• 한국지반공학회논문집
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• 제18권4호
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• pp.147-157
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• 2002

본 연구에서는 방사방향의 배수조건을 갖는 점성토의 압밀특성을 짧은 시간에 정확하게 평가할 수 있는 방사배수 일정변형률 압밀시험을 위한 시험기와 해석이론을 개발하였다. 개발된 시험기 및 해석이론에 대한 적용성을 검토하기 위하여 성형시료 및 불교란 시료에 대하여 방사배수 일정변형률 압밀시험과 단계하중 압밀시험을 실시하였다. 압밀곡선으로부터 평가되는 압밀정수 및 압밀계수에 대한 비교, 분석을 통하여 제안된 시험기 및 이론의 신뢰성과 적용성을 평가하였고, 방사배수 시험과 더불어 수행된 연직배수 일정변형률 압밀시험과 단계하중 압밀시험을 통하여 배수방향에 따른 영향과 시험기 및 해석이론의 적용성을 분석하였다. 또한, 일정변형률 압밀시험시 발생하는 과잉간극수압에 대한 분석을 통하여 간극수압의 발생 양상 및 실험결과에 미치는 영향을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1400-1407
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• 2005

There are a number of approaches to in situ remediation that are used at contaminated sites for removing contaminants from the contaminated zone without excavating the soil. These include soil flushing, dual phase extraction, and soil vapor extraction. Of these techniques, soil flushing is the focus of the investigation in this paper. The concept of using prefabricated vertical drains(PVDs) for remediation of contaminated sites with fine-grained soils is examined. The PVD system is used to shorten the drainage path or the groundwater flow and promote subsurface liquid movement expediting the soil flushing process. The use of PVDs in the current state of practice has been limited to soil improvement. The use of PVDs under vacuum conditions is investigated using sample soil consisting of silty sand.

• 한국수자원학회논문집
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• 제50권2호
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• pp.129-138
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• 2017

대심도 저류 및 배수터널은 기 개발된 도시의 부족한 배수관망 능력을 보강하기 위하여 지하에 설치하는 대규모 도시홍수 배제 시설물로 원활한 홍수 유입을 위해 적정한 규모의 수직유입구가 요구되어진다. 접선형 수직유입구 설계 시 유입구의 능력을 평가하는 중요인자로 Yu and Lee(2009)가 지배유량개념을 소개하였는데, 본 연구에서는 서울시에 설치하고자 하는 신월빗물저류배수시설의 수직유입구 3개소를 대상으로 수리모형실험을 실시하고 제안된 지배유량 개념의 적정성을 평가하였다. 지배유량 이론식($Q_{cp}$)을 이용하여 실제 측정된 지배유량($Q_{cm}$)과 비교 분석하였는데, 그 결과 이론식 대비 66~69%로 이론식이 지배유량을 과대 산정하는 것으로 평가되었다. 지배유량 이론식의 과대산정 원인을 분석하기 위하여 Yu and Lee (2009)가 사용한 자료들과 본 연구에서 측정된 자료들을 활용하여 지배유량비($Q_{cm}/Q_{cp}$)를 3가지 영역으로 분류하고 각 인자에 대한 민감도 분석을 실시하였다. Yu and Lee (2009)가 제안한 지배유량식은 접선형 수직유입구 설계인자인 B, z, ${\beta}$, e/B에 대한 영향만 고려하였으나 ${\theta}$, L과 연계된 변수들로 복합적으로 고려하는 식의 개선이 필요한 것으로 판단된다.

• 한국지반공학회논문집
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• 제21권2호
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• pp.67-84
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• 2005

본 연구는 포화된 연약 점성토에 대한 보강효과를 분석하기 위하여 롤러 다짐장비를 사용하여 수행하였다. 시료는 12시간 수침으로 포화 상태를 만들었으며, 철재 롤러로 평면변형을 상태에서 5cm 층 두께로 4층의 다짐을 실시하였다. 보강효과를 분석하기 위하여 무보강 조건 및 부직포와 직포로 구성된 복합보강재를 사용한 보강조건으로 다짐 공시체를 제작하였다. 복합보강재의 배수효과와 인장 보강효과로 고함수비 점성토의 지지력을 증가시켜, 보강토에 대하여 큰 다짐하중을 가할 수 있게 되어 보다 큰 밀도를 효과적으로 얻을 수 있다. 또한 다짐 작업시 보강재에 의해 연직재하 하중에 대한 전단저항 반력의 감소에 의해 다짐효율을 증가시킨다. 공시체 저면에서의 최대 연직응력은 다짐두께가증가 할수록 감소하게 된다. 한편 보강재는 롤러의 연직하부의 지반강성을 증가시켜 응력집중현상이 발생한다. 이로인하여 공시체 저면에서 보다 높은 연직응력 수준을 유지하며 보다 효과적인 다짐 특성을 제공하게 된다. 시험결과로부터 연약점성토의 효과적인 다짐을 위해서는 보강재가 필수적으로 요구된다고 할 수 있다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
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• pp.93-112
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• 2000

The permeability of converter slag, replacing material of sand mat on improving soft clay foundation, was evaluated in the laboratory. The effects of grain size, flow water time and aging were investigated using sea and fresh water. Converter slag being submerged with fresh water, the coefficients of permeability in A and B samples less than 10mm grain sizes were measured as 6.52${\times}$10$\^$-2/cm/sec and 5.99${\times}$10$\^$-1/cm/sec, while changed as 1.88${\times}$10$\^$-2/cm/sec, 3.86${\times}$10$\^$-1/cm/sec under sea water condition. Also, the condition of turbulent flow may exit and was experimentally identified from the relationship between hydraulic gradient and seepage velocity. After 180 days on using sea water, the coefficients of permeability of sample A and B samples decreased ten times smaller than those initial values. And after that time continually decreased as for till 360 days. The reduction of permeability coefficient was considered to influence filled with voids in high-calcium quicklime(CaO). However, in-situ coefficient of permeability was practically satisfactory.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
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• pp.12-31
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• 2000

The permeability of converter slag, replacing material of sand mat on improving soft clay foundation, was evaluated in the laboratory. The effects of grain size, flow water time and aging were investigated using sea and fresh water. Converter slag being submerged with fresh water, the coefficients of permeability in A and B samples less than 10mm grain sizes were measured as 6.52${\times}$10$\^$-2/cm/sec and 5,99${\times}$10$\^$-1/cm/sec, while changed as 1,88${\times}$10$\^$-2/cm/sec, 3.86${\times}$10$\^$-1/cm/sec under sea water condition. Also, the condition of turbulent flow may exit and was experimentally identified from the relationship between hydraulic gradient and seepage velocity. After 180 days on using sea water, the coefficients of permeability of sample A and B samples decreased ten times smaller than those initial values. And after that time continually decreased as for till 360 days. The reduction of permeability coefficient was considered to influence filled with voids in high-calcium quicklime(CaO). However, in-situ coefficient of permeability was practically satisfactory.

• 한국농공학회지
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• 제30권1호
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• pp.38-49
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• 1988

This paper presented as follows results of laboratory model tests with various shaped footings on soil bed reinforced with the strips on the base of behaviour of soil structure according to the loads and triaxial test results reinforced with geotextiles. Their parameters studied were the effects on the bearing capacity of a footing of the first layer of reinforcement, horizontal and vertical spacing of layers, number of layers, tensile strength of reinforcement and iclination load to the vertical 1.Depending on the strip arrangement, ultimate bearing capacity values could be more improved than urreinforced soil and the failure of soil was that the soil structure was transfered from the macrospace to microspase and its arrangement, from edge to edge to face to face. 2.The reinforcement was produced the reinforcing effects due to controlling the value of factor of one and permeable reinforcement was never a barrier of drainage condition. 3.Strength ratio was decreased as a linear shape according to increment of saturation degree of soil used even though at the lower strength ratio, the value of M-factor was rot influenced on the strength ratio but impermeable reinforcement decreased the strength of bearing capacity. 4.Ultimate bearing capacity under the plane-strain condition was appeared a little larger than triaxial or the other theoretical formulars and the circular footing more effective. 5.The maximum reinforcing effects were obtained at U I B=o.5, B / B=3 and N=3, when over that limit only acting as a anchor, and same strength of fabric appeared larger reinforcing effects compared to the thinner one. 6.As the LDR increased, more and more BCR occurred and there was appeared a block action below Z / B=O.5, but over the value, decrement of BCR was shown linear relation, and no effects above one. 7.The coefficient of the inclination was shown of minimum at the three layers of fabrics, but the value of H / B related to the ultimate load was decreased as increment of inclination degree, even though over the value of 4.5 there wasn't expected to the reinforcing effects As a consequence of the effects on load inclination, the degree of inclination of 15 per cent was decreased the bearing capacity of 70 per cent but irnproved the effects of 45 per cent through the insertion of geotextile.

• 한국지반환경공학회 논문집
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• 제12권10호
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• pp.39-49
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• 2011

최근 연약지반에서는 공사기간 중에 압밀에 의한 침하량이 빠르게 일어날 수 있도록 압밀시간을 단축시키는 압밀촉진공법 중 하나인 PBD공법이 적용되고 있다. 이는 시공의 용이성과 경제성을 지닌 압밀촉진 공법 중 하나이다. PBD는 통수능력이 연약층의 두께에 비례하여 영향을 크게 받는 성질이 있으며, 배수재 타설 방법과 관련하여 배수재 타입 시 사용되는 맨드럴, 타입기기 및 방식에 의한 주변지반의 교란영향으로 배수성능이 저하되는 등 문제점이 있다. 또한 지반조건, 시공조건, 토질특성에 따라 통수능의 편차가 크게 나타나며 PBD타설 후 강우나 성토재료 수급의 불안정 등 기타 현장여건에 따라 성토 재하중을 바로 실시하지 못해 수개월 동안 방치에 따른 배수재 통수능의 문제점 및 분석이 미흡한 실정이다. 따라서 본 연구에서는 방치기간에 따른 PBD 통수능의 영향인자를 분석하기 위한 복합 통수능 시험을 실시하여 지반개량 및 통수능 평가를 하였다. 원통형 실린더에 배수재를 고정한 후에 교반한 시료를 투기한 후 0day, 30day, 60day, 90day 방치시킨 후에 가압장치를 사용하여 30, 70, 120kPa의 하중을 가해 실험을 수행하였다. 실험결과, PBD 타설 후 방치기간이 길어질수록 통수능이 감소하는 것을 확인할 수 있었다. 이는 장기간 방치에 따른 PBD필터의 흡습에 기인된 크리프 변형으로 통수단면의 감소가 원인이라고 판단할 수 있다.

• Geomechanics and Engineering
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• 제8권1호
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• pp.81-95
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• 2015

The permeability behavior of Ariake clays has been investigated by constant rate of strain (CRS) consolidation tests with vertical or radial drainage. Three types of Ariake clays, namely undisturbed Ariake clay samples from the Saga plain, Japan (aged Ariake clay), clay deposit in shallow seabed of the Ariake Sea (young Ariake clay) and reconstituted Ariake clay samples using the soil sampled from the Saga plain, were tested. The test results indicate that the deduced permeability in the horizontal direction ($k_h$) is generally larger than that in the vertical direction ($k_v$). Under odometer condition, the permeability ratio ($k_h/k_v$) increases with the vertical strain. It is also found that the development of the permeability anisotropy is influenced by the inter-particle bonds and clay content of the sample. The aged Ariake clay has stronger initial inter-particle bonds than the young and reconstituted Ariake clays, resulting in slower increase of $k_h/k_v$ with the vertical strain. The young Ariake clay has higher clay content than the reconstituted Ariake clay, resulting in higher values of $k_h/k_v$. The microstructure of the samples before and after the consolidation test has been examined qualitatively by scanning electron microscopy (SEM) image and semi-quantitatively by mercury intrusion porosimetry (MIP) tests. The SEM images indicate that there are more cut edges of platy clay particles on a vertical plane (with respect to the deposition direction) and there are more faces of platy clay particles on a horizontal plane. This tendency increases with the increase of one-dimensional (1D) deformation. MIP test results show that using a sample with a larger vertical surface area has a larger cumulative intruded pore volume, i.e., mercury can be intruded into the sample more easily from the horizontal direction (vertical plane) under the same pressure. Therefore, the permeability anisotropy of Ariake clays is the result of the anisotropic microstructure of the clay samples.

• 상하수도학회지
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• 제9권4호
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• pp.73-86
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• 1995

The propriety of the numerical model application was examined on Paldang resevoir and its inflow tributaries located in the center of the Korean peninsula and the long term water quality forecast of the oxygen profile was carried out in this syduy. The input data of the model was the capacity of the reservoir, catchment area, percolation, diffusion rate, vertical mixing rate, dissolution rate from the bottom of the reservoir, outflow of the resevoir, water quality measurement and meteorology data of the drainage basin, and the output result was the annual estimation value of the dissolved oxygen concentration and the biochemical oxygen demand. The modeling method is based on the measured or calculated boundary condition dividing the water area into several blocks from the macorscopic aspect and considering the mass balance in these blocks. As the result of the water quality forecast, it was expected that the water quality in Northern Han River and Paldang reservoir would maintain the recent level, but that the water quality in the Southern Han River and its inflow tributary would worsen below the grade 4 of the life environmental standard from around 2000 owing to the decrease of DO concentration and the increase of BOD concentration.