The holes in the tunnel section are generally divided into several types such as cut holes, auxiliary holes, peripheral holes, and bottom holes.
Cutting eye: The function is to increase the free surface. Slant eye cutting is commonly used in tunnels. Occasionally use a straight eye to dig.
Auxiliary eye: expand around the grooved eye layer by layer. In the blast control network, with the cutout eye as the center, the differential layout is layer by layer, which plays the role of transmitting and amplifying the blasting effect.
Peripheral eye: Its main function is to control the blasting excavation contour.
Bottom hole: The last link of section blasting is not only for blasting, but also for loosening and turning up the blasted rock ballast in the section. It is also called bottom hole turning.
If you adopt the method of squinting the eye, you need to gradually reduce the inclination angle in the first circle of auxiliary eyes. Rather than straightening it all at once.