• 한국조경학회지
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• 제28권2호
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• pp.61-70
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• 2000

The purpose of this study is to identify the proper species of turf and the ground structure for the turf sports grounds. Analysis items are particle distribution of sand and gravel, saturated hydraulic conductivity, soil hardness, and turf growth. Results of this study are as follows. 1)The particle distribution of sand used in the multi-layer rootzone is within the upper limit of the standard level. The diameter of mid-size grain({TEX}$D_{50}${/TEX})was 0.62mm and the value of uniformity ({TEX}$D_{90}${/TEX}/{TEX}$D_{10}${/TEX}) was 3.93. The particle size distribution of sand used in the single-layer rootzone was beyond the standard level as {TEX}$D_{50}${/TEX})=0.86 and {TEX}$D_{90}${/TEX}/{TEX}$D_{10}${/TEX}=8.86. 2) Saturated hydraulic conductivity of the sand was higher in the multi-layer rootzone than in the single-layer rootzone while bulk density was vice versa. 3) Surface hardness was high on Kentucky bluegrass+perennial ryegrass compared to zoysiagrass probably caused by root density. 4) Visual covering and visual rating were highly evaluated on zoysiagrass within summer while better evaluated on Kentucky bluegrass+perennial ryegrass throughout fall to spring. 5) Visual color was better evaluated on Kentucky bluegrass+perennial ryegrass than on zoysiagrass throughout the year. These studies are demanded urgently according to increase in interest in the ground and turf species of the turf sports ground because of World Cup 2002.

• 지구물리
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• 제6권2호
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• pp.49-56
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• 2003

Under the attack of storm waves, there are many destructions of coastal structures in the forms of sinking and sliding. There types of destructions will be in close relation to the dynamic behavior of sand bed around the structures. Form this point of view, in this pear, we investigate the characteristics of the pore water pressure and effective stresses in the highly saturated sand bed under oscillating water pressure theoretically. The results indicate that the oscillating water pressure induce the notable drop of strength of and bed around the structure under certain condition.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.27-33
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• 2011

Infiltration plays an important role in the urban water cycle. Infiltration has a potential to contribute to groundwater recharge in addition to runoff reduction. However, infiltration in urban areas has been considered only as a means of runoff reduction. Conventional design methods for infiltration facilities assume soils to be fully-saturated for the sake of simplicity. The amount of groundwater recharge can not be estimated properly with this scheme. Hence, the characteristics of the unsaturated soil condition need to be considered. The finite element model using SEEP/W to estimate infiltration under the unsaturated condition is presented. Infiltration tests for Joomonjin sand are performed and the infiltration behavior of Joomoonjin sand under the unsaturated condition is measured experimentally to verify the validity of the finite element model. The results from comparing infiltrated volume between the saturated and the unsaturated conditions under the same soil and rainfall conditions show that the infiltrated volume in the unsaturated condition is two times bigger than that in the saturated condition.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.743-750
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• 2002

Unsaturated soil has a possibility to induce a negative pore water pressure. Until now, saturated soil is mainly focused on the research of soil mechanics. Recently, soil mechanics is researched on two major parts such as saturated and unsaturated soil mechanics. Negative pore water pressure has a non-linear relationship with the water content changes. Soil-water characteristic curves of soil in Korea are not determined. There is no proper characteristic value such as air-entry value and residual water content. In this study, the characteristic curves of reclaimed soil, sand, and weathered granite soil were determined by laboratory tests. Air-entry value and residual water content were determined by fitting methods. Soil-water characteristic curves were estimated based on the particle-size distribution and compared with the laboratory test results. The results of soil-water characteristic curves estimation indicated that Fredlund and Wilson's model is excellent for sand and weathered granite soil. Arya and Paris's model is excellent for reclaimed soil.

• 한국지반공학회지:지반
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• 제14권3호
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• pp.47-62
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• 1998

본 연구에서 제안한 교란상태 개념 (disturbed state concept, DSC)은 변형중인 재료는 상대적으로 손상되지 않은 상태(relative intact state: Rl)와 완전히 파괴된 상태(fully adjusted state. FA)가 혼합되어 있다는 기본가정에 기초를 두고 있다. 여기에서 사용된 두 가지 상태, 즉 Rl상태와 FA상태는 재료의 파괴정도를 정의하는 기준이 된다. 이와 같은 개념을 바탕으로 DSC는 반복 하중하에 있는 포화사질토의 거동특성에 대한'통합된 구성방정식을 제공한다. 포화사질토에 대한 본 모델의 계수들은 실삼축시첩(truly triaxial test)의 결과를 통해 산정된다. 또한 실내실험을 통하여 얻은 결과를 이용하여 본 모델에 대한 검증을 수행하였다. DSC모델을 이용한 역해석 해석대상 시험결과는 전반적으로 일치되는 경향을 보이고있다. 본 연구의 결과를 토대로, DSC 모델은 동하중하의 구화 사질토의 거동특성을 규명할 수 있다고 사료된다.

• 대한지하수환경학회지
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• 제7권2호
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• pp.59-65
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• 2000

변동수압에 의한 포화 사질층의 연직 간극수압 분포를 이론 및 실험적으로 연구하였다. 실험에 의해 모래표면에 작용하는 수압은 모래층으로 전달되며 진폭이 감쇠하고 상이 지연되며, 유효응력이 0이 되는 액상화 현상이 특별조건에서 발생한다. 이러한 실험결과는 탄성 대수층에 대한 지하수문제와 같은 이론으로 잘 설명된다. 해석에 의한 액상화의 주요 특징은 다음과 같다: 1)액상화 심도는 진폭 및 변동수압의 주파수 증가에 따라 증가한다. 2)수량(水量)의 증가와 모래층 내의 공기가 많아짐에 따라 액상화 심도가 증가한다. 특히, 공기의 적은 양도 액상화에 크게 영향을 미친다. 3) 압축율이 증가함에 따라 액상화 심도는 감소한다. 4)투수 계수값이 어느 특정값 이상이 되면 투수계수 값이 증가함에 따라 액상화 심도는 감소한다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.341-345
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• 2004

An attempt has been made in this study to evaluate an applicability of Relative Effective Porosity Model (REPM) as a method for estimating saturated hydraulic conductivity (K$_{s}$) for homogeneous coarse, medium, and fine sands. The saturated hydraulic conductivities obtained from REPM are converted into average linear velocities using Darcy's Law and compared with the results from experimental tracer tests for homogeneous coarse, medium, and fine sand layer. Two types of tracer tests analyses, analytical solution using CXTFIT and moment methods, are performed to obtain reasonable linear velocity range for each layer. For the coarse and medium sands, the converted average linear velocity from REPM is in the velocity range obtained from tracer tests. However, small difference between the results from REPM and tracer tests is found for the fine sands. These results show that REPM gives reasonable estimates of saturated hydraulic conductivity.y.

• 한국토양비료학회지
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• 제18권4호
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• pp.352-358
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• 1985

1~0.5mm모래로 충전(充塡)한 sand column을 통해서 Zeolite가 수직(垂直) 유실(流失)과 수리전도도의 변화(變化)에 미치는 양이온의 영향(影響)을 조사(調査)한 결과(結果)는 다음과 같다. 1. Zeolite의 유실량(流失量)의 정도(程度)는 Na->K->$NH_4-$ Zeolite 순이었고 Mg-과 Ca-Zeolite는 유실(流失)되지 않았다. 2. Zeolite의 수직유실(垂直流失)은 주로 입자(粒子)들의 분산(分散)에 기인(基因)하였으며 투과용액(透過溶液)이 0.01N 농도(濃度)의 염용액(鹽溶液)에서 증류수(蒸溜水)로 바뀔때 분산(分散)이 가장 잘 일어났다. 3. 수리전도도(水理傳導度)의 변화(變化)가 심한 column 일수록 Zeolite 유실량(流失量)이 많았다.

• 한국지반공학회논문집
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• 제25권11호
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• pp.27-38
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• 2009

본 연구에서는 조밀한 포화 사질토 지반과 느슨한 포화 사질토 지반에 근입된 모형말뚝을 대상으로 다양한 말뚝휨 강성과 입력 가속도 진폭, 그리고 입력 가속도 진동수 조건에서 1g 진동대 실험을 수행하였다. 그 결과로, 조밀한 포화 사질토 지반조건에 대해, 각 실험 p-y 곡선 상 최대 지반 반력이 나타나는 꼭지점들을 연결하여 등가정적해석에 적용할 수 있는 동적 p-y 중추곡선을 쌍곡선 함수로 나타내었으며, 중추곡선을 쌍곡선 함수로 나타내는데 필요한 초기 기울기($k_{ini}$)와 극한 저항력($p_u$)을 결정하기 위한 경험식을 마찰각과 구속압의 함수로 제안하였다. 제안한 동적 p-y 중추곡선의 적용성을 기존 문헌에 발표된 원심모형실험 결과와 비교하여 검증하였으며, 실제 설계에 적용되고 있는 기존의 p-y 곡선들과도 비교, 분석하였다. 또한 느슨한 포화 사질토 지반조건에서, 진동 중 발생하는 과잉간극수압에 따라 지반 저항이 감소하는 정도를 나타내는 동적 지반 저항 감소 계수($S_F$)를 제안하였다.

• Geomechanics and Engineering
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• 제3권4호
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• pp.267-284
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• 2011

The aim of the paper is to study the hydro-mechanical behaviour of a tuff and calcareous sand mixture. A first experimental phase was carried out in order to find the optimal mixture. This showed that the material composed of 80% tuff and 20% calcareous sand provides the maximum mechanical strength. The second experimental phase concerns the study of the drying- wetting behaviour of the optimal mixture. Triaxial shear tests in saturated and unsaturated states at constant water content were carried out on samples initially compacted at the MPO. Experimental results let to deduce the parameters necessary for the prediction of the hydro-mechanical behaviour of pavement formulated from tuff and calcareous sand mixtures, related to moisture. This optimal mixture satisfies the regulation rules and hence constitutes a good local eco-material, abundantly available, for the conception of pavements.