Introduction

Natural engineering geomaterials, such as rocks, can contain various discontinuities and defects of different sizes, including pores, joints, faults, bedding planes, cracks, fissures, cavities, and notches (Fig. 1.1). The growth of cracks from existing notches or joints is a significant concern, as it can lead to instability in engineering projects. When a rock mass containing non-persistent joints is loaded, the joint tips often act as micro-instability foci, from which cracks emerge as slipping tendencies become activated. This process can ultimately compromise the stability of the engineering project (Haeri et al., 2013a; Haeri, 2015a; Sarfarazi & Haeri, 2016a; Sarfarazi & Schubert, 2017). These investigations reveal the type of cracks, their patterns, and how they are interconnected. Figure 1.2 illustrates the distribution of intersecting non-persistent joints (notches). This figure demonstrates how the slip-prone wedge is formed from these non-persistent joints.