Abstract:Based on the previous research on structural and flow characteristics of swirling jet,the testing study is made to analyse the factors affecting rock breaking efficiency of swirling jet,such as pump pressure,jet distance,rock permeability and intensity,consistency of additive,etc. Meanwhile the distinction of the effects of rock permeability on swirling jet and straight jet is studied. The results show that rock breaking efficiency by swirling jet apparently increases with the decrease of rock strength and the increase of rock permeability at the same standoff distance and pump pressure. The rock permeability plays important role in the rock breaking effect of jet. The effect of rock permeability on the swirling jet is greater than that on the straight jet. Meanwhile the results show that the depth,diameter and volume of the hole drilled by swirling jet apparently increase at the beginning and decrease afterwards with the increase of consistency of additive. The most excellent consistency of additive is 200~300 mmp in this experiment.