Mechanical response of tunnel surrounding rock under blasting disturbance with different stress conditions based on acoustic emission and digital image correlation

Deeply buried tunnels are highly susceptible to dynamic ground pressure disasters, such as roof collapse and rockburst caused by blasting disturbances, posing significant threats to the underground engineering safety. To clarify the dynamic response characteristics of tunnel surrounding rock under different boundary stress conditions, this study integrates theoretical analysis with laboratory experiments using acoustic emission (AE) monitoring and Digital Image Correlation (DIC) techniques. The combined AE–DIC approach enables simultaneous capture of internal fracture activity and surface deformation. Results show that blasting disturbances accelerate the rock failure. Under uniaxial loading, strain growth rate and the proportion of AE events increase as axial stress approaches peak strength. Under biaxial loading, as the lateral pressure coefficient (k) increases from 0.45 to 0.7, the strain-affected zone resulting by blasting becomes progressively narrower. The presence of confining pressure leads to a more disordered and complex spatial distribution of AE events and a marked increase in tensile cracking. These findings enhance the understanding of dynamic failure mechanisms in deep tunnel environments and provide engineering geological insights for optimizing excavation stability and disaster prevention strategies.