Numerical analysis of damage and disturbance effect of surrounding rocks induced by deep tunnel blast excavation

Abstract

The damage and failure analysis of deep rock mass subjected to blasting under different crustal stress conditions is still insufficient at present. To explore the damage and failure law of surrounding rocks of deep tunnel during blasting excavation, based on the finite element software ANSYS/LS-DYNA, the Riedel-Hiermaier-Thoma constitutive model is adopted to carry out numerical analysis on the influencing factors of tunnel blasting effect and surrounding rock disturbance range under different crustal stress environments. The results show that the cross-section damage degree of the bidirectional isobaric tunnel is negatively correlated with the geostress level. With the increasing geostress, the damage of the tunnel floor is more significantly suppressed by geostress. The surrounding rocks at the waist of the tunnel is prominently disturbed by blasting, and its stress and vibration velocity increase significantly with the increasing lateral pressure coefficient, and the vibration velocity increases by more than 40%, much higher than that of the top surrounding rocks. Under the vertical stress of 20 MPa, the amplitudes of stress and vibration velocity at the waist measuring point increase slowly with the increasing lateral pressure coefficient. When the vertical stress rises to 60 MPa, the lateral pressure coefficient has a great influence on the disturbance of surrounding rocks. The relevant conclusions obtained are of important guiding significance for actual engineering construction, and are of certain reference value for monitoring the stability of tunnel surrounding rocks and optimizing support parameters.

Keywords

• deep tunnel
• blast excavation
• surrounding rock
• disturbance and damage
• numerical simulation