Modeling of Fracture and Damage in Rock by the Bonded-Particle Model

Abstract

Since potential disturbance of a near-field host rock could adversely affect the stability of underground openings and could possibly change the properties of rock mass, it is very important to evaluate deformation and fracturing characteristics of rock. In this study, PFC 2D modeling as well as laboratory experiments were carried out to study characteristics of deformation and fracturing of rocks under uniaxial and triaxial compressive conditions. Laboratory experiments include stress-strain measurements and acoustic emission measurements to carry out the moving point regression analysis. Damage thresholds showed linear relationships with confining pressures. In addition, the feasibility of the application of the bonded-particle model to reproduce mechanical behaviors of rocks was explored by comparing model behaviors to results from experiments at different confining pressures. The model could exhibit macroscopic behaviors such as strain softening, dilation and fracture that arise from extensive microcracking throughout a bonded assembly. However, axial stress increments with increasing confining pressures were much smaller than those from experiments.

Implementation of Particle-scale Rotation in the 3-D Lattice Solid Model

“…5, left). However when k 2 >1.25 abrupt failure moods are produced, with significant high macroscopic strength (40 to 75), which is similar with Chang's results (CHANG et al, 2002). Figure 6 shows with the increase of ratio k 2 , macroscopic strength increase, and the shear bands seem to be wider.…”

“…CHANG et al (2002) suggested that another ratio k 2 ¼ F s0 =F r0 may effect the fracture mode, they found that larger k 2 generate brittle failure in uniaxial compression tests. According to rock experiments (ATTEWELL et al, 1976), compressive strength is generally ten times of tensile strength, and shear strength (cohesion) is nearly one to two times of tensile strength.…”

“…Particle-based models have been extensively used in recent years to model a diverse range of processes from rock failure (HUZZARD et al, 2000(HUZZARD et al, , 2002CHANG et al, 2002), particle flow (LANGSTON et al, 2004), mining (PROCHAZKA, 2004), to tectonic processes (HU et al, 2004). These models typically deal with a system which can be considered as an assemblage of discrete particles interacting with one another.…”

“…These kinds of models are suitable to model motions of powder (SHENG et al, 2004) and behaviors of particulate materials (SITHARAM, 2000). Another kind of model permits the neighboring particles to be linked together by elastic bonds or molecular bonds or springs (e.g., MORA et al, 1993;CHANG et al, 2002;HUZZARD et al, 2000HUZZARD et al, , 2002, which can transfer elastic forces, both attractive or repulsive, when the bond is pulled or pushed. Bonds break if the distance between the particle pair exceeds certain threshold breaking distance.…”

Modeling Wing Crack Extension: Implications for the Ingredients of Discrete Element Model

“…For the bonded models, there are different varieties according to interactions being transmitted between bonded particles: Only radial interaction is allowed PLACE, 1993, 1994;MORA et al, 2000;TOOMEY and BEAN, 2000), or only normal and shear forces are present (SCOTT, 1996;CHANG et al, 2002;HAZZARD and YOUNG, 2000), or normal, shear forces and torques are transmitted (WANG et al, 2000(WANG et al, , 2006ODA, 1998, 2000;POTYONDY and CUNDALL, 2004).…”