Energy release rate due to friction at bimaterial interface in dams

The interface between concrete dam and rock foundation is one of the most important regions governing the strength and stability of gravity dams. Many researchers have attempted to extend the fracture mechanics approach to study this rock concrete interface assuming stress free crack surfaces. In a real-life situation, because of the combined compression and shear loading, the crack faces come in contact resulting in a sizeable contact zone near the crack tip. Thus, frictional contact of the crack surfaces cannot be neglected. The frictional contact alters the stress singularity to become either weaker or stronger than the inverse square root singularity observed in homogeneous crack problems. Consequently, the strain-energy release rate as conventionally defined, either vanishes or becomes unbounded and thus cannot be used as a fracture parameter. In this work, an attempt is made to include the effect of friction associated with the sliding of crack surfaces and compute the energy dissipated during crack propagation. It is shown that the total energy release rate decreases with crack length when friction is accounted for between the rock-concrete interface in gravity dams.