Experimental investigation on the mixed-mode fracture behavior of rock-like material with bedding plane

Abstract

To investigate the combined effects of bedding plane angle and notch angle on the mixed-mode fracture behavior of rock-like material, three-point bending tests of semi-circular bend (SCB) rock-like specimens with two relative locations between bedding plane and notch were first conducted accompanied by acoustic emission (AE) tests. The fracture surface characteristics of SCB rock-like specimens were then scanned and analyzed. The experimental results revealed that both the bedding plane angle and notch angle showed strong influences on the fracture behavior of rock-like material. Under each bedding plane angle, most of the fracture load continuously increased with the increasing notch angle. Under each notch angle, the fracture load continuously decreased with the increasing bedding plane angle. The fracture load of SCB rock-like specimens when bedding plane pro-dip to the notch was larger than that when bedding plane anti-dip to the notch. With the increasing bedding plane angle, most of the values of mode I, mode II and effective fracture toughness continuously decreased. With the increasing bedding plane angle, the fracture modes of SCB rock-like specimens transformed to bedding plane dominant fracture. The fracture surface properties are closely related with the fracture mode of SCB rock-like specimens. When bedding plane anti-dip to the notch, joint roughness coefficient (JRC) values almost linearly decreased with the increasing bedding plane angle. With different bedding plane angles and notch angles, the relationships between fracture load and accumulated AE energy could be well described by the linear function.