This study investigates the mechanical properties and stability classification of surrounding rock masses in deep coal mine roadways using the Guojiawan Coal Mine in Shanxi Province, China, as a case study. This study synthesized multiple parameters from laboratory testing, in situ stress measurements, and the Stability Index (SI) method to quantify stability by lithology type in a heterogeneous deep mining system. The study developed a procedure that involved collecting rock samples from the 51206 and 51207 return ventilation roadways that represented silty mudstone, fine sandstone, coarse sandstone, and coal, and utilizing the GB/T 23561.1-2009 specifications, the samples were tested using uniaxial compressive, Brazilian splitting, and triaxial compressive testing. Statistical analysis (n ≥ 3 for each test type) of the rock samples showed that coarse sandstone had the highest uniaxial compressive strength (UCS) (52.86 ± 1.85 MPa) and elastic modulus (13.11 ± 0.75 GPa), and coal had the lowest (UCS: 20.43 ± 2.15 MPa; E: 2.36 ± 0.22 GPa). In situ stress conditions were low to moderate (σH = 9.99 MPa at 270 m); however, localized stress concentrations were present next to lithologies. The SI classified coarse sandstone as stable (e = 0.30-0.44), silty mudstone as stable to moderately stable (e = 0.47-0.73), and coal seams as moderately stable (e = 0.31-0.46). The Guojiawan Coal Mine case study illustrates how using laboratory-derived parameters together with site-specific stress conditions can provide results to optimize roadway support design in deep and geologically heterogeneous mining environments, offering a transferable framework for similar underground excavations.
Jahid et al. (Tue,) studied this question.