Elasto-Plastic Semi-Analytical Solution for Deep Circular Tunnels Considering Excavation Induced Damage in Surrounding Rock Mass

ABSTRACT: The stability of deep circular tunnels is significantly influenced by stress relaxation and associated damage in the surrounding rock mass. Traditional analytical and numerical models often assume a constant or simplified damage factor, which may not accurately capture the continuous nature of damage propagation. This study presents a semi-analytical elastoplastic solution that incorporates a stress-dependent damage factor into the Generalized Hoek-Brown failure criterion. The proposed model defines the shear strength of the rock mass as a function of stress relaxation and damage attenuation, allowing for a more realistic representation of post-excavation behavior. The model's predictions are validated against finite element simulations, demonstrating strong agreement in stress distribution and displacement trends. The findings highlight the importance of accounting for damage attenuation when assessing tunnel stability, offering a more refined approach for tunnel design under high in-situ stress conditions.