The Study Of The Impact On The Existing Bridge Pile By Subway Shallow Excavation

In recent years, with China’s rapid urban development, the traffic congestion on the ground is being serious, which causes people more and more put their eyes on the use of underground space resources. To ease the traffic pressure on the ground, major cities have been constructing the underground rail transit. Subway tunnel construction under more restriction by ground and underground environmental, at the time of crossing near building foundations will lead to the displacement of the soil around the foundation, thus making the pile to generate additional internal forces and deformation, resulting in the overall appearance or uneven settlement of the upper structure, thereby endangering the safety of using bridges and buildings. Therefore, there is a important reference significance for construction.to study the impact of exit pile foundation duing to Shallow Mining Method construction.In this paper, based on Summarizing of previous research results, the relationship between tunnel excavation and pile displacement,axial force and friction being analysised,the main work is carried out in the following areas:(1) Analysising the soil displacement and main factors induced by tunneling, Loganathan analytical solution formula is used to calculate the displacement of soil caused by tunneling. The influence of existing bridge piles caused by soil vertical displacement is anysisied, then a single pile and pile group displacement equations by shear displacement method is established, solving equations and gaining the pile displacement and axial force function. A single pile and pile group displacement equations by shear displacement method is also established before the tunnel excavating, solving equations and gaining the pile displacement and axial force function.(2) Based on derivation formula of pile displacement and axial foce, which is applied to compute the pile displacement and axial force before tunnel excavating.The soil vertical displacement caused by the excavated is used to fit polynomial,which is applied to calculate the tunneling-induced deformation and stress changes of pile and group piles in specific examples of engineering. At last, the pile parameters are analyzed.(3) Through the construction site monitoring, data acquisition and analysis,we gain the settlement rule of surface and draw bridge pile. Using of the finite difference software FLAC3 D to establish numerical model, we caculats the settlement of soil and bridge pile for the actual construction method,and obtained the distribution pattern. Comparing the results we gained, the calculations accuracy is verificated through the simulation results and practical monitoring data.(4) The control standards for existing norms of bridge pile are summarized The consolidation range is determined based on the result of calculation.Propose measures to control the deformation of the bridge piles, which could provide guidance and reference to the project construction.