Takeo Umezaki

Dynamic Ring Shear Characteristics of Artificially Cemented Sand

In recent earthquakes, lots of landslides occurred in natural slopes composed of weakly cemented and during or immediately after earthquake. The slope failure may be resultant from any loss of cementation formed between sand particles. Therefore, it is important to clarify strength property of natural cemented sand on a slip surface subjected to dynamic shearing. In this study fast and cyclic shear characteristics of cemented sands were considered based on results of ring shear test. In laboratory, artificial cementation property was reproduced by adding a cement agent to sand. A series of dynamic ring shear tests was carried out on both of non-cemented and cemented sands. Consequently, it was shown that the importance of shear strength of cemented sand was recognized when we correctly assess the stability of the slope during or after an earthquake.

WATER QUALITY PURIFICATION TEST OF ARTIFICIAL BEACH USING GEOTEXTILE AND NATURAL ZEOLITE

湖沼などの閉鎖性水域では富栄養化に伴う水質汚濁や悪臭などが問題となっており，その対策として，排水中の窒素・リンの規制や下水道の整備が推進されているが，あわせて水域内の浄化対策がさらに必要である．本文では，ジオテキスタイルと天然ゼオライトを用いた人工なぎさを提案する．人工なぎさは，天然ゼオライトとそこで生成される生物膜の浄化効果を期待して，天然ゼオライトもしくは玉砂利を充填したジオテキスタイル製大型土嚢と透水シートにより湖岸に囲繞堤を築造し，堤内に天然ゼオライトを敷設するものである．諏訪湖湖岸において実施した実証実験について論じ，現地調査および水質調査の結果に基づいて，提案法の有効性を示した．