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

Abstract

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.

Keywords

buffer material / thermo-hydro-mechanical coupling / joints / self-healing effect

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