Mechanical Behaviour of Rock Samples with Burst Liability Under Different Pre-Cycling Thresholds

To study the influence of the main roof period pressure on the instability mechanism of rock pillars with burst liability, the composite loading mode of "pre-cycling loading + continuous loading with a constant rate" was used to conduct compression experiments on rock samples. Meanwhile, the mechanical behaviour response characteristics of rock samples were discussed. Experiment results are shown as follows: (1) mechanical properties of rock samples were strengthened by closing primary pores under pre-cycling loading. The surface roughness and secondary crack number decreased gradually with the pre-cycling threshold; (2) the Kaiser effect of AE (Acoustic Emission) signals was significant in the second and third pre-cycling loading and unloading stages. The Kaiser effect disappeared in the continuous loading stage; (3) AF-RA (Average Frequency-Risetime Amplitude) signals were distributed in a dense-sparse-dense form. Low AF and high RA shear type cracks were more common. Shear failure was the dominant failure mode in rock samples.