Developing of a new in-situ monitoring system to determine the time-dependent mechanical behaviours of underground mine pillars: Electrical measurement method

In the excavation environments of underground mining works, the balance of the original primary land stresses is disturbed and deformations occur. The original primary land stresses, which were disturbed by the fortification works, reach the secondary stress magnitudes by coming back into balance. Although stability is ensured by the fortification works in the excavation openings, the production works carried out in the nearby areas may affect this new balance again. The monitoring of the stress and deformation changes around the underground openings is made with measuring devices placed in the holes drilled in the side wall around the opening (gallery, tunnel, etc.). These gauges generally use hydraulic and/or electronic systems. Electrical Resistance Measurement System (ERMS) as an alternative to existing measurement systems was developed in this study and its first applications were carried out in TKİ-GLİ-Ömerler Underground Mine A6 production panel material gallery and A7 preparation panel transportation gallery. With this method, electrical resistance (Ω) changes in rock material around the opening exposed to dynamic loadings formed based on longwall production were measured from the measurements taken from five measurement stations established in A6 panel and fracture behaviors in heel rock material were examined. In addition, electrical resistance (Ω) behaviors explaining failures in coal material based on pressure created by hydraulic jack established in three application pockets prepared in A7 panel were determined. The measurement system (ERMS) presented in this study can be a new measurement method that can be used in determining failures and stabilities in rock materials in mining operations.