What are the characteristics of shaft excavation?

Rock drilling operations are generally carried out using 01-30, YT-25 or 7655 rock drills. When drilling circular sections, the blastholes are arranged concentrically. To improve the level of mechanical drilling, drilling operations can be used with the unit in the form of a ring of umbrella drilling rig.

If the water inflow from the wellbore is large, use a gel explosive or a waterproof ammonium nitrate explosive. The electric detonator detonation method is generally adopted.

Shaft ventilation is relatively easy, the general ventilation time is 15 ~ 30min, and the local fan is used for press-in ventilation. For rock loading work, the rock grabber is usually used to load the bucket, and when it is full, it is lifted to the surface by the winch. The accumulated water in the working face is discharged to the surface by using a bucket or a hanging pump.

After each blasting of the rock is completed, in order to prevent the rock in the well wall from collapsing, temporary support should be carried out in time, generally using bracket support, as shown in Figure 1.

Figure 1 Schematic diagram of shaft excavation

1-drain pipe; 2-air cylinder; 3-pressure pipe; 4- permanent bracket; 5-suspension;

6-temporary bracket; 7-rock grab; 8-bucket; 9-hang pump

When the wellbore is dug for a certain distance, a permanent bracket is built from the bottom up and the temporary bracket is gradually removed.

Permanent brackets are made of wood or concrete. There are special hanging plates when erecting permanent supports. There are various special holes on the hanging plates.