Structure Deformation Caused by Shield Tunnel Excavation Above Existing Tunnels of Shenzhen Metro
(1 School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083; 2 China Construction Communications Engrg. Group Corp. Ltd., Beijing 100161)
Abstract：
With the rapid development of subway network, it is more and more common for shield tunnels to pass through existing adjacent tunnels. The effect of adjacent shield tunnel construction on existing underlying tunnels is more complicated than ordinary metro tunnel construction. Based on the special construction condition of two-tube shield tunnel of Shenzhen metro line 9 overlapped above the existing two-tube tunnel of Shenzhen metro line 1, the laws of horizontal and vertical deformation of existing tunnel tubes induced by new shield tunneling are studied by numerical simulation and in-situ automatic monitoring, and the influence of earth pressure on the deformation of existing tunnel tubes is analyzed. The results show the in-situ automatic monitoring data basically comply with that of the numerical simulation; the effects of the excavation of the first new tunnel tube on existing tunnel tubes are larger than that of the second tube. The existing tunnel tubes generally uplift in the vertical direction, with a maximum accumulative uplift volume of 2.2 mm. The horizontal deviation of existing tunnel tubes complies with the direction of the shield driving, with the maximum horizontal deviation around 1.4 mm. The effect of the earth pressure on horizontal displacement of existing left and right tubes is roughly the same, and the horizontal displacement increases with an increase of earth pressure. Additionally, the effect of the earth pressure on the vertical displacement of the existing left and right tubes is different: the uplift volume of the left tube decreases with an increase of the earth pressure while the uplift volume of the right tube increases with an increase of the earth pressure.
2018, Vol. 55 