Deterioration Mechanism and Health Diagnosis Methods of Deep Anchoring Structures

Area of Science:

• Geotechnical Engineering
• Materials Science
• Corrosion Science

Background:

• Deep underground mining increases corrosion risks for rock bolts, a critical safety component in roadways.
• Anchorage failure due to corrosion is a major concern for deep roadway stability.

Purpose of the Study:

• To investigate failure mechanisms of anchoring systems under coupled multi-physical fields.
• To develop a health diagnosis system for deep underground anchoring structures.

Main Methods:

• Numerical simulations of multi-field corrosion processes.
• Ultrasonic nondestructive testing (NDT) integrated with numerical modeling.
• Analysis of temperature's influence on corrosion rate and current density.

Main Results:

• Elevated temperatures accelerate bolt corrosion by negatively shifting equilibrium potential and increasing reaction rates.
• Ultrasonic testing reveals defect characteristics: frequency multiplication for minor defects, amplitude reduction and wave lag for larger defects.
• All characteristic indices for ultrasonic testing increase monotonically with defect size.

Conclusions:

• A spatial complementary mechanism for corrosion defects was identified.
• A four-level grading diagnosis standard and a "bottom-lateral" detection scheme were proposed.
• The developed model provides a quantitative basis for assessing anchoring structures in high-temperature deep underground environments.