The tunnel excavation stability analysis for the high level radioactive waste repository-Beishan area as a example

The tunnel stability analysis plays a very important role in the high level radioactive waste (HLW) repository safety assessment, which not only include the tunnel excavation stability analysis, but also include the tunnel long-time stability analysis under the muti-physical field coupled condition. On the basis of the site selection and assessment for the high level waste repository of Beishan site, Gansu province, The tunnel excavation stability was analyzed and studied through the analysis method and the numerical modeling method. Results show: the rock strength is very high, and the geological stress is relatively low in this area. The displacement is very small around the tunnel, the maximum of displacement is only 3.7 mm around the tunnel after the tunnel excavation, the more larger of the tunnel diameter the more bigger of the displacement around the tunnel, there is no plastic damage point and plastic damage zone around the tunnel, that's to say the tunnel can stay a self- stability condition after excavation when the tunnels depth locate in the depth from 0 to -700 m under the ground surface. (authors)