Solution for Blind Area of Pipe Jacking Machine
On May 19, 2021, the world's first largest cross-section rectangular hard rock pipe jacking machine "Tianfei 1" was delivered offline. This pipe jacking machine will be applied to the railway related embedded project of Putian railway station. It is also the first difficult project in China where multiple large cross-section rectangular pipe jacking pass through the operating railway at the same time.
The excavation section of "Tianfei 1" is 12.6m wide and 7.65m high. It adopts the combined layout of two layers, three front, four rear and seven Cutterheads. The cutting areas of adjacent Cutterheads cross each other, the section excavation coverage rate is 95%, and it has stronger rock breaking capacity and tunneling efficiency. It can dig in high-strength hard rock strata and rock strata meeting 100MPa, with little disturbance to the stratum, To ensure that the safety risk of Undercrossing the existing Hangzhou Shenzhen railway is controllable.
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.
Therefore, the leaders of China Railway contacted Yichen company in the hope that Yichen could provide a solution to the problem of milling blind area of pipe jacking machine. In this case, Yichen designed and manufactured two milling modules for customers by using its R & D strength and many years of practical experience, which effectively solved the problem of milling blind area.
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.
"Tianfei 1" pipe jacking machine can complete the milling and excavation of the whole square surface at the same time after it is equipped with a shell rotary drum cutter and a milling drum designed and customized by Yichen. It has completely solved the problem of construction blind area, greatly reduced the construction cost, and laid a solid foundation for the completion of Putian railway station project on schedule.