Bentonite Permeability at Elevated Temperature
Bentonite Permeability at Elevated Temperature
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DOI：
10.3390/geosciences7010003
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发表时间：
2017-03-01
期刊：
影响因子：
2.7
通讯作者：
Wiseall, Andrew C.
中科院分区：
文献类型：
--
作者：
Daniels, Katherine A.;Harrington, Jon F.;Wiseall, Andrew C.
处置库的设计往往有利于放射性废物的地质处置，回填材料占据废物周围的空隙空间。回填材料必须能够承受放射性废物腐烂产生的高温，以防止其失效或降解，从而导致水力传导性增加和密封性能降低。四个实验研究温度对膨润土回填土渗透性的影响的结果。膨润土是一种粘土，由于其高膨胀能力和极低的渗透性，通常被提议作为处置库设计中的回填材料。实验在两套特制的温度控制装置中进行，该装置被设计成在4-6 MPa平均有效应力的测试范围内模拟各向同性压力和恒定体积条件。研究了膨润土在高达200 ℃的温度下热负荷期间的响应，扩展了先前考虑的温度范围。结果提供了膨润土的固有渗透率，总应力，膨胀压力和孔隙水压力在热循环过程中的细节。研究发现，膨润土的水力学性质对热负荷和边界条件的类型很敏感。然而，渗透率的变化不大，主要是由于水的粘度变化。因此，在150摄氏度以下，温度对膨润土的水力渗透性的影响最小。
Repository designs frequently favour geological disposal of radioactive waste with a backfill material occupying void space around the waste. The backfill material must tolerate the high temperatures produced by decaying radioactive waste to prevent its failure or degradation, leading to increased hydraulic conductivity and reduced sealing performance. The results of four experiments investigating the effect of temperature on the permeability of a bentonite backfill are presented. Bentonite is a clay commonly proposed as the backfill in repository designs because of its high swelling capacity and very low permeability. The experiments were conducted in two sets of purpose-built, temperature controlled apparatus, designed to simulate isotropic pressure and constant volume conditions within the testing range of 4-6 MPa average effective stress. The response of bentonite during thermal loading at temperatures up to 200 degrees C was investigated, extending the previously considered temperature range. The results provide details of bentonite's intrinsic permeability, total stress, swelling pressure and porewater pressure during thermal cycles. We find that bentonite's hydraulic properties are sensitive to thermal loading and the type of imposed boundary condition. However, the permeability change is not large and can mostly be accounted for by water viscosity changes. Thus, under 150 degrees C, temperature has a minimal impact on bentonite's hydraulic permeability.