Quantitative morphology and stress-scalable AE early-warning of shear failure in twin tunnels integrated experimental and DEM analysis

Key Points

• To investigate shear failure sequences in twin tunnels and develop a stress-scalable early warning system.
• Conduct experimental analysis to observe shear failure sequence in twin circular tunnels.
• Apply discrete element method (DEM) analysis for quantitative morphology assessment.
• Establish an acoustic emission framework for early warning signals.
• Identified a four-stage shear failure sequence in twin tunnels.
• Normal stress was found to increase failure dip angles by sixfold and fracture roughness by 27%.
• Acoustic emission framework provides 30-50 seconds advance notice for potential failures.