The Świnoujście Tunnel, the longest underwater highway tunnel in Poland, recently opened to traffic. An ultra-large-diameter slurry balance shield machine, named China Railway No. 797 and developed by China Railway Hi-Tech Industry Co., Ltd. (CRHIC), a subsidiary of China Railway Group Limited (CREC), was used in the construction and excavation of the tunnel.
Thanks to the tunnel, the cross-river commuting time for residents on Uznan and Wolin Islands has been shortened from 40 minutes to just four minutes, completely transforming the centuries-old history of commuting by ferry in the local area.
China Railway No. 797 slurry balance shield machine rolls off the production line. [Photo/sasac.gov.cn]
At a length of 1,480 meters, a maximum buried depth of 26 meters, and a minimum turning radius of 300 meters, the tunnel is designed as a two-way two-lane tunnel, and the geological formation mainly consists of marine fine sand, silty clay, sandy clay with gravel, and limestone.
The tunnel presented great construction challenges due to its location beneath the Swina River, high groundwater level, and poor self-stabilization capabilities. As a result, it had high requirements for the performance and tunneling technique of the shield machine.
In view of the complex geological features and project requirements, the R&D team from China Railway Engineering Equipment Group Co., Ltd., a subsidiary of CRHIC, tailored the slurry balance shield machine, China Railway No. 797, for the tunnel's excavation. This machine boasts a cutter head diameter of 13.46 meters, a total length of about 105 meters, and a weight exceeding 2,700 tons.
The Świnoujście Tunnel, the longest underwater highway tunnel in Poland, opens to traffic. [Photo/sasac.gov.cn]
Faced with project difficulties such as shallow soil, a large diameter, and small turning radius, the team continuously optimized the targeted designs of the machine according to the customer's needs and in line with European standards. They provided the innovative design of the cutter head structure and adopted a special hinged structure on the shield system that enhanced the machine's deviation correction capabilities when turning and effectively improved its adaptability.
Since the launch of the equipment, the technical service team of CREC worked on the construction site, during which they achieved the highest daily excavation of 18 meters and 338 meters monthly.
(Executive editor: Xie Yunxiao)
