Asymptotic fields at the tip of a cohesive frictional crack growing at the bi-material interface between a dam and the foundation rock

• An interfacial crack growing between dissimilar media is analyzed.
• A cohesive-frictional crack model is applied.
• An asymptotic expansion around the fictitious crack tip is obtained.
• The new expansion proposed is valid for many commonly used separation laws.
• The assumption of mean values of elastic parameters is not conservative.

One of the weakest points in concrete dams occurs at the rock/concrete interface at the base of the dam. This has prompted interest in studying the interface laws that can best represent the interaction between damage due to normal stresses and damage caused by tangential stresses (traction–separation law) in the process zone, within the framework of the cohesive crack model. Karihaloo and Xiao (2008) proposed a model considering the Coulomb friction between the crack faces, instead of a tangential cohesive relationship. This model is called the cohesive-frictional crack model,and it is different from the model of frictional contact of crack faces, because the friction operates when the crack faces are open. The above mentioned authors published asymptotic expansions at a cohesive crack tip propagating along an interface between similar elastic media. In the present paper, a new asymptotic expansion is presented and applied to the case of a crack propagating at a bi-material interface between a dam and the foundation rock.