The Bohai Sea is the innermost gulf of the Yellow Sea and Korea Bay on the coast of North and Northeastern China. Covering approximately 78,000 km2, its proximity to Beijing, the capital of China, makes it one of the busiest seaways in the world. On the shores of the Bohai, between rows of packed buildings, a huge and eye-catching silver-white shell can now be seen glittering under the sun. It houses the biggest and deepest underground station in the world –  Yujiapu Railway Station.

 

 

Shorter Travel time

The station has been built as part of the drive to greatly shorten the travel time between Tianjin and Beijing and thus improve regional economic integration. It is the terminus of an extension to the Beijing–Tianjin rail line, China's first high-speed intercity route. Occupying 93,000m2 of land, it comprises a built area of more than 270,000m2 and provides a link to the Beijing-Tianjing-Binhai New District. The travel times from Beijing South Station to Tianjin Station, and then on to Yujiapu Station, have been shortened to 60 and 21 minutes respectively. The unique form and appearance of Yujiapu Railway Station is impressive, and  reflects the area's marine culture.

 

 

The “Shell” has half the weight of the Eiffel Tower

From the northwest, the station looks like a shell while from the southeast it  resembles a blue whale under a transparent dome. This huge “shell” is 143.9 m long from south to north and 80.9 m wide from east to west. The highest point is 25.8 m above ground. It weighs about 4,200 t, which is equal to about half the weight of the Eiffel Tower’s metallic structure. It is supported primarily by 36 direct spiral and 36 reverse spiral steel box girders that are interlaced and connected without any central support. Its weight is borne by the steel  structure and 36 foundation elements around it. Such craftsmanship is almost unprecedented in the international arena.

 

 

Unity of construction and beauty

The steel structure is covered with 700 ETFE (ethylene tetrafluoroethylene)  films of various sizes. Once inflated, each of them can support the weight of a car. Covered with transparent film, it constitutes a transparent, spacious, bright, and innovative architectural space characterized by unity of construction and beauty.

 

 

90% of the main structure is underground

 The construction and design of Yujiapu Railway Station are a departure from those employed in high-speed railway stations in the past. In addition to the exposed dome, more than 90% of the station's main structure is buried underground. Its entrance resembles the glass pyramid of the Musée du Louvre, which was designed by the renowned Chinese architect I.M. Pei. The entrance to the station is also located above ground but extends below the surface. The standards of design applied to the interior are equally high. Construction proved difficult due to the station's proximity to the sea, where saline-alkali soil had been formed by sediments accumulated over thousands of years.

 

 

A foundation pit of 130,000 m2

The permeability of the terrain also made construction work highly challenging. The foundation pit of Yujiapu Station is extremely large, with a total area of 130,000 m2, and is also very deep (31 m below the surface at the deepest point). Its irregular shape and uneven depth gave rise to extremely demanding safety requirements. The diaphragm wall is much deeper than that of regular buildings, extending as far as 65 m underground.

 

 

Demanding specification of the concrete

This is almost equal to the depth required by a building 300 m tall. The construction specifications for the concrete were also very demanding: it had to have very good workability and performance: The 2h slump loss had to be smaller than 2 cm, with the concrete strength at C30-C80.

 

 

Using PCE admixture Sika® ViscoCrete® 3301C and Sika® Retardol®

For this the high performance PCE admixture Sika® ViscoCrete® 3301C and the
retarding agent Sika® Retardol® were used. During their actual application, these products can be adjusted according to requirements and variations in materials. To ensure top quality, moreover, their formulation can be adjusted over time. The concrete produced completely satisfied the design specifications. Completion of the station has created a worthy terminus for the Beijing– Tianjin intercity rail route.

 

 

A premiere

This is the first high-speed rail project realized in China with Sika as a participant as well as a witness. Great contributions were made by both Sika products and by Sika personnel from the beginning to the end of the project – right from the construction of Beijing South Station to the construction of the Beijing– Tianjin intercity rail route and then to the building of Yujiapu station.