Abstract: Accroding to uniaxial rigid loading tests of sandstone, the acoustic emmission (AE) signals present sharp increase characteristics in the yield point, and the strain value corresponding to the yield point is about 74.6% of that in the peaking state. Meanwhile, the time consuming in the unsteady loading stage is relatively long, while the AE signals exit the quasi-quiet stage before the brittle failure of rock samples, and the avearege value of the duration ratio between the durations associated to quiet stage and peaking state respectively is about 8%. In addition, the damage values during the loading process are calculated based on AE information. The results show that there is a rapid growth in the yield point, and the damage value in the inflection point of stress-stain curve in the post-peak is more than 0.9. Moreover, the shape of damage-time curve before the peaking state is concave, while the curve in the post-peak shows the convex type, and the peak value locates in the inflection point of the curve.

Key words: AE, damage, rock failure test, unsteady fracture, quiet stage