Fractures and Acoustic Emission Features of Non-persistent Jointed Rocks Subjected to Freeze-Thaw-Compression Load: Experimental Insights

Rock mass containing central locked segments is susceptible to freeze-thaw weathering and could result in rock instability and even serious geological hazards. This work conducts uniaxial compression and acoustic emission synchronization tests to experimentally investigate the rock bridge deformation and failure characteristics of central locked samples drilled from plateaus in China. The influences of freeze-thaw cycles and rock bridge angle on the fracturing and acoustic emission pattern were characterized. Results show that the physical and mechanical parameters deteriorate in varying degrees with the increase of freeze-thaw cycles. The compression stress curves display as fluctuation trend and multiple stress drops, indicating that the rock bridge improves the plastic properties of samples. The points of stress drops are in good agreement with sudden increment of acoustic emission count curve. The acoustic emission count and released acoustic emission energy decrease with the increase of freeze-thaw cycles. The damage model established based on acoustic emission parameters reflects the process of crack propagation and coalescence of central locked sample subjected to freeze-thaw cycles during uniaxial compression. Damage variable evolution rate decreases with increasing of freeze-thaw cycles. The damage evolution rate and the associated crack growth rate is the smallest for a rock with bridge angle of 30 degrees.