Experimental and Numerical Studies on Interaction Mechanism between Joints and a Hole in Rock-like Materials under Uniaxial Compression

Abstract

To investigate the influence of joints on the stability of underground opening, uniaxial compression tests and FE analyses based on a microplane damage model for rocks has been conducted for rock-like models with a circular hole and a set of non-persistent joints. It was found that the peak strength and Young’s modulus decrease with the increase in joint continuity factor k, and variation of them with joint inclination angle β are W or V-shaped curves with the minima and maxima at β = 30° and 90°, respectively. The failure modes of the specimens and the collapse modes of the hole can be related to crack coalescence between the hole and the joints or matrix. Numerical simulation can reproduce the main features of macroscopic mechanical behavior and explain the anisotropic damage mechanism. The strong interaction between the hole and the nearest joint was revealed. During the elastic stage, stress concentration around the hole will be altered by the presence of the joints, and the effect may be strengthened with the increase in k. At the peak strength, the current stress concentration areas will be transferred from the hole surface to the interior due to stress loosening in damage localization bands/zones, and a higher hoop stress concentration factor may lead to lower strength.

Keywords

• jointed rock masses with a hole
• joint persistence
• joint orientation
• microplane model
• FE modeling