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本論文は，数理弁証論理（MDL）ベースのモデリングを行う。中国の黄土高原地域の流域を対象に，測定データを使用して斜面侵食リモート・センシング情報モデル（RSIMWEH）―MDLベースの侵食モデルにより土壌浸食量を計算する。シミュレーション結果はRSIMWEHが土壌と水保護の実務に有用であることが示される。, This paper discusses mathematically dialectical logic (MDL)-based modelling idea. Selecting one watershed in China Loess Plateau region as research object, the authors calculated erosion from the watershed by using Remote Sensing Information Model of Water Erosion on Hillslopes (RSIMWEH), a MDL-based erosion model using measured data. The simulation result shows that RSIMWEH can serve the practice of soil and water conservation.

飽和砂地盤上の盛土の動的変形挙動を調べるため，遠心模型実験，および多重せん断ばねモデルによる有限要素解析（FLIP）を行った．本研究で対象とした盛土は，堤体高さ3ｍ，天端と下端の長さが4ｍと11.5ｍ（実物スケール）である．また下部地盤の層厚は5ｍである．緩詰地盤を対象とした数値解析では地盤のN値=1に対応するパラメータを用いた場合に，天端の沈下量が実験結果と良く一致した．数値解析の結果，入力加速度が大きいほど，盛土下部の非液状化領域が大きくなり，それがくさびとなって周辺の液状化地盤を押しのけるため沈下量が大きくなるという，一見すると直感的ではない変形メカニズムが推察された．, Dynamic behavior of an embankment (3 m height) made of dry sand underlain by saturated sand deposit with 5 m depth are studied. Firstly, centrifuge experiments under 50 G are conducted. The relative density of saturated sand deposit is approximately either 30 % or 70 %. Sinusoidal input motions with various levels of peak acceleration amplitude are employed. Test results show that the maximum settlement was 1.4 m and 0.09 m, respectively, for loose and dense deposit. The amount of settlements for dense deposit are found to be proportional to the peak amplitude of input acceleration, while it may have a plateau for the case of loose deposit with increase of input acceleration amplitude. Following the centrifuge experiments, an effective stress analysis is carried out with the same prototype dimension of the experiments. The numerical analysis simulates well deformations and transient motions of the experimental counterparts. It is found that, in the analysis for loose deposit, when input acceleration increased, non-liquefied area underneath the embankment became large, causing larger non-liquefied wedge pushing liquefied soils aside.

杭―地盤相互作用に伴って生じる水平断面内での杭周辺地盤の変位・変形性状を詳細にとらえることを目的として模型実験を行った。実験した断面について，数値シミュレーションも実施し，模型実験から得られた結果の一般化を図った。数値シミュレーションにおいて用いた砂の力学モデルは，多重せん断機構に基づくモデルである。乾燥排水条件では，杭周辺の地盤変位ベクトルは杭前面では杭変位と同じ方向に，また，杭の側面では杭表面からの距離に応じて急速に変位が小さくなる傾向を示した。飽和非排水条件では，杭側面で渦状の変位形態が見られ，杭の前後では，それぞれ押出し，引込みの変位形態を示した。杭間の変位は，杭表面付近にひずみが集中する傾向が見られた。, Two dimensional model tests are performed on a horizontal cross section of a soil-pile system in a pile foundation. The objective of the model tests is to evaluate local soil displacement field in the vicinity of the piles associated with a global displacement of soil around the pile foundation. Two dimensional effective stress analyses in horizontal plane are also performed to generalize the findings from the model tests. An effective stress model based on multiple shear mechanism is used through a computer code FLIP. In dry condition, displacement vectors are directed away from pile front, and displacement at pile side rapidly decreases with an increasing distance from soil pile interface. In undrained condition, displacement field shows vortexes at pile side associated with push-out/pull-in pattern of displacements in front of and behind the pile. Distribution of local soil displacement between piles shows high strain concentration at soil-pile interface.

本研究の目的は，地盤内間隙水圧の波浪応答に関する数値計算の結果と，防波堤での現地観測によって得られたデータとを比較することによって，高波浪時における地盤内間隙水圧の波浪応答を明らかにすることである。本研究では，波と構造物，地盤の動的挙動を同時に解析することができるVOF-FEM 法を改良し，地盤部の弾塑性解析を可能にした。土の塑性に起因して生じる残留ひずみを表すことができたが，土の繰り返し塑性に起因して生じる残留間隙水圧を再現するには到らなかった。, The present study investigates the response properties of pore water pressures in the seabed beneath a composite breakwater armored by concrete blocks. In order to compute residual pore water pressures, the VOF-FEM model is modified by introducing the elasto-plastic constitutive model which involves the rotation of principal stress axes. It has been revealed that the motions of the coastal structures due to wave loads strongly affect the response properties of pore water pressures in the seabed beneath the coastal structures like the caissons and the concrete blocks.

2004 年は多くの台風が日本に上陸し，各地に甚大な土砂災害を引き起こした。ここでは，その中から台風10 号による徳島県木沢村および台風21 号による三重県宮川村（現大台町）での斜面崩壊等の土砂移動現象に着目して，それらの発生メカニズム，土砂移動現象の特性などについての調査結果と解析結果について述べる。とくに，現地で観測された段階的崩壊プロセス，地下の集水構造と土砂移動の関係，崩壊過程の違いによる天然ダムの規模の違いについて焦点を当てて報告する。, In 2004 a lot of typhoons attacked the Japanese Islands and they caused a lot of sediment related disasters. Among them, we have investigated the sediment disasters in Miyagawa Village by Typhoon 21 and in Kisawa Village by Typhoon 10 and collected the information on the process of some slope failures and the characteristics of bedrock feature. In this paper, we analyzed the water movement in the slopes and its role on the slope failure, the phased failure process observed in Kotaki, the influence of the phased failure on the formation of landslide dam. As a result, a numerical simulation could explain the phased slope failure in Kotaki, and a hybrid-debris flow model could show such a slope failure process produce the difference of height, width and length of landslide dam.

高波浪時における海底砂質地盤の応答を調べるため，海底地盤上の水圧と地盤内間隙水圧を系統的に観測した．また，VOF-FEM による数値計算を実施し，間隙水圧の波浪応答について観測結果と比較した．現地観測の結果，残留間隙水圧の長周期変動成分は，来襲波浪の波群特性に関係していることがわかった．また，上載構造物下の地盤内における間隙水圧の位相差を含んだ時系列変動は，波浪作用によって生じる構造物の運動に起因していることを数値計算で明らかにした．液状化については，構造物による上載圧の増加を考慮すると，法先自由地盤を除いて，発生する可能性は極めて低いという結論に達した．, The purpose of this study is to clarify the response properties of pore water pressures in the seabed beneath a composite breakwater. The build-up of residual pore water pressures was found in the sandy seabed during the storm waves. It has been revealed that the response properties of residual pore water pressures are closely related to the wave grouping characteristics of the specific wave periods. It was clarified that the possibility of liquefaction occurrence was extremely small except the free seabed at the toe of foot protection considering the loading stress of the structures.

近畿地方の南北縦断測線(新宮―舞鶴測線)において，制御震源を用いた大規模な広角反射法・屈折法地震探査による大深度弾性波探査を行った。この結果，フィリピン海プレートの構造と地殻全体の速度構造が求められた。プレートの沈み込みは，近畿北部まで達しており，地域によってプレート面からの反射率が変化することがわかった。紀伊半島の南部で反射率が弱くなるところがあるが，これはプレート境界面のアスペリティ構造に関連する可能性がある。さらに，低周波地震発生域付近では反射波が部分的に見えなくなる。また，有馬高槻構造線を横断する測線で反射法探査を実施し，断層に沿ってグラーベン(溝)構造があることが明らかになった。震源断層が2重になることは強震動の予測に取り入れる情報として有用だと思われる。, A program was started by the Headquarters for Earthquake Research Promotion Japan in 2002 for the purpose of the reduction of seismic hazard in the metropolitan areas. As a part of this program, deep seismic profiling was begun in order to reveal the regional characterization of metropolitan areas, from 2002 as a five-year project. The final goal of the project is to produce a map of more reliable estimation of strong ground motions in the Kanto and Kinki areas. The surveys required for this project are accurate determinations of a source, a propagation path and a site response for earthquakes. More specifically, purposes of the surveys are to determine the accurate positions and geometry of source faults, subducting plates and mega-thrust faults, crustal structure, seismogenic zone, sedimentary basins, and 3D velocity structures. Reconstructions of source fault and velocity models leads to more realistic 3D estimation of strong motion seismic waves. The surveys were conducted in the fiscal year of 2002-2003, in the Kanto area. Deep seismic profiling was extensively carried out along the 4 lines. In the fiscal year of 2004, the survey area was shifted to the Kinki area. Surveys along two measure lines, Osaka-Suzuka (E-W) and Shingu-Maiduru (N-S) lines were conducted by ERI, Univ. of Tokyo and DPRI, Kyoto Univ. This is a very preliminary report for the Shingu-Maiduru (N-S) line of about 240km, including technical procedure of the survey. In the profile, 13 shots (100-700kg) of dynamite and 3 multivibrator (a few hundreds of sweeps) with 4 vibroseis trucks were used for refraction and wide-angle reflection surveys. More than 2000 seismometer stations were set at intervals of 50-100m all along the line. Clear first arrivals and reflections from the Philippine Sea plate and reflectors in the crust were obtained at almost of the stations. The reflections from the Philippine Sea plate are very clear beneath Kii Peninsula and are still visible under the northern Kinki district at depth of about 50-70km. A reflection survey was also carried out across the Arima-Takatuki Tectonic Line. The survey line is about 30km long and a graben-like structure of the fault was clearly revealed.

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.

本稿は，豪雨時を対象とした表層斜面崩壊のモデリングについて示したものである。斜面の安定性は土層内の水分の消長に大きく依存するため、これを精度よく表現し得るリチャーズ式を導入している。降雨実験により、モデルの適用性を検討した後、無限長斜面を仮定した3層からなる斜面の安定性を、リチャーズ式によって評価される土壌水分の消長を考慮して検討している。この斜面安定性の解析法を木津川上流域のタコラ谷に適用し、実際の豪雨時斜面崩壊箇所との比較検討により、本モデルの適用性が確認された。さらに、透水係数、土層厚、安息角、土粒子密度など、モデル中のパラメータが崩壊発生個数に与える影響について感度分析を行い、斜面安定解析において重要なパラメータを特定している。, A landslide simulation model based on the Richards equation for the ground water flow and with assumptions of soil matrixes comprising three horizontal layers was prepared to simulate rainfall induced shallow landslides. The model is capable to explicitly calculate the change in pore pressure in response to transient rainfall. Infinite slope failure was assumed for the slope stability module. The numerical solution of the unsteady pore-water pressure was experimentally verified by the physical experiment. The model was used to reproduce the landslides occurred in 1973/10/26 at the Takora basin located upstream of Kizu river basin. Comparison of the result of transient rainfall model and steady state model was done by applying both models to simulate the landslide produced by the same rainfall. Performance of the transient response model is better compared to steady state model as the latter highly over-predicted the instability. Sensitivity analyses of some of the model parameter were also done which indicates that depth of the layers, soil angle of repose and soil density have great influence on the stability of the soil domain. Correct representation of their values and their proper spatial distribution are vital to enhance the performance of the model output.

土層中のパイプおよび風化基岩に発達したクラックを通した選択流が斜面安定性に及ぼす影響を検討するため，土層と大孔隙内の水流に関する水理モデルを用いて数値シミュレーションを行なった。数値シミュレーションにおいて，表土層と風化基岩層からなる斜面を想定し，それぞれに水理特性値を与え，土層および風化基岩層に関する浸透流計算を行なった。結果より，斜面表層に降った雨水が選択流路を通して迅速に基岩深部に輸送され，選択流路が風化基岩内部で閉塞している場合は，その閉塞点近傍の圧力水頭値の急激な上昇をもたらすことが確認された。この圧力水頭上昇によって，斜面が不安定化し，斜面崩壊の危険性が高まることが示された。, Numerical experiments were conducted to assess the effect of preferential flow through pipes and cracks within weathered bedrock on slope stability, using hydrological model in which water flows within both the matrix and macropores. The hillslope consists of soil and weathered bedrock layers. Hydraulic properties were assigned to the weathered bedrock as well as the soil layer, and the regolith flow calculations were conducted within the slopes. Results demonstrated that the preferential flow pathway rapidly transported rainwater to the deeper layer of the slope, and if the outlets of the preferential flow pathway remained within the slope, the pressure head increased around these points. This increase in pressure head caused a decrease in the factor of safety at the deeper layer of the slope.

水位観測情報が不足した状況下において地下水流況を把握するため, 水位観測データとそれに相関性のある基盤高のボーリングデータから水位分布をcokriging推定した。すると相互相関係数の変化から, cokrigingの推定システムが基盤高との相互相関性を補助観測データとして活用して分布推定していることが見て取れた。Cokrigingは推定精度の低下を最小限に抑える効用があり, FEMより良好で妥当な推定分布を算出することが分かった。, Several numerical tests in this work are presented to demonstrate the cokriging effects subject to the insufficient data in cokriging estimation of the groundwater levels in space. A groundwater level to be cokriged is evaluated as a linear combination of the available sampling data on groundwater levels and on bed elevations, which are spatially correlated with each other. Cokriging yields reasonable and valid results because it can interpolate less sampling data due to its ability to adequately pick up the available cross-correlative data. The high applicability and reliability of the cokriging method can be reinforced with the above results.

有害物質を含んだ固体系廃棄物を地盤工学的に有効利用する際には, 地盤環境に対する適切な影響評価を行う必要がある。本研究では有効利用を目的とした処理を行った廃棄物に対して複数の溶出試験を実施し, 地盤環境影響要因としての溶出特性, セメント固化による重金属の固定化効果, 溶出操作の相違が溶出特性に与える影響について検討し, 適切な溶出操作について議論を行った。, The leaching characteristics from the stabilized wastes are discussed from the viewpoint of landfilling and geotechnical utilization. Municipal solid waste incinerated fly ash (MSW-ash) and sewage sludge incinerated ash (SS-ash) are used for the experiment. Three different batch leaching test methods and a column leaching test are conducted. The experimental results show that the batch leaching tests could not evaluate the change in leaching characteristics due to the change in pH or the duration to contact with water. Cement stabilization would have a great effect on the immobilization of Cd and little effect on Pb.

大阪湾海成粘土の地盤物性の評価は、今後のベイエリア開発において基本的に重要な課題である。ここでは、海底地盤の物性を鉱物学的視点から解明することを目指し、海底粘土地盤中の粘土鉱物の同定・定量をX線回折分析によって行い、大阪湾海底地盤の水平・垂直方向の粘土鉱物の分布を推定する。それとともに、従来の地盤パラメーターを収蔵している大阪湾海底地盤情報データベースを活用することによって、粘土鉱物組成と地盤物性との相関について広域的に検討し、堆積環境や地域特性について明らかにする。, The objective of this study is to evaluate the relationship between the composition and distribution of clay minerals andphysical and/orengineering properties of seabeddeposits in Osaka basin. Despite of similarity of theirchemical composition, clay minerals show the different physical and/orengineering properties. As the clay minerals are considered to cbfine the engineering characteristics of the clayey soils, special attention was focused on the clay minerals, and identification or quantitative analysis of clay minerals were conducted.Some of them aredependingon the distribution of clay mineral contents.The physical and engineering properties of the soil were obtained by using the Osaka Bay seabed database (SBDB).

This paper overviews the damage to steel beam-to-column welded connections observed in the 1994 U.S. Northridge Earthquake, and this damage was compared with the damage to steel beam-to-column welded connections disclosed in the 1995 Hyogoken-Nanbu Earthquake. Comparison was made from the viewpoints of materials, welding, connections details, and structural systems, and it was emphasized that causes that had brough about the damage differed significantly between the U.S. and Japan and the differences stemed primarily from the design, fabrication, and construction practices characteristic of respective countries.

This paper presents a method is for simulating earthquake ground motions at local-field points under the condition that the recorded motions are specified at several locations and the stochastic characteristics of the field also are designated. The simulated motions at observation points coincide with observed records. The state equation expressing the spatial and temporal field of earthquake ground motion compatible with the modeled stochastic field is derived by using the autoregressive process. A method is developed to identify the unknown coefficient matrices of the autoregressive process from recorded time series of earthquake motions at observation points. The Kalman filtering technique is used to identify the best adaptive estimator of a stochastic field for observations made at discrete spatial and temporal points. This analytical method is very promising for real-time conditional simulation of earthquake motion at unobserved locations.

Under the context of IDNDR, a project entitled "Seismic Risk Assessment of Urban Facilities in A Sedimentary Region Affected by River Route Changes" was conducted by DPRI, Kyoto University and State Laboratory for Disaster Reduction in Civil Engineering, Tongji University, China. The subjects include microzonation of the Shanghai region based on microseism observations. Brief reports were given for microseism observations, geological setting of the Shanghai plain, basic characteristics of microseisms at various soil sites and a reference rock site. To evaluate ground vibrational characteristics, spectral ratios of horizontal components to vertical ones, H/V, were examined. All the H/Vs had sharp peaks, which varied with site location. A linear relation between peak periods of H/V and the depth to bedrock was obtained. Applicability of H/V to microzoning of sedimentary regions was discussed.

A modified Reflection! Transmission Matrices method has been proposed to take into account scattering wave generated on the boundaries between soil layers.The proposed method can determine Reflection/Transmission Matrices without huge mount of CPU time, defining the approximate functional shape of the matrices.The case studies using this method show that the scattered waves exert two effects on the charac-Teristics of the ground response.One is to give other peaks in response function, which can not be represented by one dimensional analysis and the other is to give the similar effect which is caused by the frequency dependent damping.It is also shown that those effects are induced by the characteristics of Reflection/Transmission Matrices.

We tried to use four geophysical prospecting methods (electrical resistivity prospecting method，radar prospecting method，microtremore and elastic wave exploration) for measurements of frozen soils. The result of the survey was that we picked out the electrical resistivity prospecting method better than the other one. Electrical resistivity of frozen soils is inverse proportion to deteriorate of those temperature.

This paper concerns with the applicability of cone penetration tests and measurement of shear wave velocities for assessing the liquefaction resistance of sandy deposits. The miniature cone penetration tests and the measurement of shear wave velocities were carried out before and after the shaking table tests of the silicone oil-saturated horizontal layer under 50-g centrifugal condition. The cone tip resistance (qc) and the shear wave velocity (V) were well correlated to the void ratio of the ground. Judging from the very limited number of experimental results, qc and V could be good indeces of the in-situ liquefaction potential.

RI cone penetrometer tests are carried out at four different sites. The foundation grounds discussed here mainly consist of clayey materials. The measured results by RI cone penetrometers are shown for Kyobashi, Hachirougata, Kurihama and Kinkai Bay site. According to comparison of water content and density profiles by RI cone measurement with the conventional testing results, RI cone penetrometers are proved to be versatile tools for site investigation. Settlement assessment by RI cone penetrometer is also discussed by exemplifying the embankment at Kinkai Bay site. Elasto-viscoplastic finite element analysis correspondingly performed strongly supports the RI cone based assessment. Repeated use of RI cone penetrometer with the advance of construction enables us to assess the consolidation process of the clay foundation.

A Discrete Wavenumber-Finite Element (DW-FE) hybrid method for the problem of SH and P-SV wave inputs was developed. To check the validity of the DW-FE hybrid method, we compared it with a DW and a FE-BE hybrid methods. For the three different impedance ratios and incident angles, transfer functions were calculated. We defined calculation errors for stresses and displacements on the interfaces, and investigated whether the given boundary conditions were satisfied or not. As the results, the DW-FE hybrid method is a powerful tool with which to reduce the calculation cost and time for the seismic response of the ground with irregular interfaces.

Microseisms with period of 1-5 s, observed at Katsuragi-cho, Wakayama Prefecture along a line across the Median Tectonic Line Fault system, exhibit systematic increase of amplitudes in the fracture zone, especially for the vertical and horizontal components parallel to the fault axis (in-plane components), showing the anisotropic amplification effects of fault gauges on seismic waves.Examination of the polarized seismic amplification is important for studying the fault structures as well as the effects of surface geology on seismic waves in the aspect of earthquake engineering.

Underground structures such as buried gas or water pipeline will be heavily damaged if the ground has locally large responses during an earthquake. These lifeline systems that extend for long distances along or below the ground are affected by the seismic response of layered media that have an irregular interface. If an irregular interface exists in a layered media, the ground motion above this interface may be amplified. The effects of surface waves generated from the edge of the interface can not be ignored.We here described the characteristics of seismic ground motion on irregular profile. The method used for simulating ground motion is the three dimensional (3D) discrete wave number method, which was devised to calculate the elastic wave field in a layer-over-half-space media with an irregular interface. Ground strain which affects on the seismic behaviour of underground structures was examined. The 3D wave field was investigated by changing the shape of basin and compared with the results from the 2D analysis.

Using tunnels and shafts in Ikuno mine, which was closed in 1974, we started in 1987 to observe seismic events and temporal change of 1) electric self-potential, 2) apparent resistivity, 3) underground water level, 4) water seepage from tunnel wall and 5) γ ray intensity. The main purpose of our comprehensive observation is to discuss correlation between the observed data in such a stable circumstance as that without excavation, taking account of the continuous observation of crustal movement which have been carried out before the mine was closed. Since all tunnels and shafts below the underground water table filled up with water now, we expect to catch any behavior of rock body in response to any change of underground water and also any preseismic or postseismic effect. From the observation of about five years, we found that the seismic events (S-P time < 0.3 s; M< 0) still occur even now in the vicinity of mine. From our preliminary analysis, the secular change of electric self-potential seems to correlate to the activity of the seismic event in the mine.

This is a survery report, in which the damage to structures done by the 1990 Philippin Earthquake and the intensity of ground shaking during the earthquake are discussed. No strong motion acceletographs were available for areas 100 to 150 kilometers from the epicenter.We therefore calculated the theoretical distribution of maximum accelerations in the region near the earthquake souce. The calculated intensty of gruond motion was compared with the estimated maximum acceleration levels from fallen religious statues in churches. The survey results on heavily damaged bridges especialy failure modes are discussed.The slope filures along the falut extent are also discussed.

Soil amplifications for long-period (1-1Os) microtremors were studied in three areas affected by the 1989 Loma Prieta Earthquake; Peninsula Cities, Santa Clara Valley and Santa Cruz City, California, where strong motion and aftershock records were obtained. Spectral ratios (ground site/rock site) obtained from simultaneous observations were discussed in terms of surface geology and configuration of bedrock. It was shown that long-period microtremor measurement is useful for microzoning an urban area.

Rapid recovery from earthquake damage is an important issue in lifeline earthquake engineering.This study presents effective procedures to optimize post-earth.quake restoration processes of lifeline network systems.In this study, cumulative number of customers connected to supply nodes is used to indicate condition of recovery, and mean time for restoration of overall customers is adopted as a criterion of optimality.First, in order to make all demand nodes connected to supply nodes, the tree structure that covers all the nodes is identified from trunk lines among the original network.Recovery sequencing of damaged components included in the spanning tree is then determined by use of technique of operations research.Next, an easy method to determine optimal division plan of peripheral pipelines is proposed on the basis of the importance and degree of damage of each potential division. By use of this method, average time for restoration can be minimized with a given number of divisions.Some illustrative examples have been shown.

In order to obtain the optimum base shear coefficient of plane frame structures and the stiffness/strength distribution of composed members subjected to the filtered random excitation, a method of optimization of structures which were composed by strong columns and weak beams with bi-linear hysteresis is presented.Equivalent linearization technique is introduced in the elasto-plastic beams of 3- and 5- story structures. Input excitation used in this study is white noise modified by the Kanai-Tajimi filter. Performance index is selected so as to minimize the sum of the second moment of cross section of columns and beams considering the constraints of ductility ratio of beams and fiber stress of column members. Root mean square responses as well as peak responses such as ductility ratio of beam rotation, base shear coefficient, stiffness/strength distribution of each member are theoretically obtained and compared with the results of simulated responses.

We determine the time dependence of apparent velocities and arrival directions of S- andS coda waves obtained from the array observations on the rock site from local earthquakes. Thewaves at the direct S-wave part propagate from the epicenter directions to the site with higherapparent velocities than the medium S wave velocity. On the contrary, those at S coda partcome from various directions with equal or lower apparent velocity and variations of arrivaldirections depends on time. There is a possibility that the waves with lower apparent velocityare mainly constructed by surface waves generated by the scatterers in the crust.

Lifeline systems such as buried gas or water pipelines will be heavily damagedduring an earthquake if the relative displacement between two points on the groundis large. These long underground structures are affected by the profile of thesurface ground. In particular, if an irregular interface exists in the layered media, ground motion above this interface may be amplified. The mean powers of wavesobserved on the points at surface ground are not constant and an assumption of thestationary process does not hold true.We first simulated the surface ground motion of layered media that had anirregular interface by the Discrete Wave Number Method. The mean powers andcross correlations were examined with simulated waveforms, and the shape of theirregular interface was identified.The relative displacements between two observation points were modeled by theuse of spatial correlation and autocorrelation functions by replacing a simple basinwith two sets of layered media.

In order to estimate the displacement of the laterally loaded group piles fromthat of the single pile, interation factor becomes important. In this study, toinvestigate this interaction factor in detail, we dealt with the simplest case, that is, the interaction between two rectangular aluminum piles (pile width: 2 cm, pilelength: 44 cm), and conducted the tests on model piles for which the same lateralload was applying to each pile separately. From the experimental results, it wasfound that the load distribution becomes small as the pile positioned behind sincethe interaction factors between each pile were not equal because of the difference insubgrade reactions in front of two piles.

研究種目:科学研究費補助金(総合研究B), 報告年度:平成7年度, 研究課題番号:07354009

研究種目:科学研究費補助金(総合研究B), 報告年度:平成7年度, 研究課題番号:07354009

A more comprehensive collection of site conditions at various locations where some typeof liquefaction or no liquefaction was used to determine the relationship between liquefactionresistance ratio, standard penetration resistance and effective overburden pressure. Theresults are shown in Fig. 5, and the field value of cyclic stress ratio separating liquefiablefrom non-liquefiable conditions can be determined with acceptable accuracy from Eq. (7).Furthermore, the background of support for these Fig. 5 and Eq. (7) was considered andthe comparisons of author's proposal with previous methods, H. B. Seed (1976) or Iwasaki-Tatsuoka (1978), were made.

A review of field performance of sandy soil deposits during past earthquakes is conducted withemphasis being placed on CPT qc-values and soil gradation. The empirical relationship separatingliquefiable and non-liquefiable conditions is presented in terms of dynamic shear stress ratio, normalized qc1-values, and fines content or mean grain size. The proposed CPT correlations arecompared with those presented by Robertson & Campanella (1985). The proposed CPTcorrelations are also evaluated using field data and laboratory test results from Canada and Japan.

Microtremors were observed at the earthquake-observational points on the ground andthe rock and at several points in the vicinity of the observational points. The peak frequenciesand amplitudes of the spectra of the microtremors vary with the thickness of the depositlayers. However, the peak frequencies of microtremors are not consistent with those ofspectral ratios of S waves between the ground motions and the rock motions. This is partlydue to the difference of the length of time window for computation of spectra. Moreover, the difference of the nature of microtremors with that of earthquake motions should heconsidered in estimating amplification characteristics of ground motions.

In this report, the dynamic response of horizontally layered soil is numerically analyzed, usingthe stress-strain relation of sand and the equation of motion of two phase mixture. The saturatedsoil with water is treated as a two phase mixture. As the pore water and the soil particle is assumedto be incompressible, the effective stress analysis becomes useful. In the case of horizontally lay-ered soil deposit, the lateral deformation is considered to be confined during the earthquakes.Then, in this study, the laterally confined condition is taken into consideration.

The concepts of macro- and micro-zoning and earthquake damage potential are definedin the first part of this paper. Secondly, a practical method of the earthquake response analysisis presented applicable to the analysis of damage potentials for coupled soil and building structures.The method considering the elasto-plastic characteristics of both sub-soils and structures is basedon the modal analysis, use of response spectrum and linearization and iteration techniques. Thedistributions of damage potentials are completed in combination of the types of earthquakes, soilgrounds and structures. The illustrative examples for the typical structures constructed in theOsaka area are finally calculated and discussed.

This paper is concerned with the predicted performance of an offshore airportfill to be built on the bed of soft alluvial clay underlain by very thick strata of ple-istocene clays. Coupled stress-flow analysis using the method of finite elements areperformed, with emphasis on predicting the behaviour of the seawall and the nearbyabutment for the access bridge. Elastoplastic and creep properties of the Quaternaryclays is considered in the analysis procedure in a consistent way, through the im-plementation of a plane-strain elasto-viscoplastic constitutive model. The predictedperformance emphasizes the importance of the long-term consolidation of the pleisto-cene clays, in terms of post-construction deformation, as compared with the behavi-our of the overlying soft alluvial clay that is treated partly with columns of denselycompacted sand (SCP) and more extensively with vertical sand drains (SD). It isshown that the vertical stress tends to concentrate into the SCP-treated region ad-joining the more compressible SD-treated region, and that such stress concentrationaccounts for the peak occurring in the profile of compression of the pleistoceneclays along the axis of the access bridge. It is also shown that the initially over-consolidated pleistocene clays undergo yielding in their upper part, along with thegradual dissipation of excess porewater pressures, and that the front of yielding pro-gresses downwards with time. Such delayed yielding is shown to be predominantwell after the end of construction and is accompanied by the delayed, laterally out-ward deformation of the pleistocene clays. This behaviour of the undersea clays iscontrasted with the behaviour of the crest of the sea wall and the abutment footing, both of which exhibit the inward lateral movements with time, in general accord-ance with the settlement profile of the undersea soils along the axis of the accessbridge.

To estimate chemical weathering rate of granitic rocks, natural waters in a very smallbasin in the Rokko mountains have been collected weekly over a six-year period (1980-1985). The XRD indicates that kaolinite is the main product of plagioclase alteration inthe weathered granitic rocks. The water compositions are plotted in the field of stabilityof kaolinite in a phase diagram for the system Na-SiO2-Al2O3-H2O. This fits the XRDevidence that the main product phase is kaolinite, and it indicates that solution/kaoliniteequilibrium may play a role in controlling the water compositions. The amount of kaoliniteproduced by CO2-bearing water reacting with granitic rocks is estimated as 35.1 g/m2/year, and the total amount of weathering rocks is estimated as 55.3 g/m2/year.

Linear and nonlinear seismic response analyses were performed for the water-soil-revetmentstructureinteraction system so as to investigate the effect of hydrodynamic pressure on the responseof the structure and back-filling soil by the finite element method.Structural responses such as acceleration, velocity and displacement were not affected verymuch by hydrodynamic pressure. In general, the existence of water caused higher stability ofthe structure and less yielding of soil, hydrodynamic pressure, however, yielded large overturningmoment and low safety factor against sliding of the structure compared with those in the case ofwithout water when the system was subjected to strong ground motion.

To date, numerom researches have been pursued on the liquefaction of saturated loose sand inconnection with the investigation of the possible disastrous effects of earthquakes upon soft ground.In this report, the author attempts to devote a discussion on the following items: (1) liquefactionof quick soils, e.g. quick clay and true quick sand, (2) liquefaction of saturated sand due to cyclicloading and (3) evaluation of liquefaction potential of a deposit. It is further attempted to esti-mate the liquefaction potential at Osaka area for some design earthquake, and the results areshown in Fig. 8.

This research aims at the study of the occurrence of runoff phenomena and its characteristicsthrough the dynamic (in terms of time and space) behaviors of soil water flow in the mountainouswatershed.In this paper, the study of the runoff problems was carried out, mainly using the various soilmoisture suction data of sub-surface soil water observed at 3 points in a study watershed.After some careful examinations and study of these data, the results are summarized as follows.1) On the dynamic behaviors of soil water in the surface layer, there is a great difference betweenthe surface soil on the foot slope close by the mountain stream and the other points.2) It seems that when the surface soil of the slope is dry or in the initial stage of runoff, the wet soilof the slope in the proximity of a stream or the stream itself contribute considerably to the areaproducing runoff.It is infered that the area producing runoff expands in the direction of the slope as rainingprolonged.3) The results of this observation made in the study watershed proved the propriety of the model of"Partial Area Concept".4) In this watershed the flow in the surface layer can be divided into sub-surface flow and laminarsurface flow, by border of about 7 mm of storage depth.5) The parameters P and K in the storage function equation (1) are closely related to the behaviorsof the flow on the surface layer and the average scale of the area producing runoff for each occurrence.

The mechanical behavior of a rock mass with clayey seams was investigated by conducting aseries of triaxial compression tests. In the tests, a rock mass was modeled by a specimen made bysandwiching an alluvial clay seam between two pieces of Ohya stone. From the experimentalresults, it has been found that even if the thickness of the clayey seam is so thin, the shearstrength of a rock mass is almost governed by that of the clayey seam.

Vibrations of a massless rectangular foundation on a viscoelastic multi-layered medium areinvestigated for the cases where the vertical, horizontal or rotational exciting force is acting onthe foundation. The dynamic characteristics of such foundation-ground system are representedas the form of "Dynamical Ground Compliance" which means the complex transfer functionbetween the foundation displacement and the exciting force. Some numerical examples areshown in graphical form for the three kinds of typical ground models and a model based on thedata for an actual soft ground. The effects of surface waves, wave diffusions and dissipations, resonance phenomena and parameters defining the coupled system are examined.

The paper deals with the seismic response analysis of near surface ground and structuralfoundation which are subjected to surface waves such as Love and Rayleigh waves. Thefinite element method is applied to the problem, in which the semi-infinite element is firstintroduced to take into account the exact mode shape in the deep base layer.The frequency response function of the foundation structure and that of near surfaceground are computed for the incidence of the fundamental mode of Love and Rayleighwave. The result of numerical computation shows that the foundation structures submergedin the surface ground has a shielding effect of surface waves of higher frequency componentfor the response of near surface ground behind the structure.

The paper describes the results of investigation on the bearing capacity of foundation and thefailure pattern of ground with an inclined surface. Theoretical approaches are compared witheach other based on the theory of rigid-plasticity. A series of experimental study is also performedby dense sand-models in order to observe the failure mechanism of ground under such a condition.It is concluded from the test results that the failure pattern of ground with an inclined surfacecan be explained by applying the theory of rigid-plasticity.

A flexible structure embedded in a viscoelastic multi-layered medium over a rigid half-spaceis considered when subjected to horizontal, harmonic, base rock motions or exciting forces actingat the top of the structure. The method of the dynamic response analysis for the system is de-scribed on the bases of the expansion technique of eigen functions and the variational method. As-suming that the system is two-dimensional, the analysis is made for the two cases in which SH-waves (or the Love waves) and P- and SV-waves (or the Rayleigh waves) are caused respectively.To give the validity of the method of analysis some numerical examples are shown.

Weathering conditions on the mountain slopes in Obara Village, Aichi Prefecture was classifiedinto eight types according to the ground-surface examination and the seismic prospecting of P-wave.More detailed survey of the landslide scars which belong to different weathering types was carriedout to estimate the underground structure of the slopes. It was revealed that the slip surface of thelandslides dominantly occur in the weathring zones calssified as Aw-1 and Aw-2.

In this study, proposed are the two methods of classifying the dynamic resistant force ofthe structural foundation and surface layer system into hysteretic restoring force related tothe response displacement and damping force related to the response velocity.The experimental results are investigated through the two methods to find that the rela-tion between the velocity and the damping force is nonlinear; I.e., the rate of increase inthe damping force decreases for increasing velocity. The degree of the nonlinearity becomesremarkable when the excitation frequency is lower than the natural frequency of the sur -face layer. This tendency can be reasonably explained from the energy dissipation due topropagation waves away from the structure.