April 26 (Report) — The "Shendun No. 1" shield machine on the right line of the Zhangzhou project — the first domestic power project to use CT-connection-type segment lining in a shield tunnel — has recently advanced through rock and successfully passed the 100-ring milestone.

On the 26th, a representative of the project contractor, CCCC Fourth Harbor Engineering Co., Ltd., stated that the completion of this important shield construction milestone marks the mature application of key technologies for shield construction with CT-connection-type segments, accumulating rich construction experience and laying a solid foundation for the breakthrough of the Zhangzhou tunnel project.

Shi Long, project manager of the Zhangzhou shield tunnel project of CCCC Fourth Harbor Engineering, said that the drainage tunnel of the Zhangzhou shield tunnel project has a single-tube length of over 5,200 meters, making it the longest underwater drainage tunnel for coastal power generation in China at present. The shield machine has an overall length of 115 meters, an excavation diameter of 7.62 meters, and a maximum advance speed of 60 millimeters per minute.

Unlike ordinary metro shield tunnel construction, which uses bolt-type segments, the Zhangzhou tunnel project is the first domestic power project to use CT-connection-type segments in a shield tunnel. The high-precision assembly requirements of the new segments have brought enormous challenges to on-site construction.

Unlike ordinary metro shield machines, which start by breaking through the portal at the launch shaft, the shield machine at the Zhangzhou tunnel project needed to be pushed empty to the working face of the drill-and-blast tunnel for a second launch. Shi Long led the CCCC Fourth Harbor Engineering project team to ascertain the geological conditions ahead in advance, comprehensively review and check the conditions for the shield's rock-entry launch, and ensure that all tunneling parameters were normal, so that the shield machine launched smoothly.

At the beginning, the high-precision CT-connection-type assembly was unprecedented, with no experience to draw on, and segment assembly proceeded by trial and error. Each ring of segment assembly took about 90 minutes, severely constraining construction efficiency. To improve efficiency, Shi Long organized technical personnel to stay on site and carefully observe assembly details. Through repeated practice, while ensuring segment assembly quality, they continuously summarized experience and optimized the plan, successfully reducing the assembly time per ring to within 50 minutes.

Wang Guoli, the project's Party secretary, told reporters that in order to ensure the smooth tunneling of the first 100 rings, the project team strictly controlled the tunneling process and closely monitored changes in tunneling parameters. The project maintenance team was on standby 24 hours a day, ready at any time to inspect and maintain the shield machine, ensuring that it was always in optimal condition. Before shield segment assembly, all project departments jointly conducted acceptance inspections, and only after passing acceptance could the segments be put into use, ensuring tunnel formation quality to a high standard.

Shi Long stated that the techniques and procedures for the 100-ring shield tunneling have important reference value for subsequent tunnel excavation. The basic technical parameters for shield machine tunneling in different rocks, explored and summarized, have laid a solid foundation for subsequent shield tunnel construction.

"In subsequent construction, the CCCC Fourth Harbor Engineering project team will continue to firmly uphold the safety red line, vigorously improve project quality, and help the shield machine advance deeper and farther beneath the seabed," said Shi Long. After the project is completed, it will help supply clean energy and boost the high-quality economic and social development of the Zhangzhou area.