cone penetration test, laboratory vane test and unconfined compression test were also performed to investigate the change of shear strength with degree of desiccation. Model tests were performed in 1G environment and 30G level artificially accelerated condition by using the centrifuge model test facilities to investigate the bearing capacity of desiccated ground. Test results were analyzed by using the theoretical and load-settlement characteristics method proposed by Meyehof & Hanna(1978). On the other hands, the numerical technique, using the finite strain consolidation theory considering the effect of desiccation was used to estimate the appropriate time of using heavy construction equipments in field with respect to strength increase due to desiccation.

• Tuberculosis and Respiratory Diseases
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• 제38권4호
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• pp.401-405
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• 1991

Bronchioloalveolar cell carcinoma accounts for less than 6% of all primary lung cancer but has distinct clinical and radiological features and unusual pathologic appearance. The characteristic features are its peripheral location and tendency of rapid progression to diffuse type via aeroginous and lymphatic route without surgical intervention. Among them, mucin secretory type bronchioloalveolar cell carcinoma is the rarest and most distinctive. We experienced a case of mucin secretory type bronchioloalveolar cell carcinoma in a 47 year old female with roentgenographic findings of chronic progressive pulmonary consolidation with muliple cavities.

• 한국지반공학회논문집
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• 제19권5호
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• pp.311-317
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• 2003

일정변형속도 압밀시험(CRS)을 이용하여 점성토의 팽창지수 산정 특성을 조사하였다. CRS압밀시험에서 재하단계의 변형률은 0.05%/min와 0.03%/min을 적용하였으며, 재하단계에서는 재하단계의 변형속도의 1/1, l/5, 1/10, 1/15에 해당하는 변형속도를 적용하였다. 표준압밀시험과 비교하여 팽창지수를 산정한 결과 1/5∼1/10정도의 변형속도를 적용했을 때 서로 유사한 팽창지수가 산정되었다. 또한, 유효응력과 과잉간극수압비의 관계에서 교차점이 존재함을 알았으며 이 교차점을 기준으로 변형속도에 의존적인 부분과 비의존적인 부분이 존재함을 알 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1039-1046
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• 2005

After clay particles have been sediment isotropically, the clay deposits have been consolidated under $K_0$-stress system. Therefore, in order to predict the behavior in-situ of normally consolidated clays, the laboratory test should be enforced under $K_0$-stress system and should obtain the characteristics of normally consolidated clays. And relationship of stress-strain on clay is effected on not only method of consolidation but also characteristic of visco-plastic behavior. Saturated clay is effected more this trend. So, rate of strain is considered to understand exact stress-strain relationship. In this study, the series of undrained triaxial compression tests were preformed on remolded specimens which was made by slurry of clay, consolidated under $K_0$-stress systems. And the undrained triaxial compression test were preformed to examine behavior of stress-strain relationship due to rate of shear strain relationship due to rate of shear strain.

• 대한금속재료학회지
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• 제47권10호
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• pp.660-666
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• 2009

The consolidation of mechanical alloyed $Ti_5Si_3$ powder by electro-discharge-sintering has been investigated. A single pulse of 2.5 to 8.0 kJ/0.34 g was applied to each powder mixture using 300 and $450{\mu}F$ capacitors. A bulk-like solid with $Ti_5Si_3$ phase has been successfully fabricated by the discharge with an input energy of more than 2.5 kJ in less than $160{\mu}sec$. Micro-Vickers hardness was found to be higher than 1350, which is significantly higher than that of a conventional high temperature sintered sample. The formation of $Ti_5Si_3$ and consolidation occurred through a fast solid state diffusion reaction.

• Geomechanics and Engineering
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• 제27권6호
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• pp.595-604
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• 2021

With the advantages of high permeability and strength, pervious concrete piles can be suitable for ground improvement with high water content and low bearing capacity. By comparing the strength and permeability of pervious concrete with different aggregate sizes (3-5 mm and 4-6 mm) and porosities (20%, 25%, 30% and 35%), the recommended aggregate size (3-5 mm) and porosity (30%) can be achieved. The model tests of the pervious concrete piles in soft soil (silt and clay) foundations were conducted to evaluate the bearing characteristics, results show that, for the higher consolidation efficiency of the silty foundation, the bearing capacity of the silty foundation is 16% higher, and the pile-soil stress ratio is smaller. But when it is the ultimate load for the piles, they will penetrate into the underlying layer, which reduces the pile-soil stress ratios. With higher skin friction of the pile in the silty foundation, the pile penetration is smaller, so the decrease of the pile axial force can be less. For the difference in consolidation efficiency, the skin friction of pile in silt is more affected by the effective stress of soil, while the skin friction of pile in clay is more affected by the lateral stress. When the load reaches 4400 N, the skin friction of the pile in the silty foundation is about 35% higher than that of the clay foundation.