高放废物处置库中缓冲/回填材料膨胀特性研究进展

根据近年来国内外学者的研究成果,重点从缓冲/回填材料膨胀性试验方法、影响膨胀性的主要因素和膨胀机理等方面总结了该课题的研究现状及进展,得到如下认识:(1)在试验方法方面,根据加载条件可将膨胀率试验分为有荷和无荷两种形式,而膨胀力试验方法主要有三种,不同试验方法获得的膨胀力存在差别;(2)三向膨胀试验为研究缓冲/回填材料膨胀性各向异性提供了可行的途径,柔性边界试验可模拟更真实的膨胀环境;(3)影响缓冲/回填材料膨胀特性的主要因素包括矿物成分、孔隙溶液性质、干密度、初始含水率和添加剂性质等;(4)针对膨润土/添加剂混合物的膨胀性,学界基于膨润土含量、密度、孔隙比等参数提出了多种预测模型;(5)缓冲/回填材料的干密度和试样尺寸会影响其收缩特性。针对目前该课题的研究现状和不足,提出了今后的研究重点和方向,主要包括复杂耦合条件下的膨胀特性、三向膨胀试验与多边界条件试验、具体应用研究、收缩特性研究、添加剂与膨润土相互作用机制、大尺度长期室内模型试验和原位试验等。

Advances on Swelling Properties of Buffer/backfill Materialsin High-levelRadioactive Waste Geological Repository

The swelling properties of buffer/backfill materials in high level radioactive waste (HLW) repository are one of the significant indexes of their buffer/backfill properties. Based on previous research findings by international and domestic scholars, this paper summarizes current research status and advances from such aspects as follows: swelling test methods for buffer/backfill materials, the main factors affecting swelling properties and shrinkage properties. And the following understanding can be obtained: (1) In terms of test methods, swelling rate tests can be divided into loaded and unloaded according to the loading condition. There are mainly three types of test methods. And there are significant differences in the swelling pressure obtained by various test methods; (2) Three-directional swelling test provides a feasible approach for studying the anisotropy of swelling properties of buffer/backfill materials, and flexible boundary test can simulate more realistic conditions; (3) The main factors affecting the swelling properties include mineral components, properties of pore solution, dry density, initial water content, and properties of additives; (4) In terms of the swelling properties of the mixture of bentonite and additives, various prediction methods are proposed by the academia based on such parameters as content of bentonite, density, and void ratio; (5) The dry density and samples size effectively affect the shrinkage properties. Finally, contrapose the research status and existing deficiencies, some important research topics which should be stressed are proposed, including the swelling properties under complex coupling conditions, three-directional swelling tests, multi-boundary conditions tests, applied research, shrinkage properties research, the mechanism of interaction between additives and bentonite, larges-cale long-term indoor model tests, and in-situ tests.