The construction technique and the control of ground settlement of EPB shield in Shanghai

The tunnels of Shanghai Metro No.1 Line are constructed with phi 6.34m earth pressure balancing(EPB) shield. Based on a large amount of data through field measuring, the deformation and settlement of soil mass, which is caused by shield tunneling in soft clay strata, is regressively analyzed. And the regularity of the development and variation of ground surface deformation, also the range and characteristic of ground surface settlement groove, the main construction factors causing deformation are gained. It is also shown that the two kinds of construction workmanship including the earth pressure balancing of shield excavation face and field the synchronous grouting in shield tail clearance, have important effects on the controlling of the ground settlement due to shield excavation. In this paper the settlement characteristic caused by shield tunneling under structures is also analyzed, and the technical measures of controlling settlement are proposed. Finally a successful practical case of constructing under structures in subway tunnel is introduced.