Research on the Surrounding Rock Damage of Deep Hard Rock Tunnels Caused by Bottom excavation

摘要

The damage features of surrounding rock in the process of bottom excavation in deep hard rock tunnel were investigated, combining with the actual tunnel data of Jinping II Hydropower Station and using numerical simulation approach. The evolution mechanism of microfractures initiation, growth and expansion in deep intact rock mass was performed. It's shown that the fractures caused by bottom excavation develop to deeper surrounding rock due to stress adjustment, and the zone that have been supported also has some damage. The research results provide important references to understand the damage features of surrounding rock in deep hard rock under high geostress.