• Title/Summary/Keyword: geo-material

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Numerical Formulation for Flow Analysis of Dredged Soil (준설토 유동해석을 위한 유한요소 수식화)

  • Shin, Hosung
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.3
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    • pp.41-48
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    • 2014
  • Experimental study of sedimentation and self-weight consolidation has been primary research area in dredged soil. However, good quality of the dredged soil and minimum water pollution caused by the pumping of reclaimed soil require intensive study of the flow characteristics of dredged material due to dumping. In this study, continuity and the equilibrium equations for mass flow assuming single phase was derived to simulate mass flow in dredged containment area. To optimize computation and modeling time for three dimensional geometry and boundary conditions, depth integration is applied to governing equations to consider three dimensional topography of the site. Petrov-Galerkin formulation is applied in spatial discretization of governing equations. Generalized trapezoidal rule is used for time integration, and Newton iteration process approximated the solution. DG and CDG technique were used for weighting matrix in discontinuous test function in dredged flow analysis, and numerical stability was evaluated by performed a square slump simulation. A comparative analysis for numerical methods showed that DG method applied to SU / PG formulation gives minimal pseudo oscillation and reliable numerical results.

An Experimental Study on the Behavior of Capping Material by Sea Waves (파랑에 의한 피복재의 거동에 관한 실험적 연구)

  • Kong, Jinyoung;Kim, Youngtak;Kang, Jaemo;Lee, Jangguen
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.7
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    • pp.51-58
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    • 2014
  • In-situ capping is a method to stabilize contaminated sediments by isolation. Few researches on the in-situ capping have been performed, although the engineering approach is still required to prevent the release of contaminants. In this study, hydraulic model test were conducted by using a wave generator to observe the change of cap thickness which is important factor in design of capping. Sands with particle size between 0.075 to 2 mm as capping materials were used to observe the change of capping thickness by waves. The experimental results show that the surface of capping materials is similar to wave form. The more wave height increases, the more erosion of capping materials increases.

Effects of Pile Diameter on the Lateral Behavior of Offshore Pile in the Southwestern Area of Korea (서남해안 해상풍력단지 말뚝의 직경에 따른 횡방향 거동)

  • Lee, In;Choi, Younggyun;Kim, Honglak;Kwon, Osoon;Youn, Heejung
    • Journal of the Korean GEO-environmental Society
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    • v.14 no.5
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    • pp.23-32
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    • 2013
  • This paper presents the effect of pile diameter on the lateral behavior of offshore pile for wind turbine. The material parameters of the soils were estimated through SPT on the Southwestern offshore area in Korea, where the first wind farm is planned. The FDM software, FLAC3D, and LPile were adopted to derive the load-displacement curve, p-y curve, and maximum bending moment at a specified displacement. It was found that the results from softwares significantly differ and the LPile could overestimate the allowable capacity. The maximum bending moment along the pile with 2m diameter could be as large as four times the bending moment with 1m diameter. Similar trend was observed for the allowable lateral capacity.

Optical Sensor Support Structure for Geo-stationary Satellite (정지궤도 위성의 광학 센서 지지 구조물)

  • Kim, Chang-Ho;Kim, Kyung-Won;Kim, Sun-Won;Lim, Jae-Hyuk;Hwang, Do-Soon
    • Journal of Satellite, Information and Communications
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    • v.5 no.2
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    • pp.8-13
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    • 2010
  • Satellite structure should be designed to accommodate and support safely the payload and equipments necessary for its own missions and to secure satellite and payloads from severe launch environments. The launch environments imposed on satellites are quasi-static accelerations, aerodynamic loads, acoustic loads and shock loads. Especially when optical payload is accommodated, satellite structure usually adopts the optical bench consisting of composite material not only to support and secure but also to guarantee good pointing stability against extreme thermal environments. This paper deals with optical bench and support structure which shall be designed to minimize the loads transferred to optical payloads from satellite.

Bearing Capacity Characteristics of Stone Column by Numerical Analysis (수치해석에 의한 쇄석기둥의 지지력 특성)

  • Chun, Byung-Sik;Kim, Baek-Young
    • Journal of the Korean GEO-environmental Society
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    • v.5 no.1
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    • pp.75-84
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    • 2004
  • Stone column is one of the soft ground improvement method, which can enhance ground conditions such as the settlement reduction and the increasement of bearing capacity with applying the crushed stone instead of sand. In recent, general construction material, sand is in short of supply. Therefore, the bearing capacity improvement by the stone column is considered as the alternative method needed in many cases so the bearing capacity estimation is considered as important point. Nevertheless, adequate estimation methods to predict bearing capacity of stone column considering stone column and improvement effect of ground is not yet prepared. For the analysis of above mentioned points, the behavior of stone column were simulated as numerically on various property cases of crushed stone and surrounded ground. Through the numerical analysis of simulation results, the formula for the bearing capacity estimation of stone column was suggested. This formula was verified by comparing the prediction result of in situ test.

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Influence of pH on Mn Concentration of Effluent from Sludge Thickener of Water Treatment Plant (정수장 슬러지 농축조 배출수의 망간 농도에 미치는 pH의 영향)

  • Kim, Younjung;Lee, Seungeun;Baek, Seungcheol;Kim, Taeheui
    • Journal of the Korean GEO-environmental Society
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    • v.16 no.5
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    • pp.27-33
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    • 2015
  • Manganese in sludge precipitated during water treatment might be soluble again in effluent from sludge thickener. If that happens, the manganese concentration of effluent from water treatment plant will exceed the limit for clean reservation. In this study the influence of pH on Mn concentration of effluent from sludge thickener of water treatment plant was investigated. When the pHs of sludge solutions increased with alkaline materials such as NaOH, KOH, CaO, $Ca(OH)_2$, $CaCO_3$, the Mn concentrations of sludge solutions decreased under the limit. The Mn concentration of effluent from sludge thickener could be controlled with waste limestones from beneficiation process at limestone mine as an alkaline material.

A Study on the Improvement Mechanical Properties of Geosynthetic Interface (토목섬유 접촉면의 역학적 특성 개선에 관한 연구)

  • Nam, Yong;Kim, Gwangho;Kwon, Jeonggeun;Im, Jongchul;Seo, Jeochan
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.3
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    • pp.23-32
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    • 2010
  • In this study, Generally sandbag was used to reinforce slope or restore levee by using the in-situ material. To increase shear strength of sandbag, the Velcro system was effective for geosynthetic interface and make up for the weakness of shear strength between sandbag to sandbag. In this study, shear properties of geosynthetic-geosynthetic and geosynthetic-soil were evaluated from large scale direct shear tests. The cohesion and the angle of internal friction of each interface was evaluated. And laboratory model tests were performed to compare strength of reinforcement with strength of none reinforcement. As a result of this study, the cohesion and the angle of internal friction of each interface was increased, especially the cohesion was increased more than the angle of internal friction. Also according to the result of model test, the bearing capacity was increased by 20%.

Reclamation of Closed Non-Sanitary Landfills by Sorting Transfer Control (선별이적처리를 통한 사용종료 비위생매립지 정비방안 연구)

  • Kim, Dongoh;Kim, Taekyoung;Kim, Mihwa;Kim, Moonil
    • Journal of the Korean GEO-environmental Society
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    • v.10 no.1
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    • pp.15-23
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    • 2009
  • The aim of this study was an evaluation of closed non-sanitary landfill's stabilization degree and a determination of its an optimal reclamation method. In order to evaluate the stabilization degree, physical compositions of landfill wastes in 21 closed non-sanitary landfills were analyzed. There were 4 major items such as cover soils, organics, combustibles and incombustibles. With respect to the results of physical compositions, it was determined that the waste in 9 sampling sites of closed non-sanitary landfills after 10years of the relief time was not fully stabilized. The closed non-sanitary landfills must be reclaimed as soon as possible. The main material in closed non-sanitary landfills was cover soils and the highest content was 89.96%. Otherwise, the contents in sanitary landfills was small and 9.89~11.12%. Therefore, it was evaluated that the recovered soil by sorting transfer treatment could be reused as on-site cover soils of the reclamating non-sanitary landfills and/or constructing materials.

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Anti-Corrosion Property of Geopolymer Evaluated by an Impressed Current Cathodic Protection Method, Exposed to Marine Environment (염해환경에서 외부전원법에 의한 지오폴리머 시험체 보강철근의 방식특성 평가)

  • Lee, Hae-Seung;Cho, Ggu-Hwan;Park, Dong-Cheon
    • Journal of the Korea Institute of Building Construction
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    • v.14 no.5
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    • pp.397-405
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    • 2014
  • There are many literatures reporting that the service life of re-bars in concrete structures is reduced in the oceanic environment due to chloride attack. To solve this problem, this study used geo-polymer as a mix material for concrete to increase its resistance to salt damage, and the external voltage method, one of the electric methods, is was applied to evaluate the likelihood of re-bars in the oceanic structure being exposed to the extreme salt environment. The items evaluated include the natural potential of re-bars and the corrosion rate. The results of the tests showed that in all of the salt environmental conditions (submerged zone, tidal zone, and crack), the tested materials were remarkably effective compared with ordinary concrete. The corrosion protective property was found not only in the evaluation of the natural potential but also in the evaluation of the corrosion rate, suggesting that the external voltage method can be used stably for geo-polymer RC structures in an extreme salt environment.

Reinforced Effect of Staple Fiber for Soil - Waste Stone Sludge (폐석분 혼합토의 단섬유 보강 효과)

  • Choi, Min-Kyu;Park, Beum-Sic;Kim, Young-Muk
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.8
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    • pp.45-55
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    • 2012
  • This study is about the application of waste stone sludge as fill material. Waste stone sludge, weathered granite soil, and the mixture of the former and the latter strengthened with staple fiber are experimentally analyzed for measuring strength property. When staple fiber was mixed with waste stone sludge, weathered granite soil, and the mixture, there was a nearly linear relationship between the amount of the staple fiber and the increasing ratio of unconfined compressive strength. The increasing ratio of unconfined compressive strength was the largest in weathered granite soil. The increasing ratio of unconfined compressive strength of the mixture was similar to that of waste stone sludge. In the case of the mixture of weathered granite soil and waste stone sludge, an internal friction angle tended to increases rely on increasement of staple fiber content, whereas the change of cohesion was small. An internal friction angle was increased by 21 percent when staple fiber content is 0.75 percent. Comparing with weathered granite soil or waste stone sludge, strength parameters of the mixture were increased relatively. Thus strengthening effect of staple fiber in the mixture is expected.