Influence of weak inclusions on the fracturing and fractal behavior of a jointed rock mass containing an opening: Experimental and numerical studies

Abstract To gain a better understanding of the interaction between weak inclusions and jointed rock masses, a conceptual model containing a joint set and an opening is prepared, and cases involving unfilled and filled openings are considered. The influence of weak inclusions on the fracturing and fractal behavior of these models is investigated by using laboratory experiments, the rock failure process analysis (RFPA) code and the fractal geometry. An overhanging beam model is proposed to explain the initiation mechanism of tensile cracks around the unfilled and filled openings. The RFPA simulations provide deep and quantitative insight into the fracturing behavior. The coalescence patterns of the surrounding rock mass obtained from physical and numerical tests are in reasonable agreement, and can be classified into two categories: shearing along the joint set and cutting through the rock bridges. The inclusion with a low strength exerts little influence on the failure pattern but has an appreciable reduction in the stress values and an appreciable increment in the mechanical properties. The crack coalescence exhibits fractal properties, and there are good correlations between the fractal dimension and mechanical properties of these jointed rock specimens containing unfilled and filled openings.