Self-Excited Acoustical Measurement System for Rock Mass Stress Mapping

Area of Science:

• Geophysics
• Acoustics
• Materials Science

Background:

• Nondestructive testing (NDT) is crucial for assessing structural integrity in mining.
• Existing methods for monitoring rock mass stresses can be limited in scope and application.
• The elastoacoustical effect offers a potential mechanism for stress detection.

Purpose of the Study:

• To present a preliminary study of a self-excited acoustical system (SAS) for NDT applications.
• To examine the feasibility of using SAS for evaluating stresses in mine excavations.
• To develop a method for creating actual stress maps in mine ceilings.

Main Methods:

• Utilized the elastoacoustical effect as the principle of operation for the SAS.
• Performed numerical analysis of excavation considering stress factors.
• Developed an equivalent model of a two-degree-of-freedom system with delay.
• Conducted tests on anchorages in laboratory and Wieliczka Salt Mine conditions.

Main Results:

• Established a relationship between the self-excited system's frequency and the stress level in the rock mass.
• Quantified this relationship using the elastoacoustic coefficient.
• Demonstrated the creation of actual stress maps in mine excavation ceilings.
• Validated the SAS for monitoring rock mass stress states.

Conclusions:

• The self-excited acoustical system (SAS) is a viable tool for nondestructive testing in mining environments.
• The developed method allows for effective monitoring of stress conditions in rock masses.
• SAS technology shows promise for enhancing safety and operational efficiency in excavations.