| Located in areas with intensive buildings, roads and underground pipelines, it is a common practice that the deep foundation pit engineering in urban, due to the straitness of the construction yard, be situated neighboring closely to the viaduct of the city, which would pose stricter demands to the safeness and deformation limit of the bracing of the foundation pit. The viaduct in operation on the one hand should bear the loads of the vehicles, which means it will be sensitive to the settlement and the difference in settlement, on the other hand, it will not be exempted from the influence of the neighboring foundation pit and becomes more complicated in stress. The excavation of the foundation pit would cause a displacement of the soil nearby, and this displacement would trigger a differential settlement, which would induce a deformation of the upper structure. With the increase of the horizontal displacement of the soil, an additional deflection and bending moment would occur on the piles nearby, and when the bending moment and the deformation become too large, the piles would break down.The deep foundation pit of the metro station of Fengyang Road, which belongs to the first stage construction of the rail transit line 1 of Hefei city, is situated under the intersection of Shengli Road and Fengyang Road, and it is positioned along the Shengli Road, north to south. The station is under the viaduct of Fengyang Road, and the minimum distant to the piles of the viaduct is 14 m. On cace that the bracing of the fondation has an over limited deformation, it will cause a large displacement of the outward soil, and that will produce an additional stress and settlement of the piles of the viaduct, whose bearing capacity would be reduced, which would threaten the safeness of the viaduct in operation. Thereby, a scheme that should ensure a fast construction and the safeness of the in operation viaduct near the fondaton pit becomes an issue of top priority.Affected by the geological conditions, the fondation engineering has a regional characteristic. Thereby, this thesis is associated with the engineering practice of the deep foundation pit of the metro station of Fengyang Road, a station of the rail transit line 1 of Hefei city. Based on the prior knowledge as references and combining with the in situ monitoring data and engineering experiences, the numerical simulation method is adopted to analys the mutual influence of the excavation of the fondation pit and the piles of the viaduct. A fast construction scheme is proposed, which would undoubtly has great significance to the designing and construction of the deep foundation engineering in Hefei. |
