An experimental investigation on the failure behavior of sandstone with filled fissure under triaxial multilevel cyclic loading

Roadways are common in infrastructure of the underground engineering. The surrounding rocks of these roadways are often allowed to work with flaws and are subjected to cyclic loading with variable magnitude. However, the existing experimental data regarding their behavior are insufficient. This study investigated how confining pressure and the inclination of pre-existing fissures affect the mechanical properties and failure mechanisms of sandstones from the Lu-Xi coal roadway in Shandong Province. Utilizing triaxial cyclic experiments along with real-time acoustic emission (AE) monitoring, the findings were presented with respect to the evolution of strength as well as deformation behaviors, failure modes, and AE event frequency. Finally, the impact of the above two factors on damage mechanisms of preflawed sandstone materials were detailed discussed in terms of the fracture mechanics. This study highlights the importance the buried depth and flaws for the rock engineering and the sensitivity of sandstone's mechanical responses in changes in the lateral restriction and fissure angle.