Stress state effect on the mechanical behavior of coals under true triaxial compression conditions

Experimental results of deformation and fracture of coals under true triaxial compression at various stress states as defined by the Nadai-Lode parameter obtained using the original true triaxial loading (TTAL) apparatus developed at the Institute for Physics of Mining Processes NAS Ukraine are presented. In particular, alteration in the mechanical performance of coals in different stress states, effect of the stress state on methane emission kinetics from coals at various temperature regimes and effect of moisture content on the mechanical performance of coals in different stress states are discussed.