The Mechanical Analysis and Interpretation of the EDZ Formation around Deep Tunnels within Massive Rockmasses Using a Hybrid Finite-Discrete Element Approach: The case of the AECL URL Test Tunnel

The construction of an underground opening leads to changes in the in situ stress regime surrounding the excavation. The opening influences the rockmass due to the redistribution of the stresses and results in the disturbance of the surrounding ground. At great depths, massive to relatively slightly or moderately fractured rockmasses are usually encountered and under high stresses they are more likely to behave in a brittle manner during an excavation. While constitutive models have been developed and proposed for the numerical simulation of such excavations using continuum mechanics, this brittle response cannot be simulated accurately enough since the material behaviour is governed by fracture initiation and propagation. On the contrary, discontinuum approaches are more suitable in such cases. For the purposes of this paper, the brittle behaviour of hard, massive rockmasses and the associated spalling failure mechanisms were simulated by employing a Finite Element Method/Discrete Element Method (FDEM) approach using the Irazu software. The generated numerical model was utilized in order to replicate field conditions based on the observations at the AECL-URL Test Tunnel located in Pinawa, Manitoba, Canada. The model results are compared to field observation data in order to explicitly demonstrate the suitability of the method.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author