The Excavation Damage Zone Of A Subway Tunnel Considering Stress Release

The excavation damaged/disturbed zone (EDZ) is significantly important for determining the loosening load of rock mass surrounding tunnel. While the main search was focused on the hard rock in the past, this paper presents a study on the soft ground of the longest subway tunnel constructed by subsurface excavation in China. Based on the damage constitutive laws, the method of numerical analysis was funded by finite element, which was validated by comparing with the laboratory tests. Some results can be concluded by numerical analysis. The EDZ of rock mass is an approximate circle around tunnel for the isotropic initial stress of the ground, and it will initiate when the ratio of stress release is more than 0.5. Besides, the EDZ would suddenly increase as the ratio of stress release is over 0.9. There will be an obvious stress concentration and deformation gradient in the EZD.