| 摘要: | 膨潤土被應用於當作緩衝材料，做為深地層處置場高放射性廢棄物之工程障壁。處置孔在安裝完處置罐及緩衝材後，地下水從母岩逐漸入侵緩衝材內並使其逐漸飽和。處置場緩衝材的再飽和行為同時受到地下水及熱衰變之熱(Thermal)-水(Hydraulic)-力(Mechanical)耦合影響。
為了瞭解緩衝材料在不同密度之熱-水-力之耦合行為，藉參數試驗來求得密度1,400 kg/m³、1,500 kg/m³及1,600 kg/m³之緩衝材料熱傳導係數、水力傳導係數及土壤水分特性曲線相關參數，並利用攝取水試驗、溫度場分佈試驗及數值模擬分析，驗證實際熱-水-力耦合行為與數值模擬結果是否一致。
試驗結果得知，熱傳導係數隨密度及溫度提升而增加，相同溫度下，乾密度試體1,600 kg/m³熱傳導係數高於乾密度1,400 kg/m³；相同密度下，60°C試體熱傳導係數高於25°C試體。膨潤土回脹壓力隨膨潤土乾密度提生而增加，飽和水力傳導度隨膨潤土乾密度提生而下降，非飽和水力傳導度Abaqus模式推估結果高於vG-Mualem模式。水汽平衡法之試體體積修正結果近景攝影法與封蠟法無明顯區別，由於溫度影響水與空氣之介面張力及毛細半徑，土壤水分特性曲線隨溫度提升而下降。比較數值模擬與溫度場分佈試驗，溫度場數值模擬高估實際溫度。比較攝取水試驗與水-力參數耦合結果，數值模型設定Abaqus模式之非飽和相對水力傳導度高估實際含水量分佈；套入vG-Mualem模式則低估實際含水量分佈。
;bentonite is used to buffer material in an engineered barrier system for isolation of high-level radioactive wastes(HLW) in a repository. After emplacement of the buffer material, groundwater begins to be taken from the rock by the buffer. And the buffer becomes saturated gradually.
The resaturation of the buffer is considered a hydro-process occurring at elevated temperatures in the near-field of a repository. it is mainly affected by Thermal, Hydro and Mechanical factors, called T-H-M coupling effect.
In order to understand the thermal-hydraulic-mechanical coupling behavior of buffer materials at different dry densities. Through parameter test to obtain thermal conductivity, hydraulic conductivity and soil water characteristics curve with dry density 1,400 kg/m³, 1,500 kg/m³ and 1,600 kg/m³. And use water intake test, temperature distribution test and numerical simulation analysis to verify whether the actual thermal-hydraulic-mechanical coupling behavior is consistent with the numerical simulation results.
The test result shows that the thermal conductivity increases with the increase of density and temperature. At the same temperature, thermal conductivity of the dry density specimen 1,600 kg/m³ is higher than the dry density 1,400 kg/m³. At the same density, the thermal conductivity of the 60°C specimen is higher than that of the 25°C specimen. The swelling pressure of bentonite increases with the increase of dry density. Saturated hydraulic conductivity decreases with increasing dry density. Unsaturated hydraulic conductivity estimated by Abaqus model is higher than vG-Mualem model. There is no obvious difference between the close range photogrammetry and wax coating method in the volume correction result of the vapour equilibrium technique. Temperature affects the radius of the capillary tube and the pore radius of the air-water surface. Soil water characteristics curve decreases with increasing temperature. Comparing numerical simulation and temperature distribution test, the numerical simulation of temperature overestimates the actual temperature. Comparing the results of water intake test and hydraulic-mechanical parameter coupling. The numerical model sets the unsaturated relative hydraulic conductivity of the Abaqus model to overestimate the actual water content distribution.The numerical model sets the unsaturated relative hydraulic conductivity of the vG-Mualem model to underestimate the actual water content distribution |
