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| 1.
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高橋, 直人 ; 田崎, 和江 ; Takahashi, Naoto ; Tazaki, Kazue
概要:
金沢大学理工研究域地球社会基盤学系<br />金沢大学角間2号井戸(深度150m,取水区間深度62〜73m,同78.5〜95m,同106〜138m)では,これまで地下水位・地下水温・電気伝導度の自動観測を行っており, 2007年3月25日に
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発生した能登半島地震前後における10分間隔の詳細な経時変動データを取得することができた.地下水位は,揚水ポンプの停止時に深度31m,稼動時には深度39m程度の値を示した.電気伝導度は,ポンプの停止時に18.2mS/m,稼動時には18.7mS/mの値を示した.季節変動として,夏〜秋にわずかに高く,冬〜春にかけて低くなる現象が見られている.地下水位および電気伝導度については,地震の前後で異常な水位変動は見られなかった.地下水温は,地震時直近のポンプの停止時に12.3℃,稼動時に12.6℃の値を示した.通常地下水温は夏に低く,冬に高い傾向が見られているが,能登半島地震の前約2週間の間,地下水温が約0.5℃高い傾向が継続する現象が見られた.この傾向はポンプの稼動・停止や,気温,通年の季節変動傾向などとは異なるパターンの変動であった.今後は,より震央に近い地域における地下水位・水温・水質の観測記録との照合や,余震にともなう変化の観察などの再検証が必要であるものと考える.<br />The effect on groundwater in Kakuma-No.2-well at Kanazawa University by the Noto Hanto Earthquake struck at 9:41 a.m. 25th March 2007, reported in this study. The groundwater level indicated 39m in depth during operation, whereas the level indicated 31m in depth without operation. The electric conductivity (EC) of the groundwater during operation showed 18.7mS/m, whereas the EC showed 18.2mS/m without operation, using automatic measurement system. The EC tend to be higher in summer-autumn than that of winter-spring, which had not changed the value before and after the earthquake. On the other hand, the groundwater temperature showed 12.6℃ during operation whereas the temperature showed 12.3℃ without operation. The temperature clearly increased 0.5℃ for 2 weeks before the earthquake, and decreased the temperature after the earthquake. The results suggest that the earthquake gave the effect on the groundwater temperature as well. We need comparison with the record collected from the nearest area of epicenter in our future work.
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| 2.
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一井, 康二 ; 秦, 吉弥 ; 村田, 晶
概要:
道路盛土の耐震性評価のためには，盛土のある各地点における地震動を適切に設定する必要がある．今日までに様々な地震動設定手法が提案されていることを踏まえると，盛土の耐震性評価に適した地震動の設定手法を議論しておくことは有用である．そこで本稿では
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，委員会活動の一環として，地震工学の研究者・技術者を対象にアンケート調査を実施した結果について報告する．アンケートの内容は，種々の地震動設定手法の長所・短所についての技術者の認識の実態と，著者らが提案している常時微動計測結果により線状構造物である道路盛土をゾーニングする方法を実務に適用する際の課題である． The method to determine the input strong ground motion is a key factor in the seismic performance assessment of road embankments. However, the procedure to choose the method is dependent on the experience and capability of the engineers. In this study, a questionnaire survey to 83 researchers and engineers of the earthquake engineering field in Japan is conducted to reveal their recognition on the features for various earthquake motion determination method. The procedure to conduct microtremor measurement for input strong motion determination and zoning judgement based on H/V spectrum obtained by microtremor measurements are also investigated. The results of the questionnaire are useful for a reference in practical earthquake motion determination for road embankments.
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高橋, 雅憲 ; 高山, 純一 ; 中山, 晶一朗
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平成１９年３月に能登半島地震が発生し，交通の大動脈である能登有料道路のほか，多くの幹線道路が被災した．そのため直後から道路交通に混乱が生じ，あらゆる社会経済活動に影響を及ぼした．その結果，地震などの災害発生時には，混乱を避けるために地域住民
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，特にドライバーに対する道路交通情報の提供方法が重要であることが改めて認識された． そこで本研究は，災害時におけるよりサービスレベルの高い道路交通情報の提供を目指し，地域住民にアンケートを行い，地震時の道路利用状況及び情報取得状況を調査する．そして今回の道路交通情報提供方法は適切であったかを分析し，また今後どのように提供すべきか検討することを目的とする．Noto Peninsula earthquake occurred in Ishikawa Pref., in March, 2007, and the Noto Yuryo, and many arterial roads were damaged. This led to the conosiderable confusion of the road traffic in Noto Peninsula area and gave the influence on all kinds of social/economic activities. Therefore, an method of providing the traffic information for drivers is important in the case of disasters such as earthquakes. We carried out a questionnaire survey for local inhabitants and investigated the road use situation at the time of the Noto Peninsula earthquake and the information acquisition situation about it. We also analyzed whether or not the method of providing the traffic information was appropriate. In addition, we examined the best traffic information in the case of earthquakes.
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Takahara, Toshiyuki ; Sugimoto, T. ; Sanada, H.
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The Levees of Shinano River were subjected to many damages at Niigata Chuetsu Earthquake in 2004 as well as Tohoku-Pacific Ocean Earthquake in 2011. The damage of levees depends not only on the distance from the epicenter, but also
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on the soil profile of levee and its foundation. In this study, we classified the damage of levee into five types, and investigated the relationship the geological categorization and the seismic characteristics of the levee with the damage types. The natural frequency for multiple layers and the shape of transfer function were adopted as the seismic index, because the natural frequency can be express the seismic stiffness of levee. To obtain natural frequency of multiple layers, we carried out the linear elastic analysis based on multiple reflection theory using the results of standard penetration and laboratory soil tests. Those investigations of levee have already performed at each 1 km, for every main rivers managed by MLIT, therefore the new investigations are not required. However, the interval of 1 km is not enough for management length in Japan sea side region, because of its geological complexity compared with the Pacific Ocean side. To specify the representative levee length for one borehole logging, the geomorphologic data was considered. To estimate the damage rank, the influences of magnitude of ground motion should be considered. In this study, the multiple linear regression analysis, which the base acceleration, the natural frequency and the shape index of transfer function were adopted as dependent variables, and its explaining variable was damage rank, was performed to prediction of damage rank.
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吉田, 雅穂 ; 宮島, 昌克 ; 北浦, 勝
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金沢大学理工研究域環境デザイン学系<br />Horizontal ground displacements caused by liquefied ground flow were observed at reclaimed lands
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during the 1995 Hyogoken-Nambu earthquake. Many displacements were not due to the influence of the inclination of ground surface and movement of quay wall. The present paper aims to find the causes of the displacements mentioned above and to investigate how to estimate their directions and magnitudes. A method is proposed here to evaluate the spatial distribution of SPT N-value. Although this method is usually used to investigate a trend surface on altitude, it was applied to evaluation of the spatial hardness of soil layers. The gradient and azimuth of trend surface on SPT N-value were found using data of reclaimed lands in Kobe area. The boundary of geological stratum that was decided by the distribution of SPT N-value was easily estimated using the proposed method. Furthermore, it was clarified that the direction of horizontal displacement of ground surface was influenced by the inclination of boundary between soft and hard soil layers. It will be expected that this method is useful to estimate the liquefied ground at the level reclaimed land.
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Kitaura, Masaru ; Miyajima, Masakatsu ; 北浦, 勝 ; 宮島, 昌克
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金沢大学理工研究域地球社会基盤学系<br />Earthquake damage to water supply pipelines during the 1995 Hyogoken-Nambu earthquake was investi
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gated. An overview of the damage to water supply pipelines in the Hanshin area is presented and the relationship between the damage to water supply pipelines in Kobe city, geological features and damage to buildings is discussed. The damage is compared with that which occurred from past earthquakes. The study lead to the following conclusions. (1) The majority of failures occurred in pipelines of relatively small diameter. (2) The damage rates for asbestos cement pipe and vinyl pipe were high. The replacement of old pipe such as asbestos cement pipe is urgently required. (3) Joint separations were extensive. Joint separations for cast iron pipe occurred in the older lead and mechanical joints. (4) Liquefaction caused extensive damage to pipelines. The ductile cast iron pipelines with earthquake-proof joint did not suffer damage even in the liquefied area. The effect of earthquake proof joint was confirmed. (5) Since damage to the pipe fittings such as valves, hydrants, etc., was extensive, the strength of the pipe fittings should be improved.
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宮島, 昌克 ; 伊藤, 真美 ; 川畑, 公義 ; 北浦, 勝 ; Miyajima, Masakatsu
概要:
金沢大学理工研究域地球社会基盤学系<br />阪神・淡路大震災以降、地震後の機能性能に着目した耐震設計について検討されてきており、ライフラインについてもその例外ではない。本研究では、上水道管路に注目し、地震後に要求される機能性能について整理
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するために、水道事業体へ向けてアンケートを実施するとともに、機能性能の1つの評価指標として困窮度を定義し、機能性能を考慮した耐震補強法について考察し、金沢市の上水道システムにおけるケーススタディを行った。
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| 8.
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吉田, 雅穂 ; 宮島, 昌克 ; 北浦, 勝 ; Miyajima, Masakatsu
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金沢大学理工研究域地球社会基盤学系<br />本研究は, 地表面がほぼ水平な地盤において発生する, 液状化地盤の流動メカニズムを明らかにするものである.1995年兵庫県南部地震の際に六甲アイランドで生じた地表の水平変位の方向性について, そ
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の分布特性や発生要因を検討した結果, 地表面傾斜や護岸移動の影響をあまり受けていない地盤において, 南方向の水平変位が卓越していたことを明らかにし, この方向と当該地盤の土層境界面の傾斜方向とが一致していることを示した.また, 地表面が水平で基盤に傾斜を有する地盤をモデル化した液状化実験を実施した結果から, 基盤傾斜の方向に地表水平変位が発生したことを示した.
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| 9.
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芹川, 由布子 ; 吉田, 雅穂 ; 宮島, 昌克 ; Serikawa, Yuko ; Yoshida, Masahiro ; Miyajima, Masakatsu
概要:
金沢大学理工研究域地球社会基盤学系<br />2011年東日本大震災では埋立地等の戸建住宅に液状化被害が多発し，その数は計2万7千棟を数える．これらの被害を受け，地震による液状化被害は深刻な問題となり，今後の安全な宅地供給を期待するとともに
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，液状化対策コストの低廉化を進めることが求められている．著者らは，間伐丸太を液状化対策に利用することを提案しており，より実用的な工法の考案に繋げるため，戸建住宅を対象とした液状化対策工法の需要と費用対効果を明らかにするための一般市民を対象としたアンケート調査を行った．また，既設構造物の液状化対策工法として構造物周辺地盤に丸太を打設する工法に着目した．浦安市で提案された格子状改良工法を比較対象として，構造物周辺地盤に丸太を打設する方法の有効性について模型振動実験による検討を行った．<br />During the 2011 Great East Japan Earthquake in Japan, extreme liquefaction caused extensive damage to residential houses in the Kanto Plain region and resulted settlements and tilts larger than that was observed during the past earthquakes. This paper deals with a proposal of ground improvement technique by installing logs into loose sand layer as a soil liquefaction countermeasure for existing residential houses. First, a demand for countermeasure of residential houses and reasonable cost of construction were shown by questionnaire surveys . Next, small-scale shaking table tests were carried out to propose how to apply the technique of log pilling around existing residential house. As a result, the magnitude of settlements of the house which was improved by log piling with an inclination and the fixed top of logs became quite small.
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橋本, 隆雄 ; 宮島, 昌克 ; 池本 , 敏和 ; 酒井, 久和 ; Hashimoto, Takao ; Miyajima, Masakatsu ; Ikemoto, Toshikazu ; Sakai, Hisakazu
概要:
金沢大学理工研究域地球社会基盤学系<br />日本には，城壁，宅地，鉄道，道路等の伝統的な石積擁壁が膨大な数存在し，これまで地震の度に大きな被害を受けている．しかし，1995年の兵庫県南部地震以降，様々な構造物の耐震補強が進む中，地震時にお
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ける石積擁壁の崩壊のメカニズムが不明であるため，耐震補強などの対策が未着手な状態にある．したがって，石積擁壁の地震時における崩壊のメカニズムを解明し，適正な耐震補強対策を適切に施す基準を作ることが急務とされている．そこで本論文では，擁壁の模型実験及び不連続変形法（DDA）を用いて崩壊メカニズムの解明を行った．<br />Since collapse mechanisms of masonry retaining wall caused by earthquakes have been less well understood, there are no guidelines of aseismic design for that structure. To assess aseismic performance of masonry retaining wall, we should collect more data via both shaking model tests and numerical simulations. In this study, we conducted a series of shaking test with 1/6 scaled model and DDA (Discontinuous deformation Analysis) simulations to validate the accuracy of our simulation code. The results of comparisons revealed that the residual patterns of displacement in the DDA simulations are in good agreement with those measured in the shaking table tests. Additionally, the DDA simulation approximately predicts the starting point and the beginning time of collapse inside the retaining wall. Through these discussions, we have confirmed that the DDA is a powerful tool and is complementally applicable to considerations in seismic design of masonry retaining walls.
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