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The quantification of the seismic past of regions during non-instrumental period is important for seismic design and disaster mitigation. The utilization of damage to speleothems of caves as one of tools of paleo-seismology has been recently receiving a particular attention. However, there is no such a study in Japan so far. This study is first attempt by the authors to study on the possibility of the utilization of damage to speleothems of caves for quantifying past earthquakes. The authors investigated the cave of Ishigaki Island and Nakabari cave of Miyako Island in relation to the 1771 Meiwa earthquake, which was estimated to had occurred on a fault between Ishigaki and Miyako Islands. The traces of the damage to speleothems were found in the caves. Some of traces observed can be directly associated with the 1771 event while the rest may indicate much earlier large seismic events. There is no doubt that the utilization of damage to speleothems of caves is an important tool for the quantification of the seismic past. However, one must pay great attentions on the other possible causes of damage due to non-seismic origin. Since similar damage to speleothems could exist in caves in other seismically active parts of Japan, the authors have been considering to extend this study to caves in such areas., 耐震設計および防災対策上,地域の過去における(特に非計測期)地震活動の定量化は重要である. 近年考古地震学において利用されている手法の中で鍾乳洞における石筍やツララ石の損傷を基にする手法が着目をされるようになってきている. 現段階で, 日本でこのような手法を用いて行った研究例は見当たらない. 本研究では, 鍾乳洞の石筍やツララ石の損傷を基にする手法を用いて, 日本で過去の地震活動を定量化するための初めての試みである. 著者らは1771年に石垣島と宮古島の間の海域で発生したと予想されている明和地震との関連で石垣島鍾乳洞と宮古島の中原鍾乳洞を調査した. 両鍾乳洞の調査では石筍やツララ石が損傷を受けていることが明確になった. その損傷の一部は, 直接1771年の地震と関連し, それと別な損傷は過去に発生した大地震によるものと判断された. 日本における石筍やツララ石の損傷を基にする手法は有効的な手法であることは間違いないが, 地震以外に発生し得る損傷要因についても十分な配慮が必要である. 地震活動が他の日本の活発な地域でも同様な現象は存在し得るので, 著者らは本研究をそれらの地域にも発展させることを考えている.

制度:新 ; 報告番号:乙2313号 ; 学位の種類:博士(工学) ; 授与年月日:2011/2/25 ; 早大学位記番号:新5655

平成9年度～平成10年度科学研究費補助金(基盤研究(B)(2))研究成果報告書, 研究概要：沖縄における台風災害対策に資する基礎的研究を推進することが,本研究の主たる目的である.沖縄は,我国唯一の亜熱帯地域であることから,外の地域と比較して極めて特異な地域特性を有している.特に,自然の異常現象の観点からみれば,極めて大型で強い台風の常襲地帯であり,近年に入っても極めて大型の台風が沖縄地域に来襲しており,沖縄は外の地域とは相当異なる自然災害を受けてきている.この状況を踏まえて,所謂亜熱帯型自然災害対策に資する基礎的研究の推進が強く要望されている.そこでこのような社会的ニ-ズに的確に対応するために,平成1年度科学研究費重点領域研究「亜熱帯地方・沖縄における都市災害の特性評価とその防災力の変遷について」では,沖縄県における台風災害に関する資料を収集し,データベース化を行い,更に,その台風災害データベースシステムを活用して,沖縄に来襲した台風の経路,規模及び頻度と災害事象の比較を通して,沖縄における台風による都市災害の特性評価とその防災力の時代的変遷の調査分析を行った.そこで本研究では,本台風災害データベースシステムに平成10年度までの台風に関する気象及び災害資料を新たに収集し,台風災害データベースシステムの再構築を行った.また,沖縄県は広域にわたっているため,地域特性は多種多様であり,その地域特性に応じた災害特性を把握するために沖縄県を6つの地域(気象台観測地点に対応)に分け,市町村別災害資料を新たに収集し,それぞれの地域について台風に関する気象デ-タ(最大風速,最大瞬間風速,降水量)と施設災害(家屋全壊,床上浸水,道路被害,港湾被害,停電等)の相関関係について詳細に調査分析を行った., 要約(欧文)：The ryukyu islands are located in the oceanic subtropical climate with the continuous threatening of typhoons. Tropical Typhoons frequently pass near the Okinawa islands and influence various branches of the society. To prevent and alleviate disaster on the typhoon, it is necessary to grasp of characteristics of tropical typhoons and take preventive measures. Also it is of necessity to promote enforcement of the vulnerability of the disaster-prone areas. A typhoon disaster data base system in Okinawa has been constructed in this study. The typhoon disaster data base system is composed of a database of the weather extreme-values due to typhoons, the typhoon routes, the typhoon disasters and the restoration works and a sub-system to perform the management. The management system is composed of the programs to execute input, rectification, deletion, search and output of the data. On the other hand, the characteristics of the typhoon disasters have been investigated using the typhoon disaster data base system.

平成元年度科学研究費補助金(重点領域研究(2))研究成果報告書, 研究概要:（平成元年度時点）本研究は、これまでに沖縄に来襲した台風の経路、規模及び頻度と都市宅地災害事象及び海岸地形変遷の比較を通して、亜熱帯地方・沖縄における台風による都市災害の特性評価とその防災力の変遷を考究することを目的とするものである。まず、沖縄に現在する台風に関する資料情報は、各機関に散在しているため、逸散したり、廃棄される可能性もある故、早急に収集し、データベース化を行った。本台風災害データベースシステムは、台風極値(最低気圧、最大風速等の極値)、台風経路(北緯、東経)、台風災害(死者数、床上浸水、被害金額等)、及び台風災害復旧工事(種別、施行位置、工事費等)の4つのデータベースと、台風経路を表示するプログラムから構成されている。本台風災害データベースでは、対話式によって、必要とするデータを瞬時に検索することができ、データを必要な形式に並びかえることができる。次に、地方の都市化を評価する主指標の一つである宅地スプロール化に着目し、沖縄における最も都市化の顕著な那覇市における都市化と地勢的特性を径年分析し、その結果と上記災害データベースによる災害資料を比較検討することにより、都市防災力の変遷を考究した。又、沖縄の海岸地形、特にリーフ内面積の径年変化と海域変化と海域災害資料と比較し、その相関関係を検討した。本研究により得られた結果の主なものは;(1)宅地スプロールの変遷に伴う宅地災害発生条件の変化の対応関係が明らかとなった。事例の素因・誘因分析により、災害発生条件は、限界傾斜角と湧水系、地滑り表土種と地形で評価され得ること;(2)沖縄の海岸のようにリーフを有する海岸は、波浪に対して自然の防災力を有し、リーフの海岸線に対する沖方向への距離、即ちリーフ内面積が海岸の防災力評価に対する一般性のある予測指標となることが明らかになったこと、等である。

With the application of high-speed electronic computers, the matrix methods have become prominent means for analyzing complex engineering structures and the advantages of the matrix methods have been shown in many cases. While the techniques of the matrix methods are simple and straight forwards, a problem of large matrix orders becomes apparent in general caces, which results in the need for large storage facilities in a computer. Also the round-off error and the excessive computation time make the methods less applicable. Generally, many engineering structures are arranged in uniform (i. e., beams on equidistant supports, cables with equal spaces.) For such structures, the discrete field analysis gives more advantages and it will be shown that this method is superior to the matrix methods. This is the direct application of finite difference calculus and the mathematical models are difference equations. Exact closed form field solution can be found for many regular cases and such solutions are valid over entire structures. Therefore, the solutions are essentially independent of the size of structures, that is, the same solution form holds for the structure with a very small or a very large number of nodes or elements. For more complex structures with irregular patterns, this method also can be applied. A closed form solutions are not to be found easily for these cases. However, the numerical technique called as 〝walk through" gives solutions, which is out of presentation of this paper. This paper presents the application of the discrete field analysis using simple examples such as continuous beams and cable nets. The closed form solutions are obtained, which are in the forms of single and double finite Fourier series. While the same examples are analyzed by the first author using the variational technique(⁵), this paper presents the direct application of the force equilibrium on node points. It will be noticed that same difference equations are obtained. The validity of this technique can be proven theoretically by the general concept of the variational technique. Comparing with the variational technique, this method yields simple forms. This paper emphasizes on the numerical calculations, which were not presented in the previous paper(⁵)., 紀要論文

This paper presents a result of preliminary study on landscape characteristics along the highways on the east coast of eastern part of Okinawa island. Presented is the second part of the study under the same title. Methology and the factors discussed are alrnost the same as before., 紀要論文

National highways in Okinawa prefecture were under control of the U. S. Army before the reversion of Okinawa to Japan. However, the materials of the highways were not transfered properly, which yielded the difficulties in evaluating the bridges referring to the present specification. Recently significant deterioration of reinforced concrete bridges has been observed and the necessity of the evaluation becomes urgent. This research intends to investigate structural and meterial problems involved in the deteriorated reinforced concrete bridges, where four bridges; Igei, Yaka, Kaneku and Ichinichi, were taken as consideration. Static and Dynamic tests were conducted and the results are compared with the theoretical ones calculated by the methods of Guyon-Massonnet and Homberg. This paper investigates mainly the static behaviors where the emphasis is placed on the load capacity of the bridges. Also, the impact coefficients are obtained from the tests, with which problems in dynamic behaviors are investigated., 紀要論文

In planning of underground structures stability analysis of rock masses requires precise properties of fractured rocks.\nIn this paper, an experimental study of rock-like materials by uniaxial compression tests is presented using a new type of high stiff loading machine. Four kinds of rocks were selected, namely, Oya-stone (green tuff), Kobe-tuff, cement mortar and marble stone. Three differrent loading procedures were employed, i.e., static loading, incrementally cyclic loading and cyclic loading in post-failure region (see Fig. 4).\nThe machine used in these experiments has high stiffness about 312 ton/mm, and is capable of controlling either deformation or load of the specimen by mechanical action of the wedges under steel blocks installed in parallel with a specimen. This loading machine is very practical and efficient to obtain complete stress-strain curve of geologic materials.\nMain results are summarized as follows:\n(1) Obtained stress-strain curves are resolved into four characteristic regions due to the progress of fracturing, namely, intact, crack, fracture, and flow regions. The strains corresponding to each region are related to the strength, or the fablic of materials.\n(2) Tests of incrementally cyclic loading show that the envelop of unloading and reloading curve is coincident with the statical loading curve.\n(3) Relationship between plastic strain and total strain on incrementally cyclic loading are distributed by Weibull's probability.\n(4) Fatigue life under cyclic loading in post-failure region are influenced significantly by crypto-damage due to initial loading and applied stress level., 紀要論文

This paper presents the experimental and theoretical studies on deformation and failure behaviours of the typical weak and hard rocks for conventional triaxial tests under monotone and "weakly" cyclic loadings. These materials show the dilation characteristics at lower confining pressures and the brittle-ductile transition. We present a non-associated plasticity theory using a dilatancy function for plastic behaviour under monotone loading, and an extended multi-response theory to elasto-plastic behaviour under "weakly" cyclic loading. In these approaches, we treat only the strain hardening response of geomaterials as the material behaviour and do not apply them to the strain-softening response since the softening is a structural phenomenon rather than a material characteristic. We present the response functions by a Laplace trasformation. The response models are applied to simulate the behaviours of Oya-tuff under monotone loading with non-linear plastic response, and the behaviours of Funyu-tuff and granite under cyclic loading with non-linear elastic and plastic responses, respectively. We also describe a procedure for conventional triaxial tests of rock materials by a stiff testing machine, a closed measurement-analysis-system for a laboratory test performed by a microcomputer and a data banking system of rock triaxial tests.

Continuous beams are common structural systems in Civil Engineering and are considered to be important since many structural systems admit of the idealization as a continuous beam on elastic supports. There exist various analyses for the system being used conventionally for design purposes. However, this paper intends to propose more rational techniques where finite difference calculus is applied directly. The mathematical model forms a set of difference equations for which closed form or numerical solutions are obtained for several illustrative examples. Field analysis of continuous beams with rotational restraints and non-displacement on the supports has been presented by the same authors. This is the extension of the previous work to apply for more general cases. The numerical technique called as the walk-through method is illustrated for an example and the general technique of the method is presented in the following appendix. The main purpose of this paper is to introduce finite discrete techniques in the structural analysis and the techniques are verified by comparing the numerical results of the two different methods., 紀要論文

According to one of the authors the basic factors of highway landscape can be classified into five factors, that is, botany, geology, hydro-system, urban development and civil engineering structures. In tnis paper the authors, recognizing bridge as one of the most important landscape strurctural factors, have disccussed some fundamental aspect in its evaluation in landscape together with the presentation of surveyed results of the bridge conditions in Okinawa Island., 紀要論文