施工接缝对缓冲材料水–力特性影响研究进展

在详细阐述处置库中施工接缝封闭和自愈合过程的基础上,全面回顾和总结了有关施工接缝对缓冲材料膨胀力、渗透系数、界面水力强度和自愈合性能影响的研究成果。接缝的存在使缓冲材料的膨胀性能及防渗性能明显弱化,特别是在处置库运行初期,接缝作为力学薄弱区极有可能在高水压环境下发生水力劈裂。总体而言,考虑接缝对缓冲材料水–力特性影响的试验研究还远远不够,主要是通过物理试验,采用整体平均化的方法来分析接缝对缓冲材料总体膨胀力和渗透系数的影响,这种方法的不足在于难以表述接缝处真实的水–力特性指标;现有试验仪器不能实时监测接触界面膨胀力和孔隙水压力的分布情况,无法有效揭示界面的应力传递特征与水分传输特性,这也是导致相关机理分析缺乏的一个重要原因。为此,提出在细化影响因素、深入机理分析及数值模拟等方面开展进一步研究的建议。

Advances in hydro-mechanical behaviors of buffer materials under effect of technological gaps

The self-sealing and self-healing behaviors of technological gaps in a high-level radioactive waste repository are analyzed. The systematical findings are summarized based on the previous studies on the effects of technological gaps on the swelling pressure, permeability, fracturing pressure and self-sealing properties. The results indicate that the presence of technological gaps strongly weakens the swelling potential and water tightness of buffer materials. At the early stage of a real repository development, hydraulic fracturing is likely to be induced along these interfaces under high water pressure. Generally available achievements in this area are quite limited. In the tests, the total average methods are employed to study the mean swelling pressure and permeability of buffer materials. However, the hydro-mechanical behaviors of bentonite within gaps cannot be characterized. Several testing devices are specially designed to monitor the total pressure along the interface, except that the effective swelling pressure and pore water pressure cannot be distinguished. These disadvantages result in great difficulties in mechanism analysis of sealing and healing behaviors of technological gaps. Finally, some suggestions are proposed for further researches.