Problem
It is understood that compared with shield construction, rectangular tunnel with pipe jacking construction can make more effective use of space than circular tunnel under the same cross-sectional area; In addition, when it is used for the construction of Underpass such as pedestrian and vehicle, there is no need to carry out the ground paving process, which not only saves time, but also reduces the project cost. At the same time, the hard rock pipe jacking machine will also provide valuable experience for the construction of rectangular hard rock tunnels all over the world.
However, at the beginning of the project design, the pipe jacking machine with multi cutter head structure has the problem of milling blind area in the structural design. If the rock mass in these blind areas cannot be milled synchronously, it will not only affect the whole tunneling process of the pipe jacking machine, but also cause additional costs due to secondary milling and excavation.

We call it a shell rotary drum cutter. Its shell and the milling head are an integrated structure. It rotates at the same time when working. The spiral blade is conducive to transporting the excavated waste to the rear. They solved the milling blind area of the upper and lower edges of the "Tianfei 1" pipe jacking machine.
The other is the milling drum, which is installed on both sides of "Tianfei 1" pipe jacking machine. It is used for milling and excavating the rock mass in the blind area on both sides of the pipe jacking machine.