Dynamic Fracture Toughness Tests on Limestone

Abstract

: Limestone being sedimentary rock contains multiple bedding planes, which has vertical cracks or joints. As explosives apply high dynamic loading rate during blasting i.e. rock fragmentation & comminution process, the measure of critical SIF (stress intensity factor) is pertinent to be measured and is known as dynamic fracture toughness of limestone. In order to investigate the influence of several factors on the mode-I fracture toughness and fracture behavior of limestone, dynamic fracture toughness tests (mode-I) were conducted under various conditions of loading rate. The microstructure of rocks was also investigated to understand the dynamic fracture toughness and fracture mechanism of limestone. This paper deals with results of 11 limestone specimen subjected to dynamic fracture toughness tests. It was observed that crack surface velocity increases with increase in dynamic fracture toughness. The fracture velocity also increases with increase in dynamic fracture toughness. The fracture velocity in limestone increases between 1.14-5.09 times with increased fracture toughness. The crack surface velocity of limestone increases between 1.39-3.09 times with increase in dynamic fracture toughness.