Study On The Subway Tunnel Structure Influenced By The Construction Of The Deep Foundation Pit Under The Complex Geological Conditions

In recent years, the position of the subway is more and more imperative now. But the space under the ground becomes much complex because the subway tunnels through the space under the city, it makes the structure of the underground space is particularly complex. It would be a big problem for the excavation, if the worker was careless slightly; the serious engineering accident would be happen. In order to avoid such things happen, It is necessary to know the influence-mechanism for subway of the deep foundation pit which above the subway structure in complex geological conditions of the soil.This paper is based on the real engineering of Dong Huan square between the east of Chan He station and Chang Le Po station, both the two station belong to the line 1 subway. This paper mainly study the change rule of the displacement and mechanical properties of tunnel structure under the deep foundation pit excavation and loading at the top of the pile which under the foundation. This paper summary the following conclusions through the geotechnical centrifuge test and the numerical simulation.1. In the process of excavation, the stress and the displacement as well as the pressure of the tunnel structure is affected obviously. The stress and pressure are showing a decreasing trend around the tunnel, and the most significant change at the top of tunnel. The tunnel displacement quantity of the Y direction is greater than the X direction displacement changes, that is to say the whole tunnel shows the trend to be ?elongated‘.2. As the pile foundation load is increasing under the foundation pit bottom, the stress and pressure as well as the displacement of the tunnel structure is not very change hugely. The pressure and stress variation at the bottom of the tunnel is greater than the top of the tunnel, and the stress and pressure variation on both sides of the tunnel roughly the same. The maximize vertical displacement change of the tunnel is the top of the tunnel, and the maximize horizontal displacement change of the tunnel is in the lateral tunnel.3. In the process of pile foundation loading, the pressure, stress and horizontal displacement of the inside of the double-line tunnel cross-section which is close to the pile changes in values relative to the other cross-section tunnel. And the stress of the end of the tunnel is far away from the stress of the central tunnel which in the scale of the pile foundation.4. In the process of deep foundation pit construction, the excavation is more serious than pile foundation loading effects on degree of various factors of the tunnel.