On May 19, 2021, the world’s first super-large cross-section rectangular hard rock pipe jacking machine “Tianfei No. 1”, designed and manufactured by China Railway Engineering Equipment Group Co., Ltd. (CREG), rolled off the production line at Xiamen XGMA CREC Heavy Machinery Co., Ltd.
This pipe jacking machine will be used to excavate underground passages at Putian Railway Station, which is the first difficult project in China where multiple large cross-section rectangular pipe jacking machines pass through the railway in operation at the same time.
The project includes construction of two underground passages on the east and west sides. The eastern underground passage is 795m long and the western underground passage is 840m long. The two underground passages are both two-way, four-lane urban secondary roads. The main construction includes pipe jacking tunnels, open-cut tunnels, U-shaped grooves, open-cut entrances, etc. Once completed, the project will facilitate the travel of residents on the north and south sides of the railway station.
The excavation section of Tianfei No. 1 is 12.6 m wide and 7.65 m high. It adopts a seven-cutterhead combination arrangement with four cutterheads behind the leading three cutterheads. The cutting areas of adjacent cutterheads cross each other, and the cross-section excavation coverage rate reaches 100%. The machine has stronger rock breaking ability and tunneling efficiency that can excavate in high-strength hard rock stratum and 100MPa rock stratum. At the same time, it has very little disturbance to the ground, ensuring its safe crossing of the Hangzhou-Shenzhen railway. The rectangular pipe jacking machine will excavate a single tunnel of 260 m.
Compared with a circular tunnel, under the same cross-sectional area, the rectangular tunnel constructed by the pipe jacking machine can make the most of available space. In addition, when it used for the construction of underground passages for pedestrians, vehicles, etc., no road paving process is required, which not only saves time, but also reduces project cost. At the same time, the construction of the project using hard rock pipe jacking machine will also provide valuable experience for the construction of rectangular hard rock tunnels all around the world.