In order to overcome the defects such as short single cycle footage

low utilization of blast-hole

too many blasting fragment pieces assembled near the roadway heading face

insufficient excavation of dip roadway floor and so on

that often occur in dip roadway excavation

the new cut formation of wedge cut with assisted holes that used to enhance the thrown effect of fragment pieces is designed. The designing of the new cut formation bases on the new idea that using the middle empty holes to assist the broken cut holes in throwing the fragment pieces out of the cut cavity during the blasting. For the sake of proving the advantage of the new cut formation

many in-situ experiments are conducted in the Huaheng coal mine. By means of changing the layout of the cut holes

changing detonating sequences

setting special auxiliary holes to increase the throw distance of the blasting fragment pieces

and using mixed arrangement type of auxiliary holes

three kinds of design schemes of dip roadway blasting excavation are formulated. Through the analysis of single cycle footage

depth of the blast-hole left after blasting

outline of the laneway after blasting

thrown distance of the fragment pieces

lumpiness of the fragment pieces

and height of the fragment pieces in front of the roadway heading face

the perfect blasting design is put forward

of which the overall indicator is the best. Thanks to the technique

the single cycle footage of the coal mine increases by 40% everymonth. The success of the test proves the validity of the technique to overcome the defects in coal mine dip roadway excavation.