Experimental Study on Broken Area Evolution Characteristics and Crack Propagation Rules of Water Jet Impacting Concrete with Precracks

Abstract

In the fields of concrete structure maintenance and emergency demolition, high-pressure water jet breaking technology shows a multitude of advantages, having broad application in future. The propagation rule of internal cracks in concrete is the fundamental issue of the high-pressure water jet concrete-breaking mechanism because it is related to the accuracy and safety of the technology and can promote its further development. In order to observe the propagation of cracks in concrete intuitively, transparent concrete-like materials with precracks were built in this study, and the transient process of broken area evolution and crack propagation under water jet impact in time and space was recorded with the help of a high-speed camera system. The results show that the existence of precracks significantly increases the efficiency and degree of water jet fracture, which manifests increasing the number of cracks, promoting the development of cracks in all directions, and enhancing the penetration speed. The vertical precracks can guide more failure in the axial direction of the water jet, and the horizontal precracks are beneficial to the crack propagation in the radial direction. More secondary cracks can be generated from the precracks, which will consume much more energy in the initiation and propagation of these cracks, resulting in the inadequate development of erosion hole dimension, compared to the concrete without precracks.