A milestone has been achieved in China National Petroleum Corporation’s first undersea shield tunneling project: the shield tunneling project for the LNG transmission pipeline in the West Port Area of Yantai Port

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On October 9, an important milestone was reached in the construction of China National Petroleum Corporation’s first undersea shield tunneling project, namely the LNG pipeline section in the western port area of Yantai Port – this project is being carried out by the Pipeline Bureau. The number of segments assembled has exceeded 1,100, and the length of tunnel drilled has surpassed 1,320 meters; these achievements represent a significant progress that lays a solid foundation for the completion of the entire tunnel. Since the excavation began in June, facing challenges such as working in confined spaces within tunnels and controlling the tunneling trajectory over long distances, the project team relied on intelligent monitoring systems to keep a 24/7 watch on the excavation parameters, as well as to monitor the quality of grouting, the sealing performance, and tool wear at all times. As the \"skeleton\" of underwater tunnels, the assembly quality of segment rings directly determines the stability and durability of the tunnel structure. The project team established a specialized technical task force to ensure the quality of assembly through three measures: first, it strictly controlled the quality of the segments used and the method of applying waterproof materials, employing a dual-layer water-stop strip design to maintain the assembly accuracy at the millimeter level ； Secondly, a pre-assembly system for segment rings and an automatic gap measurement system at the tail of the shield are employed to achieve automated segment selection and precise assembly ； Thirdly, during the segment assembly process, quality control personnel are present to monitor the entire process, ensuring that the positioning of each segment as well as the flatness of its circular surface are accurate, thereby effectively controlling misalignment and out-of-roundness. The LNG long-distance pipeline in the Xigang Area of Yantai Port is a crucial link that connects the offshore LNG receiving station to the onshore gas transmission network. Once the shield tunnel is completed, a high-pressure natural gas pipeline with a diameter of 1219 millimeters will be installed, capable of transporting 23 billion cubic meters of gas per year. Once in operation, it will significantly enhance the region’s capacity for regulating gas supply and ensuring emergency supplies in North China, thereby contributing to the achievement of the \"dual carbon\" goals.