Abstract
A major task in mines and even more in underground repositories for nuclear waste is to investigate crack formation for evaluation of rock mass integrity of the host rock. Therefore, in situ acoustic emission (AE) monitoring are carried out in mines as part of geomechanical investigations regarding the stability of underground cavities and the integrity of the rock mass. In this work, the capability of in situ AE monitoring in the context of structural health monitoring (SHM) in mines and in various geological settings will be reported. SHM pointed out, that the AE network is able to monitoring AE activity in rock with a volume up to 10 6 cubicmeter and distances up to 200 m (e.g., 100 m × 100 m × 100 m) in the frequency range of 1 kHz to 150 kHz. Very small AE events with source size in approximately centimeter to millimeter scale are detected. The results show that AE activity monitors rock deformation in geological boundaries due to convergence of the rock. In addition, high AE activity occurs in zones of dilatancy stress in homogenous rock. In conclusion in situ AE monitoring is a useful tool to observe instabilities in rock long before any damage becomes visible.
Highlights
For the safe use of various structures, a regular inspection is required
This article summarizes the capability of in situ acoustic emission (AE) monitoring in the context of structural health monitoring (SHM) based on the results of monitoring projects in mines
The in situ AE method is capable of detecting microcracking, in high resolution and sensitivity, which is caused by very small deformation processes at high deviatoric stresses
Summary
For the safe use of various structures, a regular inspection is required. For critical infrastructures in particular, like aircraft, pressure vessels, and bridges as well as underground structures like mines, monitoring of their conditions is necessary. SHM is known as the continuous or periodical and automated method for monitoring and evaluating the condition of a monitoring subject. It is part of condition monitoring according to the International Organization for Standardization (ISO) 17359 [1]. Vibration analysis is the most commonly applied method, and the analysis techniques have advanced greatly over the historic observation that if a machine is vibrating more than normal it is likely to be faulty These kinds of measurements are used as predictive maintenance (PdM), which are performed to determine the condition of equipment in order to predict when maintenance should be done. In order to identify wear particles or chemical contaminants, it is common to apply lubricant measurements, while the use of thermography to identify temperature anomalies is increasing
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