After tunneling through sandy gravel for nine and a half months, on Tuesday, October 9, 2018 the slurry pressure balance shield machine (SPB) from CRCHI "Yuan An" achieved a breakthrough at the reception shaft and completed its drive for the east line of Yuan River Tunnel Project. The tunnel project, constructed in the city of Changde, China, starts from Yangming Road to Zaoguo North Road and is city's landmark project. The tunnel connects two sides of the river and will promote harmonious development of regions along the river.
Since launched, "Yuan An" has achieved excellent performances under the Yuan River of 11 rings (22 meters) per day and 181 rings (362 meters) per month. The machine was specially designed with the technology of cutter replacement under normal pressure which has proved very successful and got much public attention. In the cross-river project, a total of 280 cutting tools were changed in a smooth, safe, reliable and high-efficient way, indicating that CRCHI has grown mature in developing and applying the technology of replacing cutters at ordinary pressure.
Technical Records of "Yuan An"
The SPB “Yuan An” was usable in high water pressure and for the long-distance tunneling with high requirement on ground settlement.
Thanks to the the self-developed technology of cutter replacement under normal pressure, the SPB drove in a high-efficiency and safe way as it took only 40 minutes for workers to replace a cutting tool and it was safer for the people under normal environment than under pressure. Application of a high precision gas-liquid pressure balance control system guaranteed the pressure was always kept balanced between the tunnel face and the excavation chamber. A big-power slurry circulation flushing system ensured high-efficiency excavation and delivery. An alloy-toothed crusher was hydraulic-driven and had high crushing efficiency. Besides, application of box culvert synchronous installation technology allowed for the assembly of precast box culverts parallel to tunneling, effectively shortening the construction period.
Service for the whole life cycle of the equipment
The SPB wouldn't have achieved breakthrough without efforts of CRCC 14th (construction unit) and service supports from CRCHI. CRCHI offered whole-life-cycle service to the customer.
During trial boring, CRCHI service team stayed at the jobsite the whole day long to ensure primary tunneling. After that time, mechanical, electrical and hydraulic engineers didn't leave the site until the task was finished, ensuring stable operation of equipment. Their skills and dedication laid the solid foundation for breakthrough of the east line.
Ready for the construction of west line
We have got some technical and construction experience from east line, which paves the way for the future construction of west line. As planned, “Yuan An” will be delivered to the job site at the west line for recombination after dissembled. It will be launched by the end of 2018 or in January of 2019 for driving west line tunnel. We are expecting the mission to be completed successfully.