對於低放射性廢棄物最終處置場之多重障壁系統，膨潤土為最重要之緩衝材料，因膨潤土具有良好的吸水膨脹與高吸附核種之特性，可自癒材料並降低水力傳導係數，以減少地下水外滲以及延緩核種外流，但隨著地球氣候變遷，面臨冰河期的到來也將是一個可預知的事件，低放射性廢棄物處置場運行年數高達上百年，面臨環境的降溫能否抵抗，是未來低放射性廢棄物處置場的重要設計因素。目前針對純膨潤土受到環境降溫實驗較少，多部分皆以高溫為取向，因此本研究將使用不同配比之純膨潤土來進行單向度膨脹率試驗，來模擬放射性廢棄物處置場降溫所受之影響。目前針對膨潤土膨脹特性行為之分析較少，本研究探討單元分析軟體Triax對於膨潤土分析之可靠性，Triax中雙重結構擬塑性黏土組成律模式(DSHC model)用以描述膨脹性土壤吸水膨脹、高基質吸力等水-力耦合特性較佳，後續將針對膨潤土受乾溼循環參數校正，以及溫度參數之校正驗證模擬降溫之可行性。本研究校正結果應用於乾溼循環模擬表現良好，建議未來可增加實驗組數增加精確性，但針對溫度參數此模型計算較為簡易，表現較不明顯，建議未來模型可加入更複雜之運算模式來提高溫度參數之靈敏度。

For the multi-barrier system of the low-level radioactive disposal facility, bentonite is the most important buffer material. Because bentonite has high swelling potential and high adsorption ability. These abilities make itself a sealing material and reduce hydraulic conductivity which reduces the possibility of nuclear extravasation by groundwater. However, there will be a foreseen ice age in the future due to the climate change. The low-level radioactive waste disposal site will operate over hundreds of years, so low temperature resistance must be an important design factor for the future radioactive waste disposal sites. At present, there are few experiments on pure bentonite subjected to environmental cooling while the majority are oriented to high temperature. Therefore, this study will use different dry density of pure bentonite to carry out the swelling deformation rate test to simulate the impact of the cooling of the radioactive waste disposal site. At present, there are few analysis on the swelling behavior of bentonite. This study will focus on the unit analysis software Triax for the analysis of bentonite. The Double Structure Hypoplasticity Clay Model (DSHC model) in Triax is used to describe the hydro-mechanical coupling characteristics of bentonite which has better performance of swelling and high suction. Bentonite parametric study focused on dry and wet cycle, while temperature parameter will be calibrated to verify feasibility of cooling simulation. The calibration results of this research have been applied to dry and wet cycle simulations and performed well. It is suggested that the number of experiment can be increased in the future to increase accuracy. However, the calculation of this model for temperature parameters is relatively simple and the performance is less sensitive. It is recommended that, in the future, models can be added with more complex calculation modes to improve the sensitivity of temperature parameters.

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