摘 要 膨潤土具有良好的阻隔能力，即低滲透性、低乾縮量、高熱傳導度和高回脹性，故世界各國常將其選為高放射性廢棄物處置場中的候選緩衝材料。台灣四面環海，未來高放射性廢棄物處置場的場址亦可能瀕臨海邊，故海水入侵後引致膨潤土的回脹行為有進一步研究的必要，本文探討含有蒙脫石黏土礦物的鈉型膨潤土，在處置區域受高放射性廢棄物衰變熱、地溫梯度的影響及含鹽地下水入侵的共同作用下，對緩衝材料的回脹行為可能引發的效應進行相關研究。因此，本文以不同乾密度的壓實膨潤土，分別在不同溫度、不同氯化鈉濃度溶液中，進行回脹試驗。由於處置場環境的複雜性，在此領域進行各項因子耦合效應的實驗研究過於複雜且較為少見，故本文採用田永銘（2001）所改良之回脹應變、回脹壓力試驗儀器。輔以試驗溶液上覆蓋矽油油膜，解決高溫時蒸發量大及熱散失的問題，以便模擬實驗環境處於高溫及高氯化鈉溶液濃度之狀態。此外，過去對於回脹性質的相關公式僅能針對特定條件做定性的評估，不易獲致定量化的預測模式，本文利用田永銘（1992）建立之遲延回脹模式，以明確的物理意義預測完整之回脹歷程。 Abstract Bentonite possesses good characteristics of isolation, low permeability, low shrinkage, highly thermal conductivity and highly swelling potential. Therefore, bentonite has been considered as an accepted buffer material of the world for repositories of high-level radioactive wastes. Taiwan is encircled by sea, the repository sites may be near to the sea in the future. Therefore, it is further necessary to study about swelling behavior of bentonite induced by seawater incursion. In this study, it is finished that sodium-bentonite containing montmorillonite bring about various effects for swelling behavior of buffer materials when the substance is suffering all affects of heat decay, geothermal gradient and groundwater containing salt incursion in the repositories. The compacted bentonite is used to investigate swelling behaviors through several tests at various dry densities, temperatures and sodium chloride solutions. It is hardly to proceed with experiments of coupled processes during the various factors because repository environment is very complex and the laboratory tests is difficult and few in the study field. Therefore, this study is adopted by Tien（2001）designing the test equipment and method for measuring swelling strain and swelling pressure of compacted bentonite. In order to simulate experiment environments applying in the high temperature and sodium chloride solution concentration, the solution was covered with a thickness of 1 mm by silicone fluids oil membrane to solve the problems of large evaporation and heat dissipating in high temperature. Furthermore, it is only obtained by qualitative evaluation of specific conditions for the formula of swelling property not easily acquired the quantitative predictable model in the past. This study is used by the delay swell model of Tien（1992）to simulate a complete swelling mechanism according to clear physical meanings
