金塘海底隧道是甬舟铁路控制性工程，西起宁波市北仑区，东至舟山市金塘岛，全长16.18公里， 其中盾构段长11.21公里。施工采用两台盾构机从宁波侧和舟山侧同时始发，相向掘进，最终在海底实 现精准对接。隧道建成后，将结束舟山不通高铁的历史。 宁波侧盾构段要穿越高水压及多种复杂地层，经历24次频繁且差异极大的软硬地层交替变换。这种 软硬地层交替变换，对盾构机刀具、管道等磨损极大。"每掘进1米就要磕坏一颗'钢牙'，要及时对盾构 机刀盘内部的磨损刀具进行更换。"栗晨说。 人民日报记者 窦皓 临近春节，浙江宁波。风平浪静的金塘水道上方，海风吹拂，波光粼粼。乘车一路下探到地下70米 处，一条"钢铁巨龙"正在"吃进"大量岩土，延伸海底通路。 甬舟铁路金塘海底隧道宁波侧施工现场，总长135米、总重约4350吨的国产超大直径盾构机"甬舟 号"，执行的是世界最长海底高铁隧道的掘进任务。 早上7点，走进贴着火红窗花的操作室，中铁十四局甬舟铁路项目盾构机机长栗晨脱下厚重的工装 外套，坐在驾驶台前。 刀盘转速、推进速度、盾构机姿态……接下来的12个小时，栗晨要紧盯屏幕上200多组时刻刷新的 数据。每一个数据的异常波动，都可能意味着地层 ...

Core Insights - The construction of the world's longest underwater high-speed rail tunnel has achieved a significant milestone with the "Dinghai" shield machine surpassing 5,000 meters of excavation, marking approximately 80% completion of the Zhoushan side of the tunnel, which is 6,270 meters long [1][3] Group 1: Project Overview - The Jintang Underwater Tunnel is a key project of the Ningbo-Zhoushan Railway, spanning 16.18 kilometers, with the shield section measuring 11.21 kilometers [3] - Two large-diameter shield machines, "Dinghai" and "Yongzhou," are being used for excavation from both sides, facing complex geological conditions including high water pressure and various soil types [3] Group 2: Construction Challenges - The geological conditions are extremely complex, requiring the shield section to navigate through hard rock, clay, and sandy layers, presenting multiple challenges such as high intensity, high water pressure, and high precision [3] - The construction team has implemented measures such as enhanced tail seal management, optimized excavation parameters, and real-time monitoring to control ground disturbance and ensure safety [3] Group 3: Future Plans - The "Dinghai" shield machine is set to continue its progress towards the seabed connection point, with the "Yongzhou" shield machine also advancing steadily [5] - The project is expected to achieve a successful underwater connection by October 2026, with the Ningbo-Zhoushan Railway projected to be operational by 2028, integrating Zhoushan into the national railway network [5]

Core Insights - The "Yongzhou" shield machine has achieved over half of its tunneling progress for the world's longest underwater high-speed rail tunnel, marking a significant milestone in the construction of the Ningbo-Zhoushan railway [1][3]. Group 1: Project Overview - The Jintang underwater tunnel is a key project of the Yongzhou railway, stretching 16.18 kilometers, with the shield section measuring 11.21 kilometers [3]. - The tunnel employs two shield machines, "Yongzhou" and "Dinghai," which are advancing simultaneously from both Ningbo and Zhoushan sides [3]. Group 2: Technical Challenges - The geological conditions along the Jintang underwater tunnel are extremely complex, requiring the crossing of various risk sources such as sea dikes, docks, and shipping lanes [4]. - The maximum depth of the underwater section reaches 78 meters, with a maximum water pressure of 8.4 bar, equivalent to nearly 1 ton of weight on an adult's palm [4]. - The Ningbo side has experienced frequent geological changes, necessitating high-pressure tool changes, with the "Yongzhou" machine completing 12 geological transitions and changing tools over 2400 times [4]. Group 3: Strategic Importance - The Yongzhou railway is a major project in China's Medium- and Long-term Railway Network Plan (2016-2030), with a total length of 76.4 kilometers and a design speed of 250 kilometers per hour [4]. - Once operational, the project will connect Zhoushan, the only city in the Yangtze River Delta without a railway, to the national railway network, significantly enhancing regional integration and development [4].

Core Viewpoint - The approval of the feasibility study report for the Ningbo Qijia Mountain to Zhoushan Jintang section of the Ningbo-Zhoushan Expressway double line marks a significant step forward for the construction of the world's longest underwater dual-direction six-lane highway tunnel, indicating that the second channel of the Ningbo-Zhoushan Expressway will commence full construction [1][3]. Group 1: Project Overview - The total investment for the Ningbo-Zhoushan Expressway double line is approximately 31.4 billion yuan, with a total length of about 46 kilometers, designed to a dual-direction six-lane highway standard and an overall design speed of 100 km/h [3]. - The project consists of three segments, with the Jintang to Dasha segment (rail and road combined bridge) costing about 10.9 billion yuan and expected to be completed by 2028, the Ningbo Qijia Mountain to Zhoushan Jintang segment (underwater tunnel) costing about 15.7 billion yuan and expected to be completed by 2030, and the Beilun Haosifang to Qijia Mountain segment costing about 4.8 billion yuan and expected to be completed by 2029 [3]. Group 2: Technical Details - The approved section of the Ningbo-Zhoushan Expressway double line is 18.1 kilometers long, featuring the world's longest underwater dual-direction six-lane highway tunnel, the Jintang Underwater Tunnel, which is 11.6 kilometers long and utilizes 16-meter shield tunneling technology [3]. - The construction of the tunnel presents significant technical challenges, including "super large, super long, super deep" characteristics, complex geological conditions, underwater precision alignment, and underwater tunnel dismantling [3]. Group 3: Strategic Importance - The construction of this project is crucial for improving the national highway network, promoting high-quality development in Zhejiang, accelerating the construction of the Yangtze River Delta urban agglomeration, and enhancing the transportation and emergency response capabilities of the Ningbo-Zhoushan cross-sea passage [4]. - Once the double line is fully completed, the total length of the Zhoushan connected island expressway will reach 120 kilometers, further solidifying its status as China's longest connected island expressway [4].