Seismic Stability of Tunnels at the Kapchagai Hydropower Plant

Abstract

Results are presented of a full-scale study to assess the seismic stability of the spillway tunnels at the Kapchagai HPP in connection with an increase in the seismic rating of the site. Tests of the concrete used in the tunnel lining and of the surrounding rock determined the physical and mechanical properties of the materials and calculations were carried out for an earthquake load of intensity 8 on the facility. Calculations were carried out using the Tunnel' program package (developed by the authors) and ANSYS program package. Zones were identified in the tunnel lining where hazardous tensile stresses may potentially occur. It is shown that the existing spillway tunnels are seismically stable.