Excavation Design for the Novel Vertical Cutter Mining (VCM) Method: Effects of Shaft Spacing on Stress and Strain Distribution *F. Tavanaei1, A. Ahmadihosseini2, F. Hassani1, A. Mortazavi3, M. Fadaei Kermani1 1 Department of Mining and Materials Engineering, McGill University, Montreal (*Presenting author: fatemeh.tavanaeisereshgi@mail.mcgill.ca) 2Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, Canada 3School of Mining & Geosciences, Nazarbayev University, Kazakhstan ABSTRACT Vertical Cutter Mining (VCM) has received growing attention in the mining industry due to its functionality and operational advantages. However, as a relatively novel excavation method, its design principles and geomechanical implications still require systematic investigation. This study examines the mechanical interaction between two adjacent vertical shafts under varying spacing conditions through numerical analysis conducted in two scenarios, distinguished by whether the first shaft is backfilled or left unfilled. The objective was to quantify how the excavation of a second shaft alters the stress and strain fields surrounding the first shaft and to determine the spacing at which interaction effects become negligible. Across both scenarios, the introduction of a second shaft consistently elevated the stress and strain responses in the surrounding rock mass, demonstrating that closely spaced excavations generate overlapping stress‑influence zones. The most pronounced effects occurred at the smallest spacing (S1), where von Mises and principal stresses increased to roughly 1.5 times those observed in the single‑shaft configuration. This amplification clearly indicates significant stress superposition and highlights the importance of spacing optimization in VCM design. As spacing increased, these amplified responses diminished rapidly, with the widest spacing (S3) producing stress and strain distributions that closely matched the results of single‑shaft baseline. Both cases showed similar overall trends, but the amount of strain increase differed, indicating that the results are sensitive to boundary conditions or material assumptions. The results demonstrate that shaft spacing is a critical design parameter governing excavation‑induced stress redistribution. Ensuring adequate separation between shafts can substantially reduce interaction effects, improve stability, and minimize deformation in multi‑shaft systems. These findings provide a quantitative basis for optimizing shaft layout in similar geological settings and contribute to improved design guidelines for underground infrastructure. KEYWORDS Vertical Cutter Mining (VCM), shaft interaction, excavation spacing, numerical modelling, stress redistribution.
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