Settlement Deformation and Construction Control of Existing Tunnel Induced By Underneath Crossing of Deep Drainage Shield Tunnel.

To explore the settlement patterns of the existing tunnel structure inducted by underneath crossing of deep drainage shield tunnel and its relationship with construction control methods, a case study is conducted on the Shenzhen Qianhai- Nanshan drainage tunnel crossing underneath the existing Line 11. The essential construction factors affecting the settlement of the existing tunnel are analyzed based on field monitoring data and site conditions. The results reveal the following: (1) The settlement and deformation of the existing Line 11 tunnel is prominently correlated to construction stages and methods. (2) The unenven settlement occurs on the horizontal direction of the existing tunnel, whereas it cannot be found on roadbed. The settlement curve on the longitudinal direction presents a V shape or W shape. (3) Selecting rational soil chamber and grouting pressures and using secondary grouting and frequent supplementary grouting is conductive to settlement control of the existing structure. [ABSTRACT FROM AUTHOR]