Simplified evaluation for swelling characteristics of bentonites   总被引：9，自引：0，他引：9  

Hideo Komine   《Engineering Geology》2004,71(3-4):265-279

Bentonite is currently planned to be used as buffer and backfill materials for repositories of high-level nuclear waste because these materials must have the swelling characteristics to seal the waste. In the design for buffer and backfill materials, we must choose the adequate bentonite among many kinds of bentonite in the world. The database of the swelling characteristics of various bentonites and its evaluation will be available when we will select the adequate bentonite. For this purpose, this study performed the laboratory tests on the swelling pressure and swelling deformation of four kinds of bentonite produced in Japan and the United States. These bentonites have different physicochemical properties. This study investigated the characteristics of swelling pressure and swelling deformation from the viewpoint of the physicochemical properties of each bentonite. Furthermore, this study also proposed the simplified evaluation of swelling characteristics of various bentonites on the basis of microscopic analysis.  相似文献   

Can the visualization of rip currents prevent drowning accidents? Consideration of the effect of optimism bias     

Endo  Shintaro  Shimada  Ryo  Ishikawa  Toshinori  Komine  Tsutomu 《Natural Hazards》2022,110(3):2017-2033

Drowning accidents at beach in Japan are caused by rip currents. To reduce these accidents, a new technology that can detect rip currents and notify beachgoers by using the Internet of Things (IoT) and Artificial Intelligence (AI) was proposed. However, studies on the effect of visualizing rip currents or considering the effect of optimism bias have not been conducted. This study investigates if visualization of rip currents might help in preventing drowning accidents, while considering the effect of optimism bias. The participants were 90 Japanese beachgoers. They were asked to answer questions based on their knowledge of the beach and rip currents, their optimism bias regarding rip currents, and awareness with or without visualization. The results of the analyses suggest that despite optimism bias, the visualization of rip currents increases the tendency of beachgoers to perceive and avoid rip currents. As described above, it was found that by visualizing the rip current, beachgoers were able to perceive and avoid rip currents. In addition, an understanding of rip currents is positively related to the intent to avoid rip currents even when rip currents are visualized. Therefore, it is necessary not only to enhance the avoidance tendency by visualizing rip currents, but also to further enhance knowledge of beachgoers to deepen the understanding of rip currents including the danger associated and methods to avoid them.

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Dynamic compaction properties of bentonite-based materials     

Hiroshi Ito  Hideo Komine 《Engineering Geology》2008,98(3-4):133-143

Dynamic compaction tests of bentonite-based materials (BBMs) with 100, 70 and 50% bentonite contents have been performed using five powdery bentonites with different physicochemical properties to establish the simplified evaluation method for dynamic compaction properties of BBMs. For a given bentonite content and a total compaction energy condition, the maximum dry density, ρ_dmax, and the optimum water content, w_opt, which are well-known indexes of compaction properties, for BBMs were determined according to the type of bentonite used for BBMs. For evaluation of those values of BBMs derived in this study, the plastic limit of BBM, w_pbbm, was defined as the plastic limit that was measured using the sample pulverized to a maximum grain size of less than 425 μm in the case of BBM with sand having a maximum grain size of more than 425 μm and was measured using the powdery bentonite itself in the case of BBM without sand. This study proposed equations for evaluating ρ_dmax and w_opt of BBMs with more than 50% bentonite content under the total compaction energy conditions of 551–2755 kN-m/m³ using w_pbbm. Finally, we related the equations derived in this study to the equation for evaluating hydraulic properties of compacted BBMs proposed in previous work and proposed the preparation method of BBMs with more than 50% bentonite content for constructing BBM buffer by in-situ compaction method.  相似文献