The Effect of Jointing in Massive Highly Interlocked Rockmasses Under High Stresses by Using a FDEM Approach

Abstract

In deep underground mines and deep infrastructure tunnels, spalling and strain bursting are among the most common failure mechanisms observed and reported in massive rockmasses under high stresses. Therefore, the need to be able to estimate such conditions and counter them with an economic and effective design is rising. Part of the common practice is the use of computer packages involving numerical methods based on continuum approaches. However, the failure mechanisms involved and the rockmass response observed are often difficult to capture by employing such methods and usually discontinuum approaches are better suited for this task. Additionally, discrete structures observed within the rockmass in situ, such as joints and other discontinuities, can be explicitly incorporated into the numerical model in order to investigate their effect on the overall rockmass response during an underground excavation and adjust the design if necessary. In this study, the presence of joints and their effect on the response of a hard rockmass under a high stress regime during an excavation is examined by employing a FDEM (Finite-Discrete Element Method) approach. The setup of the numerical model is based on the URL (Underground Research Laboratory) Test Tunnel located in Pinawa, Manitoba, Canada and a Discrete Fracture Network (DFN) model is implemented in order to simulate the impact of joints on brittle failure. Numerical results show that the presence of joints increases the intensity and evolution of the damage during the excavation.