在最終處置場近場環境中主要受到熱–水力–力學–化學效應影響(即T-H-M-C效應)。這些耦合效應對緩衝材料的劣化有直接的影響，因此不同近場環境因子對緩衝材料回脹行為之影響必須加以分析釐清。 本研究將SPV 200膨潤土壓實至乾密度為1600 kg/m^3狀態，針對衰變熱、地下水化學、pH值與垂直應力效應，進行單向度回脹試驗、回脹壓力與水力傳導試驗，從研究結果顯示： (1)SPV 200膨潤土於65℃ 水–熱環境下，造成膨潤土回脹壓力迅速發展，且回脹壓力隨著溫度提高而降低； (2)SPV 200膨潤土於氯化鈉與氯化鈣環境下，回脹壓力隨著陽離子濃度提升而降低，其中氯化鈉效應下對回脹壓力影響較大； (3)當 SPV 200膨潤土處於pH值<13溶液中，對回脹壓力沒有明顯影響； (4)由XRD與ICP分析結果顯示，SPV 200膨潤土於氫氧化鈉[1.0M]系統中，蒙脫石與石英礦物有減少趨勢，且矽離子有明顯溶出現象； (5)單向度回脹試驗顯示，垂直應力提升時，壓縮了膨潤土的回脹。但膨潤土於海水效應中，垂直應力越高，使得陽離子對膨潤土回脹影響程度越小。;In a final disposal site for radioactive wastes, the evolution of the near field is mainly controlled by the thermo-hydro-mechanical-chemical (T-H-M-C) effects. The coupling effects have a direct impact on the deterioration of the buffer material, and therefore the effects of various near field environmental factors on the swelling behavior of the buffer material must be analyzed. In this study, SPV 200 bentonite compacted to a dry density of 1600 kg/m^3 was tested for one-dimensional swelling pressures, with considerations on simulation decay heat, groundwater chemistry, pH environment, and the vertical stress effect. Results from the study show: (1) SPV 200 bentonite at 65℃ water - heat solution exhibited a rapid development of bentonite swelling pressures, and increases in temperature cause decreases in swelling pressure; (2) in NaCl and CaCl2 solution, the swelling pressure of bentonite decreases with increasing cation concentration, and the effect of NaCl on swelling pressure is more pronounced; (3) at solutions with pH < 13, no significant reduction on swelling pressure was observed; (4) as illustrated by XRD and ICP analysis, SPV 200 bentonite in NaOH [1.0M] solution shows decreases in montmorillonite and quartz minerals, while the Si ions exhibits obvious increase; (5) one-dimensional swelling tests showed that the amount of swelling is highly dependent on the vertical stresses applied on bentonite.
