A device designed for simulating HM behavior of compacted GMZ01 bentonite

During the long-term operation of a conceptual multi-barrier deep geological repository for disposal of high-level nuclear waste, performance of the artificial barrier system (compacted bentonite) with consideration of influences of the surrounding rocks has to be evaluated for tens of thousands of years. Numerical simulation technology could be one of the most effective assessment methods. In order to have confidence in the prediction of the coupled hydraulic and mechanical processes occurring within the engineered clay barrier, a comparison between calculated and observed results is essential for validation and verification. For this purpose, a new Hydro-Mechanical (HM) device was designed in this paper, in which compacted GMZ01 bentonite specimen was embedded into a hollow Beishan granite column, which was tightly fixed by a closure metal framework. Relative humidity and pressure sensors were employed for monitoring behavior of the compacted bentonite during hydration, in order to observe the HM coupling performance of the compacted bentonite with consideration of influences of surrounding rocks at room temperature. The newly-developed test device includes three parts, a bottom plug, a cylindrical metal cell body and a top plug, which were tightly fixed together with four screws to form a confined (constant volume) closure system. Relative humidity and pressure sensors were implemented. Relative humidity sensors were calibrated before installation. With this newly-developed device, the GMZ01 bentonite-Beishan granite specimen was submitted to hydration. Some interesting preliminary results of the HM behavior of the compacted GMZ01 bentonite with consideration of the bentonite/rock interactions were obtained and discussed.