Damage to Water Supply System and Surface Rupture Due to Fault Movement during the 1999 Ji-Ji Earthquake in Taiwan

On September 21, 1999, a large earthquake of magnitude 7.3 (CWB) occurred in Taiwan resulting in a death toll of over 2,000 people. It was also reported that more than 12,000 buildings and houses were damaged and about the half of those totally collapsed. The present paper concerns with the damage to water supply system and surface rupture during the 1999 Ji-Ji earthquake in Taiwan. An outline of the water supply system and damage to it is presented. The relationships between the damage to water supply pipelines, pipe material, pipe diameter, etc. were investigated. Lifeline system such as electricity, water supply and gas also suffered severe damage. Survey of the surface rupture and damage evaluation of buildings was also conducted

Damage by the 2011 Great East Japan earthquake

The Tenth International Symposium on Mitigation of Geo-disasters in Asia Matsue Symposium Place: Shimane Civil Center, Matsue Date: 8 October 201

Liquefaction Countermeasure Technique by Using Logs for Carbon Storage Against Global Warming

Global warming is one of the most serious problems which faced by civil engineers in this century. Because a wood can store carbon within itself, the utilization of wood in the construction projects may contribute to the mitigation of global warming. The technique of ground improvement by installing logs into loose sand layer as a countermeasure against soil liquefaction was proposed in this study. The logs had been used as pile foundation until 1950\u27s in Japan. However, as the wood has high possibility of a decrease in strength by decay, the utilization of wood become minority in the construction projects. First, since a lot of former wooden piles were found at the riverbed of the Asuwa River in Japan in 2005, the soundness of wood was evaluated. From the test results, it was confirmed that the level of decay was extremely low and the compression strength exceeded the allowable stress of wood pile, though they were buried under the riverbed for 59 years. Second, small scale shaking table tests in a 1-g gravity field were carried out using a composite ground which was made of loose saturated sand layer and the improved ground by piling with logs. It was clarified that the logs installed in liquefiable soil layer could increase the resistance of ground against liquefaction and decrease the settlement of structure

既存の強震計に装着できる地盤破壊検知センサーの開発

金沢大学工学部研究助成期間に2001年芸予地震や2003年三陸南沖地震、宮城県北部地震、十勝沖地震が発生し、液状化地盤の近傍で強震記録が得られたことから、それらを用いて液状化センサーの検証を行い、検知精度を確認するとともに残された問題点を明らかにすることができた。すなわち、これまでに本手法確立のために用いてきた液状化地盤の記録の多くが、上下動成分の卓越した1995年兵庫県南部地震のものであったので、海洋型地震である十勝沖地震にも適用するために指標の閾値を再検討する必要性を明らかにした。これらの地震において、強震計の設置場所によっては、設置箇所の微地形の影響や周辺建物の振動の影響が強震記録に反映されることが議論に上ったので、その点についても検討を始めた。すなわち、十勝沖地震の際に大きな強震記録の得られた地点において、設置状現や地表面地盤特性を調査し、それらの影響について検討した。さらに、強震計の設置状況を把握するために石川県内のすべての強震計設置位置を調査し、設置状況、設置場所の表層地盤特性などのデータ・ベースを構築した。さらに、1999年台湾・集集地震に見られた断層運動に伴う地表面変位の検知に関しても研究を行った。これについては、従来の液状化センサーとは異なった検知指標を提案し、台湾・集集地震で得られた強震記線を用いて検証を行った。逆断層の近傍で得られた強震記録が台湾・集集地震に限られたので、さらに多くの強震記録を発掘し、精度の検証を行う必要がある。The present study is focusing on detection of liquefaction and large ground displacement induced by fault movement. First, amplitude characteristics of strong ground motion records were investigated. Time histories of ratio of vertical ground acceleration to the horizontal one was calculated from ground acceleration records at ground surface. Next, frequency characteristics of the ground acceleration records were studied. The average predominant period of the strong motion was calculated here. Then these indices were verified by using more than one hundred acceleration records at ground surface including the 2001 Geiyo, the 2003 Sanriku-minami, the 2003 Miyagiken-hokubu and the 2003 Tokachi-oki Earthquakes in Japan.The velocity of strong ground motion obtained by integration of acceleration is used for a new index to detect a large ground displacement induced by fault movement. The records of the 1999 Chi-Chi earthquake, Taiwan, verify this new index. As a result, the new index using the velocity wave form obtained from strong ground motion records within few kilometers from fault rupture identifies occurrence of a large ground displacement induced by fault movement.研究課題/領域番号:13555129, 研究期間(年度):2001-2003出典：「既存の強震計に装着できる地盤破壊検知センサーの開発」研究成果報告書　課題番号13555129 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）)　　　本文データは著者版報告書より作