Study on the propagation of interface crack of young concrete lining and rock under blasting load

In the construction of water conservancy and hydropower project,young concrete lining structure is often affected by blasting load. Young concrete has a lot of micro-fractures with random distribution,which are easier to propagate and connect under blasting load. This paper focuses on the calculation on dynamic stress intensity factors of bond interface crack of concrete-rock according to concrete age. Result shows that different incidence angles of stress wave lead to different crack propagation mechanisms. Under the normal incidence of impact load,the bonding interface crack propagation of the concrete lining is mainly caused by reflection tensile stress,which forms from the free surface. With horizontal incidence of stress wave,the bond interface crack propagation of concrete lining is affected by concrete age. With the increase of concrete age,the elasticity modulus margin between concrete and rock decreases gradually,and the crack propagation form changes from shear failure to tensile damage.