Coupled thermo-hydro-mechanical process in buffer material and self-healing effects with joints

缓冲材料的热-水-力耦合过程及接缝愈合效应

Within the multi-barrier system for high-level waste disposal,the technological gap formed by combined buffer material block becomes the weak part of buffer layer.In this paper,Gaomiaozi bentonite buffer material with technological gap was studied,the heat transfer induced by liquid water flow and water vapor was embedded into the energy conservation equation.Based on the Barcelona basic model,the coupled thermo-hydro-mechanical model of unsaturated bentonite was established by analyzing the swelling process of bentonite block and the compression process of joint material.The China-Mock-up test was adopted to compare the numerical calculation results with the test results so as to verify the rationality of the proposed model.On this basis,the effect of joint self-healing on dry density,thermal conductivity and permeability coefficient of buffer material was further analyzed.The results show that,with bentonite hydrating and swelling,the joint material gradually increases in dry density,and exhibits comparatively uniform hydraulic and thermal conductivity properties as compacted bentonite block.As a result,the buffer material gradually shifts to homogenization due to the coordinated deformation.

在高放废物处置库工程屏障系统中,缓冲材料砌块组合堆砌形成的技术接缝成为了缓冲层的薄弱部位。本文研究了技术接缝的高庙子(GMZ)膨润土缓冲材料,将液态水流动和水蒸汽迁移引起的传热嵌入到能量守恒方程之中,基于Barcelona基本模型,通过分析膨润土砌块的膨胀过程及接缝材料的压缩过程,建立了非饱和膨润土热-水-力耦合模型。然后以China-Mock-up试验为例,将数值计算结果与试验结果进行对比,以验证所提模型的合理性。在此基础上,进一步分析了接缝愈合效应对缓冲材料的干密度、导热系数和渗透系数的影响。结果表明,随着缓冲材料的水化膨胀,接缝材料的干密度逐渐增大,导热性能和防渗性能逐渐与膨润土砌块趋于一致,缓冲材料在协调变形的作用下逐渐向均质化发展。