Research on the Excavation Damage Characteristics in Tunnel Surrounding Rock Based on Damage Mechanics

Research purposes: The excavation damage of surrounding rock will inevitably affect the mechanical properties and stability of surrounding rock. When it is not controlled properly, failure or collapse accident may occur. Therefore, we must master the characteristics and evolution mechanism of surrounding rock damage, so as to provide basis for surrounding rock damage control and support design. Based on microseismic monitoring results, the damage characteristics of surrounding rock caused by tunnel excavation is revealed. The expression of damage zone is deduced by using strain softening model and damage mechanics theory without considering structural stress, which is compared with the measured results. The influencing factors of damage characteristics are further analyzed. Research conclusions: (1) The theoretical prediction results are in good agreement with the measured data, and when the worse the surrounding rock is, the smaller the error is. (2) The radius of surrounding rock damage zone increases with the increase of brittleness coefficient λ/E, and decreases with the decrease of surrounding rock cohesion c and internal friction angle φ. The radius of high damage zone of surrounding rock increases with the increase of ultimate damage parameter Dcr with the growth rate faster. (3) The ultimate damage parameter Dcr and brittleness coefficient λ/E are not only related to the parameters of surrounding rock itself, but also related to the support means. (4) The research results can provide reference for the prediction and safety control of excavation damage of surrounding rock. © 2023 Editorial Department of Journal of Railway Engineering Society. All rights reserved.