1. In most cases of tunnel excavation, the drum cutter is only used for excavation of contours, but in suitable formations such as medium and low hardness rock formations and frozen soil layers, the drum cutter can be directly used for tunneling. Especially when excavating broken rock layers and soft soil, the ground disturbance is low and the safety is high, and the excavation production can reach 30--60m3/h.
2. It is especially suitable for the position that is not suitable for blasting construction; the drum cutter is easy to operate, has high controllability, and the excavation contour is clear and accurate; it can easily solve the problems of undercut and trimming in the tunnel, uneven inner surface and excavation side ditch.
3. Excavation: The excavation in the field is generally carried out in two steps, namely the two-step method. Due to the need to store all the equipment on the step, the upper and lower steps are 800 - 1100 m apart. Step-by-step excavation support: After excavation, use steel mesh, steel grating + spray mixing support tunnel. When milling soft rock, the depth of each excavation depends on the condition of the face rock and the pre-design of the tunnel design unit, which is generally 50-80 cm.
4. Excavation cycle: After excavation with the drum cutter, the excavator exits the working surface and stops at the side wall of the tunnel. Then the loader starts to clean the slag, and then immediately installs the support structure, sprays work, and then repeat this cycle.
5. Problem solving: The speed of excavation of the drum cutter in clay is about 30-60 m3/h. When excavating in a clay layer, it is rare that the cutter head is wrapped in clay and cannot be used. It can be solved by rinsing the cutter head with water or by milling some dry hard surrounding rock.
