Research On Supporting Of Deep Foundation Trench Under Complex Environmental Conditions

In this paper, the deep foundation trench of Cheng Fu Road tunnel which is belong to the Olympic Park municipality engineering is used as the background of research. The depth of the foundation trench excavation is about 19 meters. Directly digging foundation method is designed for the engineering. As the tunnel is in the Olympic Park, the main Olympic venue-Bird'Nest is in its south, the underground garage of Bird'Nest is in its north, and the tunnel is connected to the underground circular tunnel of Olympic Park, so the construction site is very narrow, the surface and underground environment along the tunnel is extremely complex.Due to the complex environmental conditions, the scheme of deep foundation trench supporting has been optimized. By comparing several supporting schemes by the technical and economic factors, finally a best supporting scheme is chosen with supporting theory of foundation pit and the conditions of this construction. Anchor-retaining pile structure and soil nailing wall structure are all used.Use PLAXIS to compare different programs of anchor-retaining pile structure, after the analysis, three rows anchor-retaining pile structure is chosen. After calculating, it is found that, the security of piles is good, the horizontal displacement and the vertical displacement are small. The acceptance of pre-stressed anchor is done in the construction site, and the results meet the requirement of specifications.Use FLAC^3D to do the numerical simulation of the soil nailing wall structure, analysis of the horizontal displacement, vertical displacement and the distribution of plastic zone. Simulation results show that the horizontal displacement and the vertical displacement can be well controlled by soil nailing retaining structure, and the plastic deformation of soil is delayed.The displacement monitoring of the foundation trench is done over the slope of foundation trench supporting, and the displacements meet the requiement. Choose some monitoring points of the soil nailing wall, the measured data are close to the numerical simulation results. Numerical simulation is proved to be an effective analysis method.