Abstract
Taking the clay rock from the Tamusu pre-selected area of China’s high-level radioactive waste geological repository as the research background. Using the methods of triaxial compression testing, X-ray diffraction and microscopic analysis, the main mineral composition, structure and mechanical properties of clay rock under different confining pressures were systematically obtained. Combined with the classical elastic parameter estimation methods at home and abroad, the elastic modulus of the clay rock in the Tamusu pre-selected area is estimated. It finds that the classical elastic parameter estimation method has a large error with the actual test value when calculating the elastic modulus of Tamusu clay rock. The maximum error can reach 788%, and the error decreases with the increase of confining pressure, however, the minimum error is still also 46%. In order to establish the deformation evaluation index suitable for the clay rock in the Tamusu pre-selected area of high-level radioactive waste, considering the influence of the mineral properties and structure of the clay rock on the macro-mechanics properties, a new method for estimating the elastic parameters of the clay rock was established. Compared with the classic elastic parameter estimation method, the maximum error is reduced to 33% and the minimum error is only 2%. Therefore, we suggest that the new elastic parameter estimation method proposed here may be used to evaluate and predict the elastic modulus parameters of the clay rock in the Tamusu pre-selected area for geological disposal of high-level radioactive waste in China.
Highlights
The deep geological disposal of high-level radioactive waste (HLW) is a systematic and complex project
Reuss et al.'s classical elastic parameter estimation method test samples are both hard rocks such as igneous rocks, while clay rock in the Tamusu pre-selected area is a kind of sedimentary rock, which is structurally different from hard rocks
The obtained by the elastic parameter estimation method maximum error is reduced to 389% under the condition proposed in this paper is more consistent with the actual of normal temperature triaxial 5 MPa, and the maximum test value, which can more accurately predict and error is reduced to 171% under normal temperature evaluate the elastic modulus of the clay rock host rock in triaxial condition of 10 MPa, but there is still a large the geological disposal for HLW
Summary
The deep geological disposal of high-level radioactive waste (HLW) is a systematic and complex project. The research on granite as the host rock of the HLW geological repository is much earlier than that of clay rock. Technology and Industry for National Defense, China, officially approved the construction proposal of the underground laboratory for the geological disposal of high-level radioactive waste in Beishan, Gansu, marking the geological disposal of HLW granite in China has officially entered the underground laboratory stage (Wang, 2019). Technology and Industry for National Defense, China, approved the "Clay Rock Project" and made the Tamusu area of the Bayin Gobi Basin in Inner Mongolia as the pre-selected area for the HLW geological repository, the research mainly focuses on the site selection and suitability evaluation of the pre-selected area (Yuan et al, 2018; Xiang et al, 2018; Wang et al, 2018; Gong, 2017). The research on the mechanics of the clay rock in the area is relatively basic (Wan, 2018; Hu, 2014; Hu et al, 2014; Hu et al, 2020; Xue et al, 2016; Rao, 2018)
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