• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.542-545
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• 2007

The vertical drain method generate the disturbed zone, because the drainage should be penetrated into the in-situ ground. The characteristics of the smear zone generated cause the problems that the coefficient of permeability decreases and the consolidation time anticipated in the design is not properly shortened. In this study, in order to understand such influence, the laboratory test were carried out so as to reasonably determine the coefficient of consolidation in silt. For that procedure, mandrel of a diversity were penetrated into the soil tube with silt, and then the variation of pore water pressure was measured with the pore pressure meter, Then, the range of smear effect on silt was estimated with monitoring data through the laboratory test, and also analyzed with inputting the coefficient of consolidation into the theoretical equation.

• JSTS:Journal of Semiconductor Technology and Science
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• 제2권4호
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• pp.253-258
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• 2002

This paper reports the design, modeling, fabrication and measurement of passive microvalves, which are applicable to glaucoma implants. The proposed microvalves were designed using fluidic theory. The microvalves consisted of microchannels and chambers. The microchannels had a constant fluidic resistance generating a pressure difference. Six kinds of microvalves were designed using fluidic equations for laminar flow and fabricated to examine the influences of chamber size, channel length and the shape of channel cross section. The pressure difference between the designed microvalve and the fabricated microvalve was measured to be less than 4%.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.189-198
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• 2006

This paper concerns the finite element (FE) modeling approach for NATM tunneling in water bearing ground within the framework of stress-pore pressure coupled analysis. Fundamental interaction mechanism of ground and groundwater lowering was first examined and a number of influencing factors on the results of coupled FE analysis were identified. A parametric study was then conducted on the influencing factors such as soil-water characteristics, location of hydraulic boundary conditions, the way of modeling drainage flow, among others. The results indicate that the soil-water characteristics plays the most important role in the tunneling-induced settlement characteristics. Based on the results, modeling guidelines were suggested for stress-pore prssure coupled finite element modeling of NATM tunneling.

• Geomechanics and Engineering
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• 제6권4호
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• pp.377-389
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• 2014

The vacuum consolidation method which was proposed by Kjellman in 1952 has been studied extensively and used successfully since early 1980 throughout the world, especially in East and Southeast Asia. Despite the increased successful use, different opinions still exist, especially in connection to distribution of vacuum with depth and time in vertical drains and in soil during preloading of soft ground. Porewater pressure measurements from actual cases of field vacuum and vacuum-fill preloading as well as laboratory studies have been examined. It is concluded that (a) a vacuum magnitude equal to that in the drainage blanket remains constant with depth and time within the vertical drains, (b) as expected, vacuum does not develop at the same rate within the soil at different depths; however, under ideal conditions vacuum is expected to become constant with depth in soil after the end of primary consolidation, and (c) there exists a possibility of internal leakage in vacuum intensity at some sublayers of a soft clay and silt deposit. A case history of vacuum loading with sufficient subsurface information is analyzed using the ILLICON procedure.

• 펄프종이기술
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• 제47권3호
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• pp.24-33
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• 2015

Linerboards containing wood flours were developed to increase solid contents in wet pressing process. Presence of wood flours in recycled fibers allowed passage of pressurized water at high wet pressing pressure, and increased solid contents while keeping the bulk of the board. The amount of wood flour addition should be controlled based on the intensity of the wet pressing pressure and the properties of the wood flours. Addition of cationic starch to the wood flour containing OCC furnish showed synergic increase of solid content and strength properties. Shapes of the wood flours such as spherical and rod type added to OCC furnish affected largely their solid content, drainage, and board physical properties.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.687-694
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• 2002

This paper presents the results of 3-D analysis on steady state flow in the region where the leakage in a cable tunnel is occurred due to high excess ground water pressure. In numerical modeling, a relief well is selected as a method of reduction in water pressure at the surrounding region of the cable tunnel. The distribution of ground water level after dewatering by relief wells is analyzed, Results show that the amount of dewatering level in the layer of hard rock is about 4.2∼8.6m, and that in the layer of fracture zone is about 5.8∼8.2m. The predicted settlement at the cable tunnel due to the increase of effective stress by dewatering is 0.3mm.

• Geomechanics and Engineering
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• 제28권4호
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• pp.405-419
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• 2022

Cavity expansion and contraction solutions for cylindrical and spherical cavities in unsaturated residual soils are presented in this paper. Varying soil state in the plastic zone is accounted by a numerical approach, wherein an element-by-element discretization of the plastic zone of both expanding and contracting cavities is carried out. Unlike existing methods utilizing self-similarity technique, the solution procedure enables the prediction of entire soil-state at any stage of expansion and subsequent contraction. It is also applicable for both cavity creation and expansion problems. The approach adopts constant contribution of suction to effective stress (constant X^s drainage condition) for analysis. The analysis procedure is validated by interpreting the previously reported pressuremeter test results in lateritic residual soil. The typical cavity expansion and contraction characteristics of unsaturated Indian lateritic soil were then examined using this solution procedure. The effect of initial soil-state on cavity limit pressure, plastic radius, reverse yield pressure, and reverse plastic radius are also presented.

• 한국농공학회논문집
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• 제59권4호
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• pp.43-52
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• 2017

This study analyzed pore water pressure, earth pressure and settlement through laboratory model tests in order to suggest the effective remodeling method in the case of reinforcing the upstream and downstream slope of deteriorated reservoirs that has no cores and filters or is not functional. The method of remodeling the upstream slope using dredge soil is first prevent seepage by installing the core, and the leakage water can be rapidly discharged through a filter installed on the downstream slope. Therefore, it is considered a highly efficient method of remodeling that reduces piping phenomena and increasing the storage capacity of the reservoir. The variation of earth pressure without the core and filter was greater than with it, while the change largely showed in the upstream slope, the downstream slope did not show any significant changes. The remodeling method of the downstream slope with the core appeared differently pore water pressure depending on the presence of the vertical and horizontal filters. In the upstream slope, the pore water pressure rises sharply, the base and middle gradually increased, and the downstream slope appeared small. The pore water pressure of embankment with a vertical and horizontal filter will be smaller than without it. The remodeling of deteriorated reservoir that does not have the function of the filter, the vertical filter must be installed in a position that is higher than the expected seepage line by removing portions of the downstream slopes. Since the horizontal filter is an important structure that provides stable drainage during an earthquake or concentrated leak, it is necessary to examine any change in the seepage characteristics depending on the filter intervals via three-dimensional finite element analysis, and it should be connected to the tow-drain to reduce the possibility of the collapse of the reservoir.

• 한국건축시공학회지
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• 제9권4호
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• pp.119-129
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• 2009

최근의 건축활동은 초고층화 대형화 복잡화 되고 있으며 도심지내에 근접 시공되어 짐에 따라 건축물의 지상층 높이증가와 더불어 지가의 앙등, 토지이용의 극대화로 지하구조물의 중요성이 증가되고 있으며 지하층의 면적 및 층수가 증가되어 가는 추세이다. 이에 따라 지하굴착심도가 깊어지고 있으며 토지 이용의 효율극대화 측면에서 우리나라의 경우 해안매립지등 매립지반에서의 건축활동이 급증하는 추세로 연약지반에 대한 대책과 아울러 지하수위에 대한 영향을 신중하게 검토해야할 필요성이 증대되고 있는 실정이다. 일반적으로 지하굴착 후 시공되는 건축물은 지층의성상과 토질, 수압 등에 대한 고려로 건물의 최하층 바닥슬라브 하부에 위치하게 되는 지하수위와의 수두압차에 의한 정수학적 압력(Hydrostatic Pressure), 즉 부력(Uplift Water Pressure)이 건물저면에 작용하게 되므로, 이러한 부력(浮力)합리적으로 대처할 수 있는 설계 및 시공법의 개발과 이를 적용하기 위한 노력은 지하층공사에 있어서 안전, 공기, 비용, 건축의질 측면에서 필수적이라고 할 수 있다. 그러나 이제까지의 지하층 공사는 부력 처리방법 등에 대한 연구가 미흡하며 기존의 공법 중 대상 프로젝트의 합리적인 수행을 위한 설계초기단계에서의 지반에 대한 사전조사와 면밀한 분석이 이루어지지 않고, 경험에 의존하는 경향이 크다. 본 연구는 상기와 같은 문제점을 바탕으로 O O 건설현장 실 사례를 중심으로 현장은 한강에 인접한 지리적 요인에 의해 지하수위가 한강의 수위와 연계되어 있는바 최초 계획되었던 Rock anchor System 대신 Drain mat System을 적용하여 유입되는 지하수를 유도, 배수함으로써 지하수위에 따른 상향수압을 통제할 수 있는 최적공법 선정을 통해 직접공사비 406,702,000원 및 Life Cycle Cost 차원에서 검토한 결과 건물수명 50년 기준 절감액 운용수익률 년 4% 절감의 효과로 이는 건설초기단계에서의 과다설계에 따른 투입 공사비의 과다책정, 공기의 증가 등에 따른 채산성 문제를 합리적으로 제어하여 건설공사의 원가절감을 위한 성공사례로 평가되고 있다.

• 한국지반신소재학회논문집
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• 제11권1호
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• pp.47-56
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• 2012

PBD의 통수능력은 지반조건 빛 두께에 비례하여 영향을 크게 받는 성질이 있으며, 배수재 타입 시 시용되는 맨드럴, 타입기기 및 방식에 의한 주변지반의 교란영향으로 배수성능이 저하되는 문제점 등이 있다. 또한, 여러 기지 조건에 따라 통수능의 편차가 크게 나타나며 원지반 조건에 따라 배수재의 통수능 저하, 간극수압소산의 시간지연 등의 분석이 미흡하다. 따리서 본 연구에서는 원지반 조건을 고려한 연직배수재의 복합 통수능 시험을 실시하여 지반개량 및 통수능 평가를 하였다. ${\phi}\;38{\times}70cm$ 크기의 원통형 실린더에 배수재를 고정한 후 교반한 시료를 투기하고 원지반 조건 CL, ML, SM과 준설토 CL을 매립한 후 가입장치를 사용하여 30, 70, 120 kpa의 하중을 가해 단계별로 복합통수능 실험을 수행하였다. 시험결과, 통수능의 크기는 원지반 조건이 SM>ML>CL>CL(준설토)인 순으로, 세립분 함량이 적을수록 통수량은 크게 나타났다.