• Geomechanics and Engineering
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• 제33권1호
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• pp.113-120
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• 2023

Coastal and offshore structures such as ports and offshore wind farms will often need to be built on fine-grained sediments. Geotechnical properties associated with sediment compressibility are key parameters for marine construction designs especially on soft grounds, which involve clay-mineral dominated fines that can consolidate and settle significantly in response to engineered and environmental loads. We conduct liquid limit tests and 1D consolidation tests with fine-grained soils (silica silt, mica, kaolin and bentonite) and biogenic soils (diatom). The pore fluids for the liquid limit tests include deionized water and a series of brines with NaCl salt concentrations of 0.001 m, 0.01 m, 0.1 m, 0.6 m and 2.0 m, and the pore fluids for the consolidation tests deionized water, 0.01 m, 0.6 m, 2 m. The salt concentrations help the liquid limits of kaolin and bentonite decrease, but those of diatom slightly increase. The silica silt and mica show minimal changes in liquid limit due to salt concentrations. Accordingly, compression indices of soils follow the trend of the liquid limit as the liquid limit determined the initial void ratio of the consolidation test. Diatoms are more likely to be broken than clastic sediments during to loading, and diatom-rich sediment is therefore generally more compressible than clastic-rich sediment.

• Geomechanics and Engineering
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• 제20권6호
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• pp.537-546
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• 2020

Oil and natural gas reserves have been recognised abundantly in clayey rich rock formations in deep costal reservoirs. It is necessary to understand the sedimentary history of those reservoir rocks to well explore these natural resources. This work designs a group of laboratory experiments to mimic the physical process of the sedimentary clay-rich rock formation. It presents characterisation results of the physical properties of the artificial clayey rocks synthesized from illite clay, quartz sand and brine water by high-pressure consolidation tests. Special focus is given on the effects of illite clay content and high-stress consolidation on the physical properties. Multi-step loaded consolidation experiments were carried out with stress up to 35 MPa on mixtures constituting of the illite clay, quartz sand and brine water with five initial illite clay contents (w=85%, 70%, 55%, 40% and 25%). Compressibility and void ratio were characterised throughout the physical compaction process of the mixtures constituting of five illite clay contents and their water permeability was measured as well. Results show that the applied stress induces a great reduction of clayey rock void ratio. Illite clay contents has a significant influence on the compressibility, void ratio and the permeability of the physically synthesized clayey rocks. There is a critical illite clay content w=70% that induces the minimum void ratio in the physically synthesised clayey rocks. The SEM study indicates, in the high-pressure synthesised clayey rocks with high illite clay contents, the illite clay minerals are located in layers and serve as the material matrix, and the quartz minerals fill in the inter-mineral pores or are embedded in the illite clay matrix. The arrangements of the minerals in microscale originate the structural anisotropy of the high-pressure synthesised clayey rock. The test findings can give an intuitive physical understanding of the deep-buried clayey rock basins in energy reservoirs.

• 대한토목학회논문집
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• 제28권6C호
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• pp.349-358
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• 2008

본 연구에서는 고베 공항 해저 충적 점토를 대상으로 한 신뢰성 침하 해석을 위해 각종 입력 물성치의 불확실성을 확률 통계 이론에 근거하여 조사하였고, Terzaghi 압밀 방정식을 목적 함수로 AFOSM 법을 적용하여 파괴 확률을 정식화하였다. 신뢰성 해석 결과, 목표침하량을 평균침하량 ${\pm}10%,\;{\pm}25%$로 설정한 경우, 발생확률은 각각 30~50%, 60%~90%로 나타났다. 이는 대상 지반의 확률변수의 변동계수가 과거의 연구보고 범위 내에 있음을 고려할 때, 목적함수로 Terzaghi 압밀방정식을 이용한 경우 침하량의 허용 오차 범위는 평균침하량 ${\pm}10%$가 적절할 것으로 사료된다. 또한, 감도 분석 결과 해석에 크게 영향을 미치는 인자는 압축 계수, 모델, 압밀 항복 응력의 불명확성으로 나타났다. 이는 정밀도가 높은 사전 침하량의 예측을 위해서는 현장의 응력 변형 조건을 충실하게 반영한 시험을 수행하여 신뢰도가 높은 물성치를 구하는 것이 매우 중요한 것임을 설명한다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 춘계학술강연 및 발표대회강연 및 발표논문 초록집
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• pp.44-44
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• 2006

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2005년도 추계학술강연 및 발표대회강연 및 발표논문 초록집
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• pp.63-63
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• 2005

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2005년도 추계학술강연 및 발표대회강연 및 발표논문 초록집
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• pp.68-69
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• 2005

• 한국재료학회:학술대회논문집
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• 한국재료학회 1997년도 한국재료학회 추계학술발표회
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• pp.97-97
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• 1997

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.235-235
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• 2009

• 보존과학연구
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• 통권16호
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• pp.18-40
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• 1995

Twelve bronze artifacts and silver earring from Kimhae Yangdong-ri Site were treated by B.T.A(Benzotriazole) for the stabilization of copper alloys and impregnated with Incralac for consolidation. Bronze artifacts were analyzed qualitatively by X-rayfluorescence. It was found that elemental composition of bronze artifacts were Cu-Sn-Pbsystem wint some impurities such as Bi, As, Fem Sb, and Ag.

• 한국분말재료학회지
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• 제15권5호
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• pp.378-385
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• 2008

This article presents the successful consolidation of the mixed Co and Diamond powders for a drilling segment by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were analyzed. Homogeneous hardness (Hv 220) and density (97%) of sintered bulks fabricated by MPC were obtained by the new technique, where higher pressure has been employed for short period of time than that of general process. A fine microstructure and homogeneous hardness in the consolidated bulk were observed without cracks. Relatively higher drilling speed of 9.61 cm/min and life time of 6.55 m were found to the MPCed specimens, whereas the value of the specimens fabricated by general process was 11.71 cm/min and 7.96 m, respectively. A substantial improvement of mechanical properties of segment was achieved through this study.