Experimental study on mechanical behavior, AE response and energy evolution of fissure-filled sandstone from mine roadway under conventional triaxial compression

Engineering reliability exhibit sophistication and unpredictability for mining from all the regions, largely due to the random combinatorial morphology of natural discontinuities associated with the ubiquitous fissures in the rock formation. This study determined the effects of intersecting fissure angle (none, 0°, 30°, 45°, 60°, and 90°) and confining pressures (4, 8, 12, and 16 MPa) on its mechanical behaviors by triaxial compression tests targeting in fissure-filled sandstones from Lu-Xi coal in Shandong Province, China. Mechanical and AE results indicated that fissure inclination and confining pressure were the origin of the variation in the mechanical behaviors and AE parameters of the sandstone specimens. With increase of pre-existing flaw angle, the peak strength, elastic modulus, peak strain and AE counts presented a U-shape trend. With rise of confining pressure, these parameters displayed a linearly upward trend. However, no significant correlation was found for the Poisson’s ratio. Besides, energy analysis showed that the energy values of the specimens at the peak stress reflected well the variation of the mechanical parameters of the fractured sandstone. This study provided implications for stability of surrounding rock in mine roadway.