Experimental investigation of fatigue crack propagation in interbedded marble under multilevel cyclic uniaxial compressive loads
Yu Wang, Huajun Meng, Dayu Long
Abstract
Abstract Multilevel cyclic loading–unloading uniaxial compressive testing combined with real‐time acoustic emission monitoring (AE) and post‐test computed tomography (CT) scanning was employed to investigate the anisotropic cracking propagation and the type of crack classification for interbedded marble. An AE parameter method using RA (ratio of rise time to amplitude) and AF (ratio of AE counts to duration) is used to classify cracking event modes and propagation characteristics. Results show that the fatigue strength and lifetime first decreases and then increases with increasing interbed orientation, and they reach a minimum for rock with an interbed orientation of 30°. In addition, the distribution of RA values and AF values is strongly influenced by the rock structure, especially the interbeds. Moreover, CT imaging reveals the difference between the cracking mode and it is found that the cracking propagation pattern is structurally dependent. An increase of RA value provides an early warning for rock failure.