日本語フィールド
著者：Kurishima, A., Ariyama, H., Sindete, M. J. and Hino, T.題名：Fundamental study on distribution of crust layer and groundwater level in Saga lowland発表情報：Proceeding of the 21st Southeast Asian Geotechnical Conference and 4th AGSSEA Conference (SEAGC-AGSSEA 2023)キーワード：Soft ground, Crust layer, groundwater level, Ground foundation概要：抄録：The lowland areas of Saga Prefecture, located in Kyushu, the southern island of Japan, are characterized by a distinctive soil surface known as a crust layer, formed due to natural weathering and human activities. To countermeasure soft ground, methods such as soil improved columns and wooden piles are used. Wooden piles effectiveness has been proved to last for several decades through history, thanks to the construction standards which imply to drive the wooden pile below the groundwater level (anaerobic environment). but groundwater level fluctuations can cause wooden piles to rot quickly in aerobic environments. This study aimed to locate the appropriate depth of wooden piles during implementation by using the crust layer as a prior investigation for a better countermeasure. The crust layer is deposited on top of a dark gray cohesive soil layer with a brownish color (around 2m depth from the natural ground level), and the thickness was quantified based on archived geological columns. This research analyzed the thickness of the crust layer and groundwater levels using data from the National Land Numerical Information on the 500 meters mesh of the Saga lowland. The distribution of the thick crust layer of about 1m in the Saga lowland is more likely to be observed in areas of natural terrestrialization. The analysis found that areas with thicker crust layers are near Saga City and Takeo City. The groundwater level in the Shiroishi area of the Saga lowland has become shallower due to the influence of the Kasegawa Dam. Here, we developed a system database to examine the distributions of the crust layer and groundwater level for a better implementation of soft ground countermeasures. The study's findings can help locate the appropriate depth of wooden piles during implementation, thus preventing them from rotting due to groundwater level fluctuations and reduce the construction cost.英語フィールド
Author：Kurishima, A., Ariyama, H., Sindete, M. J. and Hino, T.Title：Fundamental study on distribution of crust layer and groundwater level in Saga lowlandAnnouncement information:Proceeding of the 21st Southeast Asian Geotechnical Conference and 4th AGSSEA Conference (SEAGC-AGSSEA 2023)Keyword：Soft ground, Crust layer, groundwater level, Ground foundationAn abstract：The lowland areas of Saga Prefecture, located in Kyushu, the southern island of Japan, are characterized by a distinctive soil surface known as a crust layer, formed due to natural weathering and human activities. To countermeasure soft ground, methods such as soil improved columns and wooden piles are used. Wooden piles effectiveness has been proved to last for several decades through history, thanks to the construction standards which imply to drive the wooden pile below the groundwater level (anaerobic environment). but groundwater level fluctuations can cause wooden piles to rot quickly in aerobic environments. This study aimed to locate the appropriate depth of wooden piles during implementation by using the crust layer as a prior investigation for a better countermeasure. The crust layer is deposited on top of a dark gray cohesive soil layer with a brownish color (around 2m depth from the natural ground level), and the thickness was quantified based on archived geological columns. This research analyzed the thickness of the crust layer and groundwater levels using data from the National Land Numerical Information on the 500 meters mesh of the Saga lowland. The distribution of the thick crust layer of about 1m in the Saga lowland is more likely to be observed in areas of natural terrestrialization. The analysis found that areas with thicker crust layers are near Saga City and Takeo City. The groundwater level in the Shiroishi area of the Saga lowland has become shallower due to the influence of the Kasegawa Dam. Here, we developed a system database to examine the distributions of the crust layer and groundwater level for a better implementation of soft ground countermeasures. The study's findings can help locate the appropriate depth of wooden piles during implementation, thus preventing them from rotting due to groundwater level fluctuations and reduce the construction cost.