2D numerical simulation on excavation damaged zone induced by dynamic stress redistribution

• Dynamic stress redistribution resulted from transient unloading due to excavation is considered.
• The 2D numerical simulation on excavation damaged zone induced by dynamic stress redistribution is conducted.
• Damage zone induced by transient unloading is only in the 20% diameter vicinity of excavation perimeter.

The formation of an excavation damaged zone (EDZ) around an opening in a deep rock mass is associated with the dynamic stress redistribution that starts from transient release of high in situ stress to the final quasi-static stress state after the excavation. This study applies a theoretical analysis of stress redistribution due to transient unloading in surrounding rock under hydrostatic stress field, and develops a numerical elastodynamics model for finite element analysis. Coupling the theoretical and the numerical solutions, a general damage model for heterogeneous rock mass is proposed by taking the dynamic stress redistribution due to excavation into account. Finally, the dynamic stress redistribution, as well as the induced damage zone around the excavation under different lateral pressure coefficients is numerically simulated. The numerical result indicates that, the stress wave induced by the transient unloading will initially cause the damage only in the 1/3 radius vicinity of excavation perimeter. The damage zone may then develop further under the constant quasi-static far-field stress. Therefore, the EDZ development during deep excavation is closely dependent on in situ stress, rock strength and excavation method.