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It is important to understand the long-term migration of radionuclides when considering rock engineering projects such as the geological disposal of radioactive waste. The network of fractures and pores in a rock mass plays a major role in fluid migration as it provides a pathway for fluid flow. The geometry of a network can change due to fracture sealing by some fine-grained materials over long-term periods. Groundwater usually contains finegrained minerals such as clay minerals, and it is probable that the accumulation of such minerals occurs within a rock fracture upon groundwater flow, thereby decreasing the aperture of a fracture and the permeability. It is therefore essential to conduct permeability measurements using water that includes fine-grained minerals to understand the permeability characteristics of a rock; however, this has not been studied to date. In the present study, we use a macro-fractured granite sample to investigate the change of permeability that occurs under the flow of water that includes two different amounts of clay. Findings showed that clay accumulated in a fracture and that the permeability (hydraulic conductivity) of the granite sample decreased over time, which was greater in for the higher clay content. We concluded that the accumulation of clay minerals in the fracture decreased the permeability of the rock. Furthermore, we consider that the filling and closure of fractures in rock is possible under the flow of groundwater that includes clay minerals.

The purpose of this study is to understand the relationship between the amount of frozen / unfrozen water in a saturated fine-grained soil and its consolidation characteristics. In this study,we compared and examined the relationship between the frozen / unfrozen void ratio and the geotechnical engineering properties (compression index, coefficient of permeability and coefficient of volume change) of a fine-grained soil (Shirotsuchi clay). It was revealed that the newly proposed frozen void ratio was related to the geotechnical engineering properties, and the unfrozen void ratio has no relation to them. Therefore, it was considered that the free water represented by frozen void ratio governs the consolidation characteristics.

The purpose of this study is to assess the permeability of unfrozen part of the freezing earth wall. When the ground freezes, an ice lens is generated, and the ground is divided into frozen soil and unfrozen soil with this ice lens as the boundary. If the frozen earth wall is maintained for a long period of time, shrinkage cracks may occur due to dehydration consolidation of unfrozen soil, and groundwater can flow into the unfrozen soil generating water supply that bypasses the frozen earth wall. In this study, the coefficient of vertical permeabilities along the ice lens before, during, and after freeze-thaw were experimentally investigated. Using the hydraulic conductivity kp obtained in the standard consolidation test, the relational expression between the void ratio and the coefficient of permeability was obtained. As a result, the coefficient of permeability of the frozen-thawed soil was greater than that in the unfrozen state. In particular, the permeability after thawing was the greatest among them. The measured coefficient of permeability was much greater than the estimated coefficient of permeability from a consolidation test. Comparing the estimated coefficient of permeability with the measured value, it was 2 times greater in the unfrozen soil part during freezing and 100 times in the frozen-thawed soil. The reason why the measured coefficient of permeability was greater than the estimated value is, we suppose that the invisible shrinkage cracks generated in the freeze-thaw tests works as the water paths.

The purpose of this study is to evaluate the influence of freezing direction on the permeability of freeze-thawed soils. In this study, the permeability of both ice lens (IL) and IL orthogonal directions in the freeze-thawed soil were experimentally investigated. As a result, the permeability of IL direction was greater than IL orthogonal direction. Especially, the permeability of open-system freeze-thawed soils increased remarkably and it received not only the overburden pressure but also the influenced of both condition of pre-consolidation pressure and the number of freeze-thaw cycles. The permeability of closed-system freeze-thawed soils was lower than that of open-system. It was concluded that the permeability of freeze-thawed soil of IL direction is greater because of the remarkably greater void ratio in the colder temperature side of freezing.

The transient pulse method is suitable for measuring hydraulic constants of low-permeability rocks in the laboratory. This method is established and reliable; however, there is room for improvement. In this study, we examined analytical solutions of the transient pulse method and introduced a versatile technique of precise test data analysis with sensitivity analysis and experimental error estimation that is based on the nonlinear least-squares method and is applicable to other permeability tests. We also carried out highly precise transient pulse permeability tests in the laboratory and obtained highly precise experimental data. Based on the results, we validated our proposed data analysis technique based on nonlinear least squares. We conducted transient pulse permeability tests using Inada granite, which is a low-permeability rock, and evaluated its hydraulic constants (hydraulic conductivity and specific storage) using the exact solution of the transient pulse method. We estimated the experimental error between the analytical solution and the experimental data simultaneously. When the approximate solution is used, we can increase precision by considering the compressible storage of the upstream and downstream reservoirs and tubing, which is estimated by a calibration test, instead of considering only water compression. Sensitivity analysis revealed that the sensitivity of the hydraulic head difference between the upstream and downstream reservoirs in terms of hydraulic conductivity is an order of magnitude greater than that in terms of specific storage. This means that the relative error of hydraulic conductivity obtained in a laboratory test is an order of magnitude less than that of specific storage. In precise experiments, control of the room temperature is important because the fluids used in pore and confining lines have thermal expansion characteristics that are sensitive to temperature variation, and the differential pressure transducer is also directly affected by temperature change. The pressure pulse should be as small as possible because if a large change in pressure occurs, the effective stress state of the specimen changes and the permeability changes with it.

This paper reviews the development history of permeability tests for measuring the hydraulic constants (hydraulic conductivity and specific storage) of porous materials in a laboratory, and systematizes the theories of the methods. The permeability test originated from sand filtration experiments carried out by Darcy in the 19th century. Techniques for measuring hydraulic constants were then devised and, at the same time or successively, the theory was established. This paper presents the exact analytical solutions of six methods, including the constant head, falling head, flow pump, and transient pulse methods, with the same initial condition and different boundary conditions. Based on the analytical solutions, we demonstrated the variations in the hydraulic head distribution within a specimen and the variations in the sensitivity coefficients of the hydraulic head difference between both ends of a specimen in terms of the hydraulic constants and compressible storage at the upstream and downstream sides of the equipment during tests of the six methods. The results were used to characterize the test methods, in terms of the experiment time, experiment precision and error, and method selection.

弾性波の分散を利用した岩盤の透水性評価手法の開発を目指し，室内試験および原位置試験による基礎的な検討を実施した。流体で満たされた岩盤中を弾性波が伝播する際には，周波数に応じた固体と流体との相互作用により速度と減衰率が変化する分散現象が生じその周波数特性と透水性との相関性を示す理論が提案されている。本稿では，弾性波の分散と透水性との関係について数値実験を実施し，次いで室内試験を実施した。その結果，透水性の異なる花崗岩試料に対して，異なる分散特性が認められ，理論式と整合することを確認した。さらに，周波数に依存した弾性波速度の分散が原位置で測定可能かどうかを検討した。その結果1.5mから70mの孔間で0.8kHzから80kHzの周波数帯において分散現象の可能性が高い試験結果が得られた。孔間距離1.5mで，発振周波数が20kHzおよび40kHzの弾性波トモグラフィ測定を実施し，地球統計学的手法を利用した試解析により透水係数断面を得た。得られた透水係数断面中央付近のボーリングを用いて透水試験を実施し，推定透水係数と比較したところ，両者の良好な一致が認められた。, The objective of this study is to establish a technique to obtain hydraulic conductivity distribution in granite rock masses. This technique is based on the characteristic that elastic wave velocity disperses in fully saturated porous media on frequency. Velocity dispersion is governed by fluid/solid interaction which corresponds to the hydraulic conductivity such as described by Biot and BISQ theory. In order to verify the validity of these theories in granite rock, laboratory tests were performed. The results of experiments show that the elastic wave velocity dispersion for granite rock can be well described by BISQ theory. To test the applicability of this approach in real rock masses, we performed in-situ experiments at the Grimsel test site in Switzerland. Dispersion phenomena were detected in the frequency range from 0.8 kHz to 80 kHz, in the borehole distance range from 1.5m to 70m. Cross-hole tomography measurements, with frequency at 20 kHz and 40 kHz in a distance between boreholes of 1.5 meter, were carried out. To obtain the hydraulic conductivity image, geostatistical technique was tried. A limited number of hydraulic test data were used to find the correlation between the velocity difference and hydraulic conductivity. With this correlation, a hydraulic conductivity image was constructed. The location of the high hydraulic conductivity zone from the result agrees with that estimated using geological information. Additional hydraulic tests were conducted in a borehole located in the middle of the tomography plane. These hydraulic tests show a good agreement between the measured hydraulic conductivity and the hydraulic conductivities predicted from the cross-hole tomography. These result of experimental studies show that the possibility as a practical method to determine the hydraulic conductivity image in granite rock.

本研究では，粉砕したホタテ貝殻をセメントペースト部分の材料として混入したポーラスコンクリートを作製し，そのポーラスコンクリートの強度特性や透水性に及ぼすホタテ貝殻混入の影響について検討を行った。粉砕した貝殻は粒径が1.2 mm以下のものと1.2 mmから2.5 mmのものの２種類である。その結果，細かいホタテ貝殻を混入した場合に圧縮強度が増加すること，粗いホタテ貝殻を混入した場合に圧縮強度は低下すること，ホタテ貝殻を混入すると空隙率が増加しそれに伴い透水係数が大きくなること，全リンの除去作用にホタテ貝殻の混入は影響しないことが明らかになった。

洗剤の主成分として用いられ, 多量に環境中へ放出されるアニオン界面活性剤は, 有機物で汚染された土壌の洗浄剤としても利用が検討される反面, 細胞膜を破壊する作用があるため, 環境汚染物質としても注視されている. しかし, 土壌中におけるその挙動は解明されていない. ここでは, 腐植物質を多量に含む黒ボク土中における直鎖状アニオン界面活性剤ドデシル硫酸ナトリウム (SDS) の吸着移動現象を明らかにするため, 溶質移動実験と吸着実験を行った. それらの結果は, 単純なイオンの吸着移動とは異なる特徴的な現象を示し, SDSが黒ボク土の腐植成分に協同吸着することを示唆した. 臨界ミセル濃度以下において, SDSの流出濃度曲線の濃度と透水係数の低下がほぼー致し, SDS吸着が透水性低下に影響することがわかった., An anionic surfactant is used in detergents. It has also been tested as a cleaner for soils contaminated with hazardous organic compounds. However, surfactants contaminate aquatic environments because they can destroy cell membranes. Surfactant movements and reactions in soils are not well understood. In this study, we performed surfactant transport and adsorption experiments in soil in order to clarify these phenomena. A linear anionic surfactant, sodium dodecyl sulfate (SDS), and a highly humic volcanic ash soil were used. SDS transport and adsorption showed characteristic phenomena. with the results indicating that SDS is adsorbed cooperatively by the humic substances in the soil. These results were completely different from those for simple anions such as nitrate and chloride. Under a critical micelle concentration, the decrease in the SDS breakthrough curve coincided with the decrease in hydraulic conductivity, demonstrating that SDS adsorption generates a decrease in hydraulic conductivity.

A series of constant head permeability test was performed by putting in a geotextile between a geomaterial layer and a gravel layer in order to evaluate an effect of geomaterial on the cross-plane flow performance of geotextile filter. As the geomaterials for this study, Ataka loam, Kanto loam, Rokunohe sand with fine-grained and Muroran sand with fine-grained were prepared. Based on test results, it was found that the cross-plane flow performance of geotextile depended on the relationship between an amount of clogging per unit volume on each geotextile and a percentage passing by mass of soil particle size less than an opening size of geotextile. It is expected that a clogging mass and an amount of clogging per unit volume are affected by a fiber structure of geotextile.

本研究では、分布型流出解析において用いる分布型モデルの水文パラメータを均質化理論に基づいて定める手法とその適用法について講述する。解析時にはグリッドサイズに応じたパラメータ値になるように定めることが必要である。その際、微小(ミクロ)または肉眼(マクロ)サイズのパラメータ分布情報ならびに分布型流出解析に必要な落水線情報を基にして、それを物理挙動(量的バランス)の整合性が確保されるようにグリッドサイズまで均質化理論でアップスケーリングするという手法を示している。これにより、既往の最も単純な重み付き算術平均パラメータは物理挙動を考慮してない分、不十分な値であることがわかる。, This study proposes a homogenization method of upscaling hydrologic parameters related to a distributed runoff model from macroscopic aspects up to megascopic ones. These parameters are equivalently derived from the mathematically formulated descriptions based on the conservation of surface and subsurface water quantities. A surface flow direction prescribed through a flow direction/routing map is significant to calculate the homogenized values of upscaling hydrologic model parameters. It can be proven that equivalently homogenized parameters stem just from the macroscopic-modeled parameters and the numbers of the longitudinal and its transverse cells, and that a conventional way of equivalent parameters by weighted arithmetic mean is simple and easy but inadequate to figure out.

The apparent opening size (O95) of geotextile is a physical parameter closely related to the permeability property and/or amount of clogging of geotextile. In this study, since the apparent opening size is an important parameter, the apparent opening size test of geotextile on the wet method was performed and verified the adequacy of that test method. The apparent opening size of geotextile obtained from that test is discussed. Based on a series of constant head permeability test results on the various geomaterials carried out in the past, the effect of the apparent opening size on the permeability of the geotextile is also discussed.

本研究では，地下水モデルの透水係数分布同定において，未知数が観測数よりも多いという非適切条件下で事前情報を使った従来手法の逆解析結果と，地球統計学を基に疑似生成した観測データを利用して観測数が未知数よりも多くなるよう条件改善した本提案手法の逆解析結果を数値実験で比較検討した。前者は解の一意性が確保されていないため同定精度は部分的に高くない領域が複数見受けられた。一方，後者は疑似観測データ生成で観測条件が改善されたため解の一意性が確保されて比較的高い同定精度が得られた。以上から，本提案手法は観測条件の改善に寄与して逆解析の適切化がなされ，透水係数分布同定が良好な精度で得られることが確認できた。, This study proposes a mathematical approach to uniquely distributed parameters of an ill-posed inverse problem in hydrology and demonstrates a performance of such an approach through numerical tests by employing geostatistics-generated observation data. For numerical tests, we design a hypothetical aquifer divided into twenty piecewise zones. Twenty permeabilities are individually identified with inaccuracy just through the conventional method using prior information. They are also estimated with well accuracy along the given method of employing observation data generated by geostatistics. It can be proven that the proposed approach is greatly effective and helpful in parameter identification with ill-posedness.

大阪港では更新統砂礫層が厚く、十分な透水性を有しており、k=10^-3cm/s以上の透水係数であれば、その透水性は更新統粘土地盤の沈下性状にほとんど影響しないことがわかった。埋立初期からの更新統全層の沈下実測結果との比較から，更新統砂礫層の剛性はかなり大きく，地下水位低下に伴う有効応力変化によって生じる更新統砂礫層の圧縮量から算定する大倉らの手法で求めた値がパラメータとして妥当であることがわかった。, A series of elasto-viscoplastic finite element analyses is carried out to investigate the effect of the permeability and compressibility of the Pleistocene gravelly sand layers on the stress-deformation characteristics of the Pleistocene deposits in Osaka Port. The relevant procedure to evaluate the rigidity of the Pleistocene gravelly sand layers is also introduced. It is found that the estimation of the elastic shear modulus, G0 as well as permeability of the Pleistocene gravelly sand layers plays a significant role for the settlement prediction of the reclaimed islands in Osaka Port.

廃棄物処分場跡地の高度利用を図るためには構造物の基礎として支持杭を用いることが考えられるが、海成粘土層を底部遮水層としている場合が多く、構造物基礎として杭を打設することによる粘土層の遮水性能への影響について検討を行う必要がある。そこで本研究では、粘土と鋼管杭を想定した粘土-金属の界面における透水性を実験的に評価することを目的として、粘土に作用する鉛直応力および粘土-金属間の密着状態と透水性の関係について検討を行い、粘土と金属の間にフリクションが作用している状態では漏水は生じないことを明らかにした。さらに、実験結果を用いて、杭の打設が粘土層の遮水性能に及ぼす影響について定量的な評価を試み、その評価方法を提案した。, To promote the land use of the coastal landfill site after the waste reclamation, structures and facilities may require pile foundations to assure the sufficient baring capacity. Since the marine clay functions as bottom barrier in landfill sites, it is required to know how much leakage could occur due to the installed piles penetrating clay layer. This research is aimed to clarify the barrier performance with installed piles across the clay layer. Interface transmissivity between the clay and the steel is evaluated by using newly developed rigid-wall permeameter, which is able to determine the side-wall friction by measuring the soil pressures on the top and the bottom of the specimen. The more vertical stress increases, the larger friction between clay and steel occurs and the lower hydraulic conductivity is achieved. It was obvious that leakage could hardly occur from the interface between clay and steel, when friction could work. By using the methods proposed in this research, the hydraulic barrier performance of clay layer with pile foundation can be clearly seen.

本研究では、区域単位に不均質な透水係数分布下の地下水流動に対して、観測水位から分布を同定する際の非適切性を克服する手法を提案した。数値実験では同条件下の仮想地下水流動に対して、区域毎の分布同定結果と地盤統計モデル化による一括の同定結果とで比較検討した。前者の同定精度は非適切条件のため低下したのに対し、後者は非常に高くなった。以上により、本提案手法は逆問題の非適切性を克服し、同定の精度向上にも寄与するとわかった。, This study shows that the distributed pareter modeled herein can improve the effectiveness of solving inverse and ill-posed problems through the numerical experiments. A model structure of distributed permeability to be identified is formed with a geostatistical-based model. A hypothetical aquifer divided into twenty constant-permeability zones is designed. The attempts that twenty permeabilities are piecewisely identified, and that geostatistical-based parameters are identified, are carried out. The former solution is described with part inaccuracy. The latter one is accurately represented. It can be proven that the proposed approach to overcome an ill-posed problem is highly successful in identifying a distributed permeability.

The clarify the permeability of a soil crust, the constant head permeability tests were carried out on the kaolinite and the red soil, and the hydraulic gradient i where Darcy's law was valid and the saturated hydraulic conductivity of crusts mainly examined. For the kaolinite crust, the flux q gradually increased with the hydraulic gradient i, and reached its peak at different hydraulic gradients ranging from 80 to 100 and ended as a down-ward curve. For consolidated crusts at 70 hydraulic gradient of valid region of Darcy's a law, the q-i relationobtained by being tested at the hydraulic gradients below 70 was expressed as a straight line which had the saturated hydraulic conductivity of k=6.80 × 10^cm/s. For the red soil crust, all experimental data points of q and i were approximately on a straight line at the hydraulic gradients below 30, and thus k=2.50 × 10^cm/s was given., 紀要論文

山間部峡谷に堆積した土砂地盤の流出特性を知るため、原位置浸潤試験により地盤の透水性を調べた。調査サイトは、斜面崩壊土が流下し、峡谷の河川敷に堆積した地盤で、大きな礫の問に小礫まじりの砂が分布する。試験にはゲルフ式プレッシャーインフィルトロメータ(GPI)法を用いた。簡便で迅速な原位置試験法であることから、比較的多くの測定データが得られ、調査地盤の透水性を適切に評価することができた。礫を含む地盤の透水係数の評価法を提示し、堆棟地盤からの流出特性に及ぼす礫の影響を検討した。, Permeability of sand sediment soil was measured by using itl-situ infiltration test to predict amount of runoff from the soil subject to heavy rainfall. The debris flow had sedimented onto river bed to form the soil between narrow valley. The soil was sand mixed with small to large gravel. A Guelph pressure infiltrometer (GPI) was employed to measure field-saturated hydraulic conductivity of the soil. The GPI method was effectively applied to measure the hydraulic conductivity of the soil quickly and easily. A physical model to determine of hydraulic conductivity of soil taken account of gravel content was proposed. Effect of gravel conteilt Oll the runoff amount from the soil was examined by using saturated-unsaturated seepage analysis.

処分場遮水構造において重要な機能を発揮するのは, 低透水性が保持できる材料で構成するバリア層である。よって, 遮水工の設計では底部ライナー, およびカバーシステム内バリア層の透水性の評価が重要となる。本研究では, 廃棄物である製紙汚泥および掘削汚泥を処分場バリア材へ有効利用するため, 遠心模型実験を実施し, 汚泥の有する透水性能, および圧密特性の10年間に及ぶ長期挙動を検討した。結果の一例として, 製紙汚泥は, 60G場において10-7cm/sオーダーの透水係数を24時間にわたって維持でき, 実際にバリア材として用いた場合, 約10年間はその透水性を維持できる結果を得た。, In design of the landfill water interception structure, evaluation for hydraulic conductivity of barrier layer in cover and bottom liner is the most important task. In this study, in order to reuse paper sludge and construction sludge to landfill barrier materials, long-term hydraulic conductivity and consolidation characteristic of sludges were examined using geotechnical centrifuge. As the results, PS could retain the hydraulic conductivity of the order of 1.0x l0-7 cm/s in the 60 G field for 24 hours. This result comprises that, when PS was used as barrier material in the field, the hydraulic conductivity of 1.0x10-7 cm/s will maintain for 10 years.

圧密支配方程式の数値解析では、材料パラメータは圧密進行中において一定として扱われることが多い。しかしながら、圧密は、間隙水の排水を伴いながら間隙の有効径を縮小し、土粒子骨格をより密な構造へ移行させる過程である。したがって圧密過程では、間隙水の流れと土粒子骨格構造の変形を支配するそれぞれの構成モデルは、当然のことながら非線形モデルとして扱わざるをえない。圧密の進行に伴う間隙比、透水係数および体積圧縮係数の変化を調べるために、正規圧密粘土を使った圧密～透水試験を行った。この試験結果に基づき、透水係数を間隙比（体積ひずみ）の関数として表現した間隙水の流れに関する非線形構成モデルを示した。また、土粒子骨格の弾性係数を静水圧有効応力の関数とした非線形構成モデルを示した。さらに、これら２つの構成モデルを組み込んだ三次元圧密プログラムによる２・３の解析例を示し、線形との比較および考察を行った。, In the numerical analysis of the consolidation governing equation , a material parameter treated as constant in process of consolidation progress. However, it is considered that the governing equation should consider non-linear of material. For the purpose of relating the change of the permeability in the progression of the consolidation to the void ratio , the consolidation and permeability tests is carried out to normal consolidated clay. The non-linear constitutive relation between permeability and void raitio and Young’s modulus defined a function of effective hydrostatic stress was applied to three-dimensional consolidation program. Compare the non-linear analysis results with the linear was examined.

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.

廃棄物処分場に設けられるカバーシステムの主要な目的は, 降雨の廃棄物層への浸透を最小化することであり, カバーシステム内バリア層の低透水性の確保が重要因子となる。これまで著者らは, バリア層への汚泥の適用性を室内試験より明らかにしている。本研究では, バリア層へ汚泥を適用したカバーシステムにおける降雨遮水効果を水分収支モデルによって明らかにするものである。その結果, 透水係数1×10-7cm/s, 層厚10cm以上を確保できるバリア層を有するカバーシステムであれば, 日本各地の気象環境下で, ほぼ全量の降雨が遮水可能な結果が得られた。, The purpose of landfill cover system is to minimize the infiltration of rainfall into the waste layer using a low hydraulic conductivity barrier layer.In this paper, the application of sludge materials to the barrier layer of cover system through laboratory study has been evaluated. The rainfall water interception effect in a cover system that applied to the barrier layer using sludge materials has been verified using the water balance model results. Further, the rainfall interception effect of the proposed cover system has been studied using a barrier layer of 10 cm thickness and hydraulic conductivity, 1 × 10-7 cm/s for various climatic environmental conditions in Japan.

近年, 我が国では廃棄物処分場における残余年数の切迫等により, 廃棄物の有効利用が積極的に行われている。そのような状況下, 本研究では廃棄物である汚泥材料の廃棄物処分場カバー材としての適用性を検討するものであり, 汚泥材料として製紙汚泥および建設汚泥に着目した。室内試験では, 汚泥材料の工学的諸特性, 透水試験, 圧縮試験, およびせん断試験を実施することでカバー材としての安定性を検討した。さらに, 廃棄物の有効利用に伴う環境影響評価として, 透水試験後の排出液中の有害物質含有量分析を行っている。結果として, 製紙汚泥, 建設汚泥とも有効利用に伴う環境適合性は満足しており, さらにカバー材として要求される機能を十分に有していることを明らかにした。, The objective of this paper is to examine the material properties of paper mill sludge (PMS) and construction sludge (CS) as landfill cover materials. Hydraulic conductivity, physical and engineering properties, and chemical analysis of effluents were investigated to evaluate the suitability of PMS and CS for cover application. X-ray diffraction and scanning electron microscopy analyses have been carried out to evaluate the mineralogical and microfabric arrangement of PMS and CS samples. The test results indicate that both PMS and CS fulfill the landfill cover requirements and encourage their utilization as alternative materials.

耐化学性ベントナイトである多膨潤性ベントナイト(mutiswellablebentonite:MSB)の, 廃棄物処分場バリア材への適用性を実験的に検討した。MSBは塩化カルシウムや塩酸の溶液に対しても高い膨潤性を示し, 透水係数も天然ベントナイトより1オーダー以上低い値が得られたことから, 廃棄物処分場のライナーやカバーなどのバリア材に有効に適用しうることが示唆された。, Chemical compatibility of a newly developted material -multiswellable bentonite- is evaluated for the purpose of landfill barrier application. A series of liquid limit, free swell, and hydraulic conductivity tests were performed. The materials used in this study are natural bentonite and multiswellable bentonite. The permeants are distilled water, and CaCl2 and/or HCl solutions. Electrical conductivity and pH values of the effluents obtained from the hydraulic conductivity tests were measured to ensure the total chemical breakthrough. Multiswellable bentonite was found to perform better than natural bentonite does when in contact with CaCl2 and/or HCl solutions. Values of free swell and liquid limit of both bentonites decreased with the increase in concentration of CaCl2. Most specimens of multiswellable bentonite had the hydraulic conductivity one or more orders of magnitude lower than that of natural bentonite when in contact with the same concentration of CaCl2 solutions. The hydraulic conductivity values of both bentonites are higher than the requirement by the US EPA for MSW landfill clay liner (k < 10-7 cm/s) when permeated with calcium chloride solution greater than 0.3 M.

1) 浸入能はクラストの形成によって大きく抑制された。2) クラスト地における土壌表層(0&acd;5cm)の透水係数が3土壌とも低い値となった。また,クラストが土壌の透水性に及ぼす影響が裸地区において著しいことが認められた。3) クラスト地における土壌表層で,粘土・シルト分が多いことから,クラストが分散土粒子によって形成されることが認められた。4) 植生区では,土壌表面が被覆物によって雨滴の衝撃から保護されるため,クラスト形成が時間的に遅延されることが示唆された。, While crust was formed on the soil surface, seed germination rate and the infiltration of rain water would be reduced, and then prompt to produce more runoff induced soil erosion. Therefore, it is very important to study the crust formation mechanism for establishing the countermeasure for controlling soil crust. In this paper, approaches were made to examine the crust formation mechanism of Kunigami-mahji, Jahgaru and Shimajiri-mahji soils. Infiltration capacity of soil could be greatly reduced by the formation of crust. Hydraulic conductivity of crusted topsoil (0-0.5cm) was less than that of three soils mentioned above. The topsoils contained much more silt and clay particles. In vegetated plots, mulching protected soil surface from raindrop impact, so the formation of crust was delayed., 紀要論文

雨水によるクラストの形成に伴う土壌表層の透水性と粒径組成の変化について検討し,以下の結果を得た。(1) 濁水の湛水に伴う土壌表層の透水係数(k)の変化については,150ppmにおいてk=1.33・(10)^cm/s,250ppmにおいてk=8.85・(10)^cm/sとなり,湛水前のk=3.61・(10)^cm/sよりも大幅に低下し,堆積クラストの形成が認められた。(2) 雨滴の衝撃に伴う土壌表層の透水係数(k)の変化については,降雨前のk=3.36・(10)^cm/sが,20分降雨後にk=1.23・(10)^cm/s,40分降雨後にk=3.09・(10)^cm/sとなり,構造クラストの形成が認められた。(3) また,土壌表層では雨滴の衝撃に伴って,粗砂・細砂の粗粒分の減少があり,飛散による影響が認められた。なお,雨水によるクラストの形成については,透水係数や粒径組成の変化による検証のみでは不充分であり,更に追究し,そのメカニズムを明らかにする予定である。, Approaches were made to examine the variation of infiltration capacity and particle size distribution of soil in the crusting process induced by rainfall in this paper. Following the accumulating of clouding water, the hydraulic conductivity (k) of soil surface greatly decreased from 1.33×(10)^cm/s before watering to 3.61×(10)^cm/s and 8.85×(10)^cm/s respectively for the cases watered with 150ppm and 250ppm clouding water. It reveals that a kind of accumulated crust had been formed. Furthermore, the hydraulic conductivity varied with the compaction of raindrops. Before the rainfall started, k was 3.36×(10)^cm/s, and then it declined to 1.23×(10)^cm/s and 3.09×(10)^cm/s at the times of 20 and 40 minute after raining. It could be confirmed that a kind of structural crust had been developed. Also, impacting of raindrops reduced the coarse and fine sand fraction on soil surface due to the influence of splashing., 紀要論文

さんご礁におけるさんご砂やさんご礁からなる堆積物の透水係数とそれに及ぼす間隙比,粒度,礫含有量,粒径,75μm以下粒径含有量等の影響を検討した。主な結論は次のようである。1) 透水係数(K)は間隙比(e)に支配され,ln(K)とeの間に線形関係が認められる。2) さんご砂では礫含有量の増加に伴って透水係数が増大し,礫混じりさんご砂の透水係数は礫含有量の影響が大きい。3) 一方,同じ礫含有量のさんご砂においては透水係数に及ぼす礫の粒径の大きさの影響は小さい。4) さんご砂の透水係数はシルト以下の細粒分の含有量による影響が大きい。5) さんご砂礫層の透水係数は堆積物を構成する粒子の有効径から推定できる。6) さんご砂礫層の透水係数は,粒径75μm以下の含有量が5%以上であれば(10)^cm/sのオーダの範囲にある。, Calcareous sediments consist of such bioclsatic as coral, shell and foraminifera, which have calcareous skeleton. A series of permeability tests has been performed on reconstituted calcareous sands with various grading curves to clarify the effects of grain size, content of gravelly component and fine fraction smaller than 75μm on the coefficient of permeability. Major conclusions obtained in this study are as follows. (1) There exists a liner relation in the relationship between the logarithm of the coefficent of permeability and void ratio ratio for individual grading curves. (2) The equivalent coefficient of permeability in a give void ratio increases as the content of gravelly component increases. (3) On the other hand the coefficient of permeability decreases with the increasing in the fine fraction smaller than 75μm. (4) Based on characteristics of gradation the coefficient of permeability of calcareous sediments can be estimated to be within the range of (10)^cm/s. (5) The coefficient of permeabioity of calcareous sands can be evaluated by using the effective size D_., 紀要論文

安山岩類の風化残積土である久米島土の土質材料としての適応性について, いくつかの性質を他の国頭マージと比較しながら検討してきた。これらのことから, 次のことが結論ずけられる。1.久米島土は, 国頭マージの中でも最も粘土粒子を多く含む(0.005mm以下粒子75%)土である。2.標準締固め試験で得られる乾燥密度は, P_dmax=1.26g/cm^3程度で非常に低く, 締固めエネルギーを増してもその効果は薄い。また最適含水比も40%に近く, 高い値である。3.圧縮指数は0.34程度で圧縮性の土と云える。4.遮水性には富むが, 団粒構造の結合が強く, 圧密荷重51.2kgf/cm^3までかけても, 団粒は破壊せず, 透水係数はばらつく。5.締固め土の密度は低いが, 一軸圧縮強さは普通程度の値が得られ, 変形係数も大きい。しかし, D_のφ_uの値が最適含水比と比べて極端に低下する。以上の他に, 地山の自然含水比が高く, 現場での含水比の調整が困難であるなどいくつかの問題はあるが, 低ダムの築堤用土としては十分に適合するといえる。, Kunigami Maaji, which can be found in the Ryukyu Islands, is principally a red residual soil, frequently used as fill material in this area. In this rocal soil, kumejima soil which is residual soil of andesite, has a different physical and engineering properties comparatively with usual kunigami Maaji. In this report, the characteristics of compacted Kumejima soil and their application to the fill material were investigated. The results obtained are as follows. 1. The soil belongs to clay, and includes the clay perticles of 75 percent. 2. Values of the specific gravity are relatively small in Kunigami Maaji. 3. Maximum dry density is low in degree of 1.25g/cm^3,and even if the compaction energy increase, it increases a little in dry density. 4. Optimum moisture content is high about 40% and natural moisture content is higher 5-10% than optimum moisture content. 5. Compression index is large, there fore its soil structure may be compressibility., 紀要論文

国頭マージの中で一般的である千枚岩風化土について, 礫を混合した場合の混合土の密度, 礫以外の部分の密度の変化および礫の粒径を変えた場合の土の密度の変化などについて実験をしながら, 同時に透水係数の礫率による変化を調べた。礫混合どの場合, 礫率が増すと土全体の密度は高まり, 締固めた土の強度が増すことは一般的に判断される。しかしこの土を遮水材料として使用する場合は, 礫を混合する時の透水係数の増大が問題になる。この実験の結果から, 礫率が増加するにつれて礫以外の部分の密度は低下し, 透水係数も大きくなることを示した。また礫率が同じであれば, 混合に使用する礫の粒径が大きいものほど混合土の密度は大きくなることが分かった。また透水の難易を支配する礫以外の部分も, 礫の粒径が大きいものほど大きい密度を示すことが分かった。このことは, 礫混合土における透水係数の増大は, 単に礫同士の噛み合いによるだけではなく, 礫の表面積の大きさ, いいかえれば礫が押し込まれるときの全体としての表面積が小さいものほど, 礫以外の部分の密度が低下しないことになる。また, 室内試験における締固めエネルギーの大きさの, 現場に於ける対応については, 前述のように支配要素は多すぎるが, いくつかの条件を固定すればある程度の目途は立つものと考えられる。, Cohesive soils are frequently mixed with gravelly soil for soil improvement. Soil materials are improved in soil mechanics by mixing gravelly soils. But in a case of materials used as a core of fill dam, it is necessary for compacted soil to be impervious. In this paper, the dry density which is separated the part of excepting gravel from gravelly compacted soil were investigated. The results obtained are as follows. 1. The values of dry density and coefficient of permeability of compacted soil increased with the increase of gravelly ratio. 2. Dry density in the part of excepting gravel contrarily decreases with the increase of gravelly ratio. 3. It seems that the dry density of gravelly soil depends on size of gravel and specific surface area of gravel in the same gravelly ratio., 紀要論文

Slush avalanches and debris flows often occur on the slope of Mt. Fuji. It is common that the shear plane exists in the upper thawed soil layer on the frozen soil layer. As the permeability of the frozen soil layer is extremely low in comparison to the upper thawed layer, ground seepage can easily develop during rain fall. Therefore, the instability condition of the slope is obtained mainly due to the seepage force developed in the thawed soil layer. This report describes the summary and results of a model experiment in relation to the mass flow, using soil samples obtained from the slope of Mt. Fuji. The result show that the slope stability problem of Mt. Fuji can be solved with the conventional analysis being used in geotechnical engineering, if the seepage forces are properly estimated. For the prediction of slush avalanches, the following factors are at least needed: (1) thickness of thawed soil layer and depth of frozen soil layer, (2) thickness of snow deposits, (3) water level in thawed layer, and (4) slope angle.

本研究では，沖縄島に分布する年代や岩相の異なる2 種類の石灰岩地域の湧水地点において約半年間にわたり水文観測を行なった．その結果，多孔質な第四紀琉球石灰岩地域にある志喜屋の湧泉と緻密な古期石灰岩地域にある具志堅大川との間には，降雨流出特性や水質に違いがみられた．基底時における単位面積あたりの流量は，古期石灰岩地域のほうが多く，カルシウムイオン濃度は琉球石灰岩のほうが高かった．また，降雨イベント時の流量変化をみると，具志堅大川では，台風接近時の300 mm を超えるような，暴風雨時にのみ流量に大きな変化が現われ，一方，志喜屋の湧泉では，数10 mm から数100 mm にいたるほとんどの降雨イベントにおいて降雨に速やかに対応した流量の増加がみられた．また，降雨イベント時における流量の減衰は，具志堅大川では，1 日程度と速やかであるのに対し，喜屋の湧泉では，定常時の流量に戻る期間は数日から数週間を要し，ピーク流量の値が大きいほどその時間は長かった．このような違いは，具志堅大川では，岩体の割れ目だけが主な水の通り道となっているのに対し，志喜屋の湧水では，琉球石灰岩自体の透水性が高いために，割れ目だけではなく岩体自体が風化層のような役割をしたためであるとともに，地質構造の違いによる地下水システムの違いによると考えられた．

細粒分含有量5&acd;84%のさんご礁堆積物について変水位透水試験を実施し, 透水係数に及ぼす細粒分含有量の影響について検討した。主な結果は次のようである。1) 細粒分含有量20%以上においては細粒分含有量と平均粒径との間に相関性が認められる。2) 透水係数の対数(In k)と間隙比eの間には線形関係が認められ, その傾きは細粒分含有量の増加にともなって増大する。3) 細粒分含有量20%以上では透水係数は(10)^&acd;(10)^(cm/s)のオーダーにある。4) 細粒分含有量が増加すると, 透水係数kはe^3/(1+e)と比例関係が成立しなくなる。5) 透水係数は細粒分含有量の増加にともなって減少する。6) さんご礁堆積物の透水係数は細粒分含有量から推定可能である。, A series of variable-head permeability tests has been performed on reconstituted carbonate sand with various fraction finer than 75μm. Major conclusions obtained in this study are as follows. (1) There exists a liner relation in the relationship between the logarithm of the coefficient of permeability and void ratio for individual fraction content. (2) The value of permeability ranges between (10)^3cm/s and (10)^4cm/s for sands contained fraction more than 20%. (3) The relationship between the coefficient of permeability k and the content of fraction is derived in a given void ratio based on the liner relation for ln k versus void ratio e. (4) The coefficient of permeability of carbonate sands can be evaluated by using fraction finer than 75μm., 紀要論文

ソイルセメントの収縮量は施工後1週間程度進行する。特にブリージングと初期硬化が起こる1日目の収縮が4～5%と極端に大きい。この収縮率を現行の地下ダムに適用すると、連壁の高さを60mとすれば2.4～3.0mに相当する連壁の高さが施工の翌日までに落ち込むことになる。この高さは明らかにダムの洪水吐の高さ、あるいは総貯水量に大きな影響を与えることになるので、施工時に収縮量を考慮した高さとしておくよう十分な配慮が必要である。また、施工中の材料分離や地下水の混入によってソイルセメントの水セメント比や磯率が大幅に変化するようなところでは透水係数や圧縮強度が変化することも考慮しておく必要がある。さらに、地下ダム連壁に打継目が存在することは、地震の場合に地盤の揺れに同調出来ない打継目で連壁に亀裂が生じることになる。連壁の連続施工ができるまでは連壁の打継目は補間杭などによって補強するなど、それなりの対策を講じて対処する必要がある。本研究を進めるに際し、資料収集から実験材料の提供までいろいろとご協力を頂いた沖縄県南部農林土木事務所のカンジン地下ダム担当の方々、実験にご協力頂いた元専攻生の原園智子、北村知周、嶺井志麻、仲村裕志の各氏に謝意を表する。, In the construction of continuous underground wall by SMW (soil mixing wall method), three problems have been indicated. The first is to generate the shrinkage settlement under curing. The second is that engineering properties change under construction by material separation of soil cement and contamination of the groundwater. The third is that many cold joints occur. Therefore, the shrinkage behavior of soil cement during water curing period was examined, and next, expression process of hydraulic conductivity and compression strength of soil cement were clarified, and the effect of gravel rate and water cement ratio on them was examined. In addition, permeability test and shear strength test were carried out on the cold joint model test-pieces. Then, hydraulic conductivity and shear strength of the cold joint in soil cement were clarified. Finally, the some countermeasures for the construction of continuous underground wall were proposed., 紀要論文

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