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Yong-Gui Chen is a professor in the College of Civil Engineering, Tongji University, Shanghai, China. He obtained his BEng and PhD degrees from Central South University in Hunan Province, China. He has extensive experience in research in the fields of unsaturated soils, geo-environmental engineering, urban engineering geology, and contaminated soils. He has been awarded the 14th Youth Geological Science and Technology Award of the China Geological Society, the National Science Fund for Outstanding Young Scholars (in 2014), the First Prize of the Natural Science Award of the Ministry of Education, China (in 2018), the National Science Fund for Distinguished Young Scholars (in 2021), and the Key Program of National Natural Science Foundation of China (in 2024). He has published over 150 papers in international journals and 3 industry standards in his research areas.
Outline
Compacted bentonite blocks are proposed for buffer barriers in deep geological repositories for high-level radioactive waste (HLRW) disposal. These blocks, manufactured through uniaxial compression in molds, exhibit heterogeneity that may impact long-term buffer performance. This study focuses on the physical and hydro-mechanical heterogeneity of full-scale blocks induced by the compaction process. Sector-shaped blocks, with radii of 600 mm and 1200 mm and a height of 200 mm, were axially compressed. Key parameters, including water content, dry density, elasticity modulus, swelling pressure, and permeability, were measured to assess the heterogeneity. Results show that the heterogeneity in the upper layer is primarily caused by differences in drainage and gas expulsion pathways. As depth increases, water content and dry density become more correlated. Hydro-mechanical behavior is largely controlled by dry density, but its fluctuation ratio is much higher than that of dry density. Regarding the microstructure, pore structure heterogeneity follows the order: corner regions > edge regions > center regions, and upper layer > middle layer > lower layer. Vertical microcracks also develop to varying degrees, increasing the anisotropy of the blocks. Upon these observations, the study thoroughly discusses the feasibility and challenges of reckoning the hydro-mechanical properties of blocks using dry density distribution alongside laboratory-scale data. Additionally, it proposes an indicator to evaluate the overall heterogeneity of buffer blocks. These findings highlight the inherent heterogeneity of compacted bentonite blocks at the engineering scale, providing valuable insights for future experiments and simulations.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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