CREG developed and manufactured the equipment – a combination of a pipe jacking machine and a shield machine – to overcome the difficulties in constructing the 900m cable tunnel. The length of the tunnel, its large diameter, deep depth and drift sand stratum meant it could not be built using traditional methods.
The pipe jacking shield machine includes a pipe jacking machine and an expansion module of a shield machine. The main machine consists of a cutterhead, drive unit, shield structure and muck-discharging system while the expansion module comprises shield, thrust cylinder and segment erector.
In operation, once the jacking limit has been reached for pipe jacking machine mode, the machine converts to shield machine mode and continues until the tunnel is broken through.
In the project in Henan province, a distance of 750m was excavated by pipe jacking machine mode and the remaining 150m by shield machine mode. The machine was launched in December 2021 and its highest daily advance speed was 42.5m.
CREG says that compared with the traditional pipe jacking method, the pipe jacking shield machine not only adapts to construction in narrow urban spaces, but also meets the demands of long distance and small turns. At the same time, it can reduce the use of intermediate shafts or stations in long-distance tunnelling, and meet the laying of various complex pipelines in urban areas.
“Compared to a regular shield machine, the pipe jacking shield machine is more convenient and efficient and can save almost two-thirds of construction costs so it has huge economic and societal benefits,” CREG says.
