Rapid excavation technology by drilling and blasting and it´s application in hard rock roadway

Aiming at some shortcomings of bad cutting effect, low hole utilization and small circulation footage in hard rock excavation, rapid excavation technology by drilling and blasting is proposed to improve the blasting effect for hard rock roadway from depth of blast hole, cutting form, layout of blast holes and smooth blasting. 1) Medium-deep hole is adopted to increase cycle footage; 2) Wedge-shaped cutting is benefit to overcome the rock clips and raise holes utilization in hard rock; 3) Millisecond blasting can greatly prolong action time of detonation gas and decrease maximum stress in boreholes with a rational broken particle size and even lump size; 4) Large diameter bole for the cutting hole and small diameter hole for the contour hole can save the drilling time and ensure the blasting quality. Application results show that the new rapid drilling and blasting technology can greatly increase circulation footage and hole utilization, improve formation quality of roadway and surrounding rock stability, realize average month drill footage at 120 meters and the maximum at 152 meters.