Abstract:The critical blasting vibration velocity is the key factor affecting the stability of the cemented backfill pillar. The current theoretical research is relatively weak. This paper comprehensively considers the coupling effect of overburden and self-gravity, blasting-disturbance and lateral pressure on cemented backfill pillars. And a theoretical model for the critical blasting vibration velocity of the pillar instability was constructed. Accordingly, the mathematical expression of critical velocities v_tmax, v_cmax and v_max for the tension, compression and comprehensive failure were established. Meanwhile, the relationship between the critical blasting vibration velocity of the pillar and the sand-cement ratio, height (h) and width (b) of the filling body were investigated. The results indicate that, under the external force coupling, when the pillar geometry maintains a certain value, the critical blasting vibration velocity increases with the increase of the cement sand ratio. When the width of the pillar is constant, the critical vibration velocity gradually decreases with the increase of the height, and the failure mode changes from tensile failure to compression failure. When the height of the pillar is constant, the critical blasting vibration velocity increases with the increase of the width, and the failure form of the filling body is tensile failure. The field engineering verified the rationality of the calculation results of the theoretical model. The research results provide theoretical support for mine safety production.

Key words: critical blasting vibration velocity; cemented backfill pillar; mechanical model; cement sand ratio; geometry