Structural performance of tunnel linings under tectonic fault displacement

The paper presents the results of comparative numerical analyses of design alternatives for the permanent lining of Hydraulic Tunnel No. 3 at the Rogun Hydropower Plant in the zone of intersection with the Ionakhsh tectonic fault. Three tunnel lining design options were considered. The comparison of structural alternatives was carried out based on the ability of the linings to accommodate ground movements within the Ionakhsh fault zone, where ongoing tectonic activity has been recorded. The behavior of the lining under fault-induced displacements was investigated using a three-dimensional finite element method, taking into account nonlinear contact deformations associated with shear and opening along the lining deformation joints, as well as at the interface between the tunnel and the surrounding rock mass.