1) large-area wedge cutting
2) upper and lower wedge-shaped undercut
The large upper and lower wedge-shaped undercut holes arrangement in the centre of the heading face is recommended based on the comparison and analysis of different undercut holes arrangements in excavation of the Xiganchi water conveyance tunnel located in weak and soft surrounding rocks using smooth blasting technology.
3) wedge cut
4) vertical oblique cut
5) double wedge cut
The results of studies show that it is feasible that the development opening was excavated at the foot wall, and a well blasting effect can been achieved by using the double wedge cut.
6) vertical wedge cut