Describing quality of rocks around underground headings: Endoscopic observations of fractures

The paper presents the results of endoscopic research in the fracture zone of rock layers in the premises of underground headings. The evaluation of roof rocks carried out using a visual camera allows for the determination of their quality as it is equally effective method to the other popular ways of describing rock quality. The results obtained allowed for the proper estimation of fracture zone around the underground heading in selected coal mines.