The Yangtze River Delta is one of the most vibrant regions in China. The fastgrowing area on the east coast represents more than a tenth of China’s population and contributes about a quarter of China’s economic output. The national strategy of regional integration and high-quality growth is adding further momentum to the region with 27 urban cities.
This has resulted in emphasis being placed on accommodating the needs for both population and business activities to cope with the high density. Among others, efficient traffic infrastructures, for example, extra-large highway networks with higher capacities become indispensable. Under the strategic vision, over the years around two dozen gigantic Herrenknecht TBMs with a diameter exceeding the 14-meter mark have played a significant role in realizing highly efficient road tunnels. They have been deployed both in Wuhu’s quartz sandstone with a strength of up to 113.4 MPa and in the sedimentary soils of Shanghai, for instance.
Extra-large diameter tunnelling poses great challenges on its own as the diameter grows larger. Together with three of Herrenknecht’s most loyal customers, attention was first focused onto dealing with exponential increases of the installed cutting wheel torque and power, required thrust and capacity of removing excavated materials in the phase of devising the TBMs. Complex project-specific conditions, such as long distance tunnelling up to 7.47 kilometers in Shanghai, a complex tunnel alignment mixed with high or shallow overburdens in Jiangyin, high face pressure of up to 10 bars under the Yangtze river, or facing mixed ground with abrasive soils or fault zones as in Nanjing and Wuhu, compound the tunnelling complexity.
24 of these behemoths weighing thousands of tonnes are Mixshields, which are definitively in their element when overcoming river-crossing tunnel alignments. Due to the tunnel face support automatically controlled by air cushioning, sudden pressure and volume fluctuations as in Nanjing can be balanced precisely, essential for operations with high water pressures and very large diameters.
Herrenknecht already amazed the global tunnelling world with its two recordbreaking TBMs (15.43 meters) for the Shanghai Yangtze River Crossing project in 2006. Since then, meticulous and detailed analysis and engineering have been conducted step by step. The Herrenknecht supersized TBM and its features have therefore never ceased being developed, aiming to realize the ultimate in safer operations within such dimensions. In particular, the accessible cutting wheel, sealing or real-time monitoring systems have been improved based on the project expertise accumulated over the 15 years.
The Yangtze River Delta (YRD) in East China developed rapidly to become one of the largest urban areas in the world. Centered around Shanghai, the YRD region extends across three neighboring provinces of Zhejiang, Jiangsu and Anhui, with an area of 358,000 square kilometers in total. The YRD contributes about a quarter of China’s economic output despite its covering only 3.7 % of the country’s total land mass. The expansion of the infrastructure is progressing quickly too. In this connection numerous lakes and rivers need to be crossed under. Since 2005, Herrenknecht has been delivering supersized tunnelling technologies and services to the YRD.
|Client||Numerous Chinese local authorities for infrastructure|
|Contractor||China Railway 14 Bureau Group Corporation|
Shanghai Tunnel Engineering Co., Ltd. (STEC)
Shanghai Foundation Engineering Group Co., Ltd.
|Geology||Alluvial deposit soils in the main stratums, bedding rocks partially encountered in individual projects.|
|Tunnelling length||95,723 m (in total)|
|Machine data||2 × EPB Shield|
Diameter: 14,410 mm
Cutterhead drive power: 3,250 kW, 7,000 kW
24 × Mixshield
Diameter: 14,900 – 16,060 mm
3,750 – 5,600 kW