Key techniques and important issues for slurry shield under-passing embankments: A case study of Hangzhou Qiantang River Tunnel

• We compare settlements of the embankments and the greenfield to find out the influences of structure types.
• We compare the shield excavation parameters above the twin tunnels to assess the influences of shield excavation parameters.
• We compare the embankment movements of in-construction and post-construction.
• We give the key techniques and important issues for settlement control during slurry shield traversing the embankments.

Hangzhou Qiantang River Tunnel is the first cross-river tunnel under Qiantang River, and it is also the first practice of slurry shield tunnelling in the soft ground in Hangzhou. For lack of experience in slurry shield under-passing embankments in Hangzhou, ground surface movement monitoring and intensive analysis and comparisons of the measured results were executed to explore the key techniques to minimize the embankment settlements arising from tunnelling. This case study summarizes the primary factors influencing the embankment settlements and puts forward the key techniques and important issues for settlement control during slurry shield under-passing.