At 11 a.m. on January 24, in the Bohai Sea area of Dajijia Town, Yantai Development Zone, Shandong Province, the receiving portal of the shield tunnel for the Yantai Port West Port Area LNG long-distance pipeline was sealed, and the shield machine host was successfully hoisted out of the shaft. This milestone marks the successful breakthrough of the key control project for the Yantai Port West Port Area LNG pipeline, signifying the smooth completion of PetroChina's first subsea shield tunnel, constructed by Pipeline Bureau Construction Company.
The Yantai Port West Port Area LNG long-distance pipeline is a critical "bottleneck project" connecting the offshore LNG receiving terminal to the onshore gas transmission network, with the offshore shield tunnel section being the key control element of this pipeline. This shield tunneling project primarily consists of a launch shaft, a receiving shaft, the shield tunnel itself, and the pipeline installation within the tunnel. The tunnel has an internal diameter of 3.08 meters and utilized a world-class slurry pressure balance shield machine for the excavation task. During construction, the project faced numerous challenges, including complex offshore geological conditions, harsh winter offshore construction environments, and the domestic pioneering effort of employing fully automated welding for pipeline installation within the confined 3.08-meter space.
To address these difficulties, the project team from Pipeline Bureau Construction Company custom-designed the shield machine equipment. It was outfitted with a special soft soil cutterhead combined with a "super-hard dragon tooth excavation matrix" of gradient-distributed alloy tools, enabling long-distance advancement through complex and unusual strata. Furthermore, the shield machine was equipped with various advanced systems and instruments, including a high-precision gas-liquid balance system, a dual-liquid grout synchronous injection system, and an intelligent segment assembly system, allowing it to better adapt to the complex and variable construction environment and meet high technical standards.
Construction on the shield launch shaft commenced on January 18, 2025, with the shield machine beginning its excavation on June 17. Throughout the construction process, the project team relied on an intelligent monitoring system to analyze geological conditions ahead in real-time, dynamically adjust excavation parameters, and conduct round-the-clock monitoring of grouting quality, sealing performance, and tool wear. The team successively overcame challenges such as sinking shafts in geology containing large boulders and tunneling along a doubly-curved tunnel axis. They successfully completed shaft construction using mechanical caisson sinking techniques and set a new record for monthly advance of 526 meters with a small cross-section slurry balance shield machine, ensuring the project progressed safely, with high quality and efficiency. On January 18, after 218 days of operation, the M1250 shield machine accurately reached the receiving shaft using an underwater breakthrough method after traversing the 1,749.15-meter-long tunnel.
Currently, Pipeline Bureau Construction Company has begun preliminary preparations for the pipeline installation inside the tunnel. Once operational, this pipeline will not only provide a continuous and stable supply of high-quality, affordable energy to Shandong, the Bohai Rim, and even North China, enhancing the region's natural gas peak-shaving, emergency storage, and winter supply security capabilities for residents, but it will also hold significant importance for adjusting the energy mix and protecting clear waters and blue skies.
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