Deformation and cracking characteristics of ring-shaped granite with inclusion under diametrical compression

Abstract

This paper presents the results of an experimental investigation on the deformation and cracking behaviors of ring-shaped granite specimens. Diametrical compression tests were conducted on ring-shaped granite specimens with inclusion and those without inclusion for comparison. The inclusion materials were of different strengths, stiffness, and sizes. Strain gauges (SGs) were amounted at the boundary of the hole to trace the strain evolutions, and digital image correlation (DIC) technique was used to identify the crack initiation and propagation process. The results indicated that the inclusion has a positive effect on the enhancement of the carrying capacity. The maximum carrying capacity of the specimen with low-strength inclusion decreases with increasing the inclusion diameter, while it first decreases and then increases when the inclusion diameter increases from 10 to 20 mm for the high-strength infilled specimens. The results of the strain evolutions analyzed by the SGs and DIC methods indicate that a lager hole diameter and a lower inclusion strength lead to a more intensive strain concentration around the hole. Due to the mismatch in the deformation at the rock–cement mortar interface, serious strain concentrations are induced, and hence leading to three types of failure, i.e., debonding between the interface, tensile crack in the granite, and tensile crack in the inclusion material.