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Lysimeters are always utilized to simulate the landfill environmental conditions due to their relatively low expense and the short duration of the research. However, lysimeters tend to be operated with various geometrical characteristics (e.g. height/width ratio and height) which can result in changes to the physical and thermodynamic characteristics, and affect the waste decomposition rates and leaching behavior. Considering these points, in this study, the lysimeter test was conducted using six lysimeters to evaluate the size effect on leachate generation and leaching behavior of construction and demolition waste residue (C&D waste). According to the lysimeter test results, increasing the width of the lysimeter can reduce the potential of side-edge-wall flow, and the filtration water can have a perfect flushing inside lysimeters with shorter lengths. Increasing the height merely results in an increase in upper loading, and results in waste with a denser micro-structure and with closer cohesion at the bottom of the lysimeters, which was not suitable for the leaching out of soluble constituents or heavy metals. The lysimeters with low height/width ratio can promote the leaching behavior and accelerate the dilution of landfill leacahte. In addition, the emission behaviors of some inorganic ions indicate microbial activity can have a significant effect on leaching behavior, which cannot be neglected when researching landfill waste. It is suggested that lysimeters with lower height and a lower H / W ratio are a better choice when investigating leaching behavior or microbial activity. These results contribute to establishing standardized feasible designs for laboratory-scale lysimeter tests.

土壌・地下水汚染対策工法の反応透過壁工法(反応性バリア)を対象として，その設計パラメータを平面2次元浸透流解析により評価した。その結果に基づき，汚染サイトの特性に応じた最適な反応透過壁構造を見出すことができる設計手法を提案した。汚染サイトを正常に浄化することのできる条件を満たし，なおかつ施工費用が最小になるという視点から最適な反応透過壁構造を議論した。, Performance of permeable reactive barriers for contaminated groundwater remediation was evaluated using FEM seepage analysis. The retention time and the capture zone were calculated on the funnel-and-gate systems (FGSs) having different geometries, in order to evaluate the effects of these geometries on the FGSs performance. Based on the calculated results, costs associated with the installation of funnel-and-gate systems satisfying a certain performance were obtained to estimate the cost-effective geometry. Finally, optimum design flow for FGS was proposed.

高密度非水溶性流体相(DNAPL)の地盤内の浸透特性は相対透水係数(κ), 飽和度(S), 間隙水圧(p)の関係で表すことが可能である。これら3個のパラメーターの関係はk-S-p rdationと呼ばれるもので, 水・空気2相流系, すなわち不飽和浸透における関係と同義である。本研究の目的は, 非混合性の液液2相流下におけるk-S-p relationを明確にしょうとするものである。地盤内における液液2相流の概念を明確にし, DNAPL, ならびに地盤特性がk-S-p relationに及ぼす影響を, 二次元有限要素コードMOFATを利用し解析的に求めた。解析は1次元カラムモデルと2次元土槽モデルを対象として行った。これらの解析結果は浄化手法やDNAPL浸透の行方を評価する上で有効となる基本的概念を示すものである。, Migration properties of dense non-aqueous phase liquids (DNAPLs) in the subsurface can be expressed as a water-NAPL two-phase system based on the permeability (k), saturation (S), and pressure (p), similar to an unsaturated water-air two-phase system. This relation is called "k-S-p relation". In this paper, first, the concept of the migration processes under the liquid-liquid immiscible two-phase flow condition is presented. Second, to estimate the influence of the fluid properties and subsurface conditions on the k-S-p relations, the analysis for these parameters is performed by using the finite element code MOFAT. Finally, two-dimensional tank analyses in homogenous and heterogeneous subsurface conditions are performed for evaluating the effect of the rate of groundwater flow. This numerical results indicate the fundamental behavior of DNAPL migration under the two-phase flow system in the aquifer.

管理型海面埋立処分場におけるケーソン式遮水護岸を対象として, 二次元移流分散解析により有害物質の移流拡散挙動を評価した。その結果に基づいて, 遮水工の性能照査を行い, および適正な護岸構造を提案した。特に遮水シートの損傷およびケーソン継ぎ手部からの漏出, 裏込め材料の透水性, 遮水シートの接地長が護岸の遮水性に与える影響を検討し, 適正な護岸構造形式を有害物質の遮蔽性能の点から議論した。, Performance of a caisson-type sea wall for the contaminant isolation of coastal disposal site was discussed in terms of released contaminant concentration and mass flux using the 2-D advection and dispersion analysis. The main concerns were I) the contaminant leakage through the defects in geomembrane and the joints of each caisson, ii) permeability of the backfill material, and iii) geometric install pattern of the impermeable sheet.

有害物質を含有する底泥を処分した処分地からの物質の移流拡散挙動を二次元移流分散解析プログラム「Dtransu-2D･EL」を用いて解析を実施し, 周辺環境に与えるインパクト評価を実施した。処分場の底部構造は海底粘土地盤であり, 側部は二重矢板による締切り工によって遮蔽されている海面埋立処分場を想定した。鋼矢板の透水係数と締切り矢板中詰砂の透水性をパラメーターとして解析し, 濃度, フラックス, 全水頭によって, それぞれのの影響を評価した。透水性地盤改良の施工では, 処分場のサービスライフを考慮することで改良幅に最適解が存在することが確認された。その最適幅は改良地盤の透水係数の設計値によって変化するものであり, 透水係数が設計において最も大切なファクターとなる。本研究は適切な処分場の設計方法に対する一提案を行うものである。, Transport of toxic chemicals from a sludge disposal site is evaluated using two-dimensional advection-dispersion program "Dtransu-2D･EL." The site analyzed is a coastal disposal site using natural clay layer as bottom liner and double steel sheet piles having a distance of 15 m for preventing the lateral movement of chemicals. Hydraulic conductivity values of the sheet piles and filling material between piles were parametrically changed to discuss the effect on ground improvement. The analyzed results were discussed from the distribution of chemical concentration around the area, mass flux across the outer sheet piles, and service life of the disposal site. The main results are (1) hydraulic conductivity of filling material has a significant effect on reducing the chemical transport, (2) chemical transport is decreased with the increase in the width of the ground improvement area between the sheet piles if the area is smaller than 7 m. Based on this analytical study, a method of appropriate design of disposal site has been suggested.

Performance of permeable reactive barriers for contaminated groundwater remediation was evaluated using FEM seepage analysis. The retention time and the capture zone were calculated on the funnel-and-gate systems (FGSs) having different geometries, in order to evaluate the effects of these geometries on the FGSs performance. Based on the calculated results, costs associated with the installation of funnel-and-gate systems satisfying a certain performance were obtained to estimate the cost-effective geometry. Finally, optimum design flow for FGS was proposed.

Performance of a caisson-type sea wall for the contaminant isolation of coastal disposal site was discussed in terms of released contaminant concentration and mass flux using the 2-D advection and dispersion analysis. The main concerns were I) the contaminant leakage through the defects in geomembrane and the joints of each caisson, ii) permeability of the backfill material, and iii) geometric install pattern of the impermeable sheet.

Migration properties of dense non-aqueous phase liquids (DNAPLs) in the subsurface can be expressed as a water-NAPL two-phase system based on the permeability (k), saturation (S), and pressure (p), similar to an unsaturated water-air two-phase system. This relation is called "k-S-p relation". In this paper, first, the concept of the migration processes under the liquid-liquid immiscible two-phase flow condition is presented. Second, to estimate the influence of the fluid properties and subsurface conditions on the k-S-p relations, the analysis for these parameters is performed by using the finite element code MOFAT. Finally, two-dimensional tank analyses in homogenous and heterogeneous subsurface conditions are performed for evaluating the effect of the rate of groundwater flow. This numerical results indicate the fundamental behavior of DNAPL migration under the two-phase flow system in the aquifer.