Leakage of water due to internal erosion through a dam body or foundation is a major problem with fill-type dams. Recent case histories and research suggest that most cases of internal erosion are possibly triggered by hydraulic fracturing. However, the quantitative mechanism of hydraulic fracturing still remains to be solved. Therefore in-situ hydraulic fracture tests were carried out with a cheap, concise apparatus using boreholes dug in the soft clayey volcanic soil foundation of a low earth dam (Oyachi Dam) in Niigata Prefecture. Water was injected into the foundation through a perforated pipe by two methods : one was under a controlled injection pressure and the other was a controlled injection flow rate. In the former method, the relationship between flow rate and injection pressure was observed and it was found that a yield pressure or fracture pressure existed in all the tests. By repeating the injection test it was confirmed that once a crack is developed, it is very easily reopened by a water pressure a little higher than the earth pressure exerted on the crack. In the latter method, the relationship between injection pressure and time was observed and it was found that fracture pressure varied with flow rate. The boreholes were excavated to observe the development of fracture cracks and it was also found that the cracks had developed perpendicular to the borehole periphery, which means that fracture cracks were induced by tensile stress and denies the explanation that fractures are caused by shear failure.

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A comparative study of the static and dynamic response of a slope is carried out, using the large deformation theory of the updated Lagrangian formulation and the conventional infinitesimal theory. In the static analysis, a strength reduction method proposed by one of the authors is used to evaluate the safety factor of the slope. It is found that by the large deformation theory, the safety factor is larger than that calculated by the infinitesimal theory, and this difference becomes large along with the reduction of elastic modulus. In the dynamic analysis, it is observed that the large deformation theory gives smaller sliding displacement and larger response acceleration than the infinitesimal approach. It is concluded that in many cases the large deformation approach gives more adequate solutions.

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The performance of single pitch and multi pitch screw anchors during the application of installation torque is presented. An experimental testing program was conducted using five models of screw anchors with different geometry. The effect of the shape of the screw element, sand properties, and installation depth on the required installation torque value was examined. A theoretical model was developed from which the required installation torque value can be calculated in terms of the influencing factors. The required installation torque can be determined in terms of the ultimate uplift resistance calculated from any of the available theories. Based on the actual installation torque value measured in the field, the anticipated pullout capacity can be back calculated from the present theory. A comparison between theoretical and experimental results showed good agreement. Also, good agreement was observed when the present theoretical results were compared with the available field results reported in the literature.

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Based on the concept "intermediate soil wedge" which is dependent on mobilized frictional resistance, a new theory has been developed for evaluating the seismic earth pressures against retaining walls under any condition between the active and passive states. For this theory, the seismic earth pressure is separated into four components according to their formation. New equations are proposed to determine the distribution, resultant and point of application for each component. An equivalent seismic coefficient is introduced to take into account non-uniform seismic acceleration distribution with depth. The equations place special emphasis on dependence of the seismic earth pressure on mode and level of wall movement. The equations can be reduced to the Mononobe-Okabe equation for the limiting conditions. Their applicability was confirmed by comparing the predictions with a number of previous model test results.

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During earthquakes, saturated loose sandy soils often liquefy, causing serious damage to buildings and underground structures. Various construction methods have been employed to stabilize these soils against liquefaction. The popular methods are those which increase their density. Vibration and impact methods are commonly employed, but these often pose a problem of noise and vibration in urban areas. Results of previous experiments have shown that Quick Lime Consolidated Briquettes (QCB), a soil stabilizer made of quicklime and cement placed to form cylinders, significantly increases resistance to liquefaction by utilizing the effects of water absorption, swelling, and hardening. In the present study, shaking table tests were performed to evaluate the earthquake resistance of soil treated with QCB. Results of these test showed that the response acceleration and excess pore water pressure in QCB-treated soils were scarcely affected by the excitation of 200 Gals. The soil settlement due to shaking was about one tenth of that for the untreated soil, proving the effectiveness of QCB during earthquakes.

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A finite element model capable of taking into account nonlinear hysteretic soil behavior is presented to study earthquake induced retaining wall movement. The model also accounts for increase in lateral stresses and settlement associated with grain slip caused by cyclic loads. The predictive capability of the proposed method is verified by comparing responses given by the model with those computed by another existing finite element model and also with responses recorded at the Cambridge centrifuge facility. The study reveals that the wall displacement can be substantially affected, among other factors, by the increase in lateral stresses due to grain slip and wall-soil friction. Care should be taken when selecting a constant value of wall-soil friction angle for the entire duration of excitation since structural changes can occur in the soil adjacent to the wall.

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The effects of the pressure of ambient gas and sample temperature on photo-acoustic displacement (PAD) were studied quantitatively using an extremely sensitive laser interferometric probe. For silicon, the PAD signal measured at atmospheric pressure increased by about 18% as compared to that obtained in a vacuum, and varied by less than 0.7% for a change in pressure of % around 1 atm. This effect was attributed to the decrease in refractive index of the gas adjacent to the sample. Temperature rise caused PAD to increase proportionally, and for GaAs, PAD varied 0.% per degree. The variation of PAD with temperature was accurately explained by the temperature dependence of thermal expansion coefficient and thermal conductivity of the sample.

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Circuit techniques to enhance the linearity of input-voltage-to-current (V/I) conversion and to increase the output impedance of a current source by compensating for the low intrinsic gain of a transistor were introduced to realize a high-frequency operational transconductance amplifier (OTA) for a low supply voltage using sub-100-nm CMOS processes. Applying these techniques, a MOS 7th-order Gm- linear-phase low-pass filter (LPF) was realized using a 65nm CMOS process. A simplified biquad LPF that can serve as a component of a 7th-order LPF was newly developed by replacing OTAs with resistors. As a result, the -3dB frequency bandwidth, group delay ripple, 3rd-order distortion, and 3rd-order input intercept point (IIP3) were 200MHz, 2.2%, ≤ -55dB with a 100MHz input, and +10.3dBm, respectively, all with a ±0.1Vp-p input signal at each input terminal in the pseudodifferential configuration. The LPF including an output buffer dissipated 60mW in the case of a 1.2V supply. Wide spurious-free dynamic range (SFDR) characteristics were confirmed up to high frequencies.

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　本研究では，空石積みの修復活動のオーガナイザーに半構造化インタビューを行い，参加者がいかにしてオーガナイザーになるのかを把握し，さらに継続的に活動を続ける可能性が高まる場のマネジメントの在り方について考察した．その結果，オーガナイザーに共通する前提として類似する石積みに対する思いと活動を取り巻く環境を有していることなどが分かった．また，活動を実践することによる変化の特徴として様々な役割を果たさざるを得ない実践を経験したこと，即興的なコーディネート，ルールの原則の理解，修復作業のアレンジという

つの特徴が見られた．これらより活動のマネジメントとして，役割分担を固定しない，ルールの優先順位の伝達，雑談を促すの3つを示した．

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　ラオス国のナムニアップ1水力発電プロジェクトに関わる少数民族モン族3,500人の移転に際し，住民の強い反対に直面し，同意取得と移転完了に至るまでに多大な労力と時間を要した．反対の理由として，移転地の土壌の品質と，山間における焼畑と狩猟・採集を主とする循環型から，平地における水田耕作による定住型の農業形態への移行に対する不安が影響した．この対処として，事業者は移転地内にパイロットファーム（実験農場）を開設し，住民を招待して土壌改良や農業技術の指導を試みた．本論文では，パイロットファームにおける移転計画の実証や情報伝達，フィードバックの効果，ライフスタイルの変化に伴う新たな生産活動を創造する場としての可能性について論じるものである．

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　本研究は，公共交通のサブスクリプション型運賃は持続可能なのか，採算が取れるのか，導入の意思決定は如何に行われたのかを明らかにするため，筑波大学と小山市におけるエリア乗り放題格安バス定期券の導入プロセスと効果を分析した．筑波大学は，学内交通環境改善検討の結果，大学がバス事業者から1年間有効の定期券6千枚を一括買取りし，大学構成員に再販することで

割引を実現して17年間サービスを継続していた．小山市は，市民のバス利用促進を目的に市内全線定期券の7割引を決断し，販売期間を暫定1年として，延長して2年間サービスを継続，減収が無いため恒久サービスに転換していた．両事例には，公的主体による収入保証，モビリティ・マネジメントの継続と定期券購入者増加，地域の協働などの共通点があった．

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