Investigation of geomechanical properties of coal and surrounding rock in TTK Kozlu and Üzülmez institutions

The Zonguldak Hard Coal Basin is the only region in Turkey where hard coal is produced. Production is carried out in underground mines operated by the Türkiye Taşkömürü Kurumu (TTK). In this study, samples were prepared from different coal and rock blocks collected from production zones, ventilation drifts, and development galleries in the Kozlu and Üzülmez Mines, which are part of the TTK. Various rock mechanics tests were conducted in relevant laboratories, including uniaxial compressive strength (UCS), point load index (PLI), tensile strength, ultrasonic P-wave velocity (UPV), Leeb hardness, density, and water absorption tests. The aim was to examine the geomechanical properties of coal and surrounding rocks. When the rock blocks were brought to the laboratory, initial Leeb hardness tests were performed on rough and smooth surfaces without causing sample disturbance. Ultrasonic P- wave velocity values were determined for cores with a proper shape, and uniaxial compressive strength tests were conducted on NX-diameter cores prepared at 1.5, 2, and 2.5 length-to-diameter (L/D) ratios. NX-diameter cylindrical samples prepared from the rock blocks were also subjected to tensile strength and point load strength tests. Additionally, taking into account the test results, a excavability estimate was made for coal and surrounding rocks.