Notched Rock Pillar Uniaxial Test Failure Modes Based on Laboratory Test and Numerical Simulation

Pillars are pillars placed in a mine to support the overburden material to prevent it from caving between the adjacent underground workings. Evidence shows that pillar failure is becoming more and more common and critical with the progressive increase in ambient stresses when mine depths are increased. This failure process can be considered as a progressive one because it is characterized by crack initiation and propagation, disturbance of local fields, formation of local failures, and opening of the fracture plane. These microprocesses result in macro-pillar failure and the associated loss of load-bearing capability. The pillar system of fractured rock mass is a complex mechanical system member because the rock mass is a geological system being expressed as a system of blocks belonging to one or more types of rock mass with cracks of various signs, which means that the strength and deformation mechanism of a pillar depend on defects and discontinuities in the pillar and their definition. While many studies have been done to determine the loading and failure properties of pillars, it is still challenging to predict the stability of pillars or a pillar and roof support system considering many factors, such as in situ stress and geology (Rezaei et al., 2023; Sarfarazi et al., 2021a, 2021b, 2021c). Rezaei et al. (2024) investigated the effect of pillar width and the room’s height on the acoustic emission phenomena of the crack evolution. Experiment results indicated that two failure modes were identified for the model. Identifying crack growth in these models is crucial. The process begins with the formation of two tensile cracks originating from the corners of the room. These cracks, which are smooth and polished, propagate at an angle to the load axis, ultimately connecting the splitting crack to the specimen boundary.