NEAR-FIELD THERMO-MECHANICAL COUPLING SIMULATION RESEARCH ON THE MUDSTONE REPOSITORY WITH HIGH-LEVEL RADIOACTIVE WASTE

Based on the conceptual design of high-level radioactive waste disposal repository in China, combined with the design concept of high-level radioactive waste disposal repository in France and Belgium, the temperature-seepage-stress coupling plastic model was applied to simulate the thermodynamic response characteristics of clay nuclear waste disposal repository. The contribution degree of the influence of temperature field on stress site was quantitatively calculated and analyzed. The results show that without considering the seepage field, the nuclear waste disposal process is essentially a mechanical-thermal sequence coupling process. When the disposal begins, the whole temperature field shows a process of rapid growth, peak value, lasting for a period of time, slow decline, rapid decline and reaching equilibrium again. But there are some differences in different regions. The variation range of surrounding rock displacement field is generally between 1mm and 2mm. The displacement in some areas is large. Yet as time passed, the area with large displacement will gradually decrease to 1-2mm and tend to be stable. Through the coupling analysis of mechanics and mechanical-thermal sequence, it is found that the temperature field has a significant effect on the stress field. The contribution rate of thermal stress is between 18.1% and 39.4% and the average value is 27.9%. The result of this study can provide a scientific basis for the analysis of thermal-mechanical coupling mechanism of clay in nuclear waste disposal repository.