Crack propagation behavior in mass concrete of hydropower house substructures under cyclic internal water pressure loadings

The internal water pressure (IWP) in hydropower house substructures should be not seen merely as a static loading that acts on the substructure all at once, but rather as a cyclic one that repeatedly acts on the substructure for many times over its life cycle. Previous work has only focused on the static structural performance of hydropower house substructures. A neglected area is how cyclic IWP loadings would degenerate the structural performance of a hydropower house substructure. The aim of this work is thus to investigate the crack propagation behavior in mass concrete of hydropower house substructures with cyclic IWP loadings considered. The extended finite element method based on the ABAQUS code is used to model the crack propagation behavior. The intake c-cross-section of the Laxiwa hydropower house substructure is numerically modeled with axisymmetric elements. A major finding is the blocking effect of the slope on the upward-sliding behavior of the steel liner. The blocking effect should lead to concentrated steel-to-concrete IWP loading transfers at the slope-cutting constructions, which allow the initial cracks to propagate into the mass concrete under the cyclic IWP loadings. Another major finding is concerning the crack propagation from the turbine floor down into the mass concrete adjacent to the generator pedestal when a relatively stiff membrane (e.g. Em=3 MPa) is employed. This study has found noticeable stiffness degradation of the hydropower house substructure as the IWP loading repeats. The insights gained from this study may be of assistance to hydroelectric power plant designers and operators.