Realistic Simulation of Progressive Brittle Rock Failure Near Excavation Boundary

Abstract

Over the last two decades, the importance of rock material heterogeneity on rock strength has been well recognized. Because of the material heterogeneity, local stress concentration is generated from which failure is initiated. In addition to material heterogeneity, geometrical heterogeneity in the form of boundary irregularity must be properly considered when assessing rock strength. This is particularly important for modeling brittle rock failure near excavation boundary. As the tunnel face advance, the maximum tangential stress at the wall increases gradually. Any surface geometrical heterogeneity will increase the stress, which in turn will affect the spalling failure process. It is demonstrated in the present study that when the excavation boundary geometrical heterogeneity is properly considered, in-situ rock strength can be properly interpreted and progressive rock failure process can be realistically simulated using a simple Mohr-Coulomb model for brittle rocks.