Research on Shaft No.1 of the Yan’an Donglu Tunnel

The 2261m long Yanan Donglu tunnel is the second one that crosses the Huang Pu River, Shanghai with the shield 11.26m in diameter. Shaft No.1 with 28m in diameter and 30m in depth located in the centre area of Shanghai, and was built on soft clay foundation using diaphragming method with excavation depth of 18.7m. Since problems remained both in design and construction for this kind of large shafts, some research works have been done, including the instrumentation for monitoring in the field, tests of the centrifuge model and special geotechnical tests for analyses and calculation.