Document Type : Original Research Paper

Authors

• Mahan Amirkhani ¹
• Mojtaba Bahaaddini ¹
• Alireza Kargar ¹
• Amin Hekmatnejad ²

¹ School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran

² Departamento de Ingeniería de Minería, Escuela de Ingeniería, Pontificia Universidad Cat´olica de Chile, Chile

Abstract

The stability of tunnels and underground openings in jointed rock masses is significantly influenced by the development an Excavation Damage Zone (EDZ), where discontinuities alter stress distribution and the fractured propagation zone. In previous studies on EDZ, rock mass is commonly considered as a continuum medium, while the joint system can dictate the size of EDZ. This study aims to investigate the EDZ around a tunnel excavated in a jointed rock mass using the Discrete Fracture Network (DFN) and Discrete Element Method (DEM). Three DFN models with different fracture intensities of 0.5, 1.0, and 1.5 m²/m³ were simulated to explore the progressive failure mechanisms and damage evolution around a tunnel. The DFN models were then imported into the DEM code. The area of the plastic zone was considered a representative measure of the EDZ. The influence of joint mechanical properties, including cohesion, friction angle, normal, and shear stiffnesses, was investigated. A dimensionless sensitivity analysis was conducted to evaluate and compare the influence of each parameter. The results show that the joint friction angle is the most influential parameter in all fracture intensities. These insights provide a more precise understanding of joint behaviour and its impact on tunnel stability in different geological settings.

Keywords

• Excavation Damage Zone
• Jointed Rock Mass
• Discrete Fracture Network
• Fracture intensity
• Discrete Element Method

Main Subjects

• Rock Mechanics