Research on stability of surrounding rock mass for intake tunnel due to swelling rock

The swelling rock usually induces surrounding rock mass be extruded largely or floor lift by time even the support and surrounding rock mass be damaged or destroyed in practice. The geologic characteristic of the tunnel No.7 for Shanxi Wanjiazhai Yellow River Diversion Project is sandstone and mudstone distributing interactively and has 3-4 layers swelling rock through the tunnel. Numerical analysis with viscoelasto-plastic model has been done to analyze the process of excavation and support procedures. The numerical results show that swelling deformation has high effect on stability and mechanical behavior of support structure. Therefore, the displacement, stress and strain, seepage pressure and water pressure should be measured during the tunnel operating.