Characteristics and Precursor of Static and Dynamic Triggered Rockburst: Insight from Multifractal

To probe the difference between static-driven and dynamically triggered rockbursts, three types (static-driven rockburst, SDR; pulse-disturbance rockburst, PUDR; period-disturbance rockburst, PEDR) of true triaxial unloading rockburst tests were carried out on marble. The rockburst characteristics were compared and analyzed through five distinct aspects (stress–strain curve, energy consumption, failure mode, ejection features and acoustic emission (AE) multifractal characteristics). The results indicate that the rockburst stress values of the PUDR, the SDR and the PEDR decrease successively, which indicates that the PEDR and the PUDR are the most prone and the most difficult to occur, respectively. Additionally, the stress–strain curve (after yielding) data indicates that the PUDR, the SDR and the PEDR are characterized by a yield platform, strain hardening and strain softening, respectively. Moreover, the rockburst intensities of the PUDR, the SDR and the PEDR also decrease successively. Furthermore, the initial increase and the subsequent decrease of the AE multifractal parameter (∆ f ( α )) can be used as the precursor for the different types of rockbursts. However, the early warning time is related to the intensity of the rockburst, which implies that greater intensity values lead to a shorter early warning time. In general, the ∆ f ( α ) parameter and the stress drop can be used for long-term monitoring and short-impending prediction of rockburst, respectively.