Numerical Investigation On Behavior Of Pile Foundation Nearby Shield Tunnelling In Shenzhen Long Gang Line

With the large scale development of urban underground space, thenumber of complicated cases of shield tunnelling which cross thestructures increases, especially in the downtown area, constructions withpile foundations like tall buildings and bridges are relatively dense,inevitably, the number of cases of shield tunnelling which cross the pilesis growing as well. The construction of shield tunnelling which crossesthe pile foundations will induce ground movement, and the movement ofsoil will induce the additional deformation and force of piles which willdo harm to the environment and outer system. This research is based onshield tunnelling construction of Shenzhen Metro Long Gang Linebetween Fuzhong Road Station and Shaoniangong Station, and usesnumerical stimulation method to analyze the impact of ground settlementand piles induced by shield tunnelling. The gist and primary new findingsof this dissertation includes:(1) Emphasis and difficulties analysis on construction. Based on theformer study on environmental effects induced by shield tunnelling, thisdissertation aims to summarize the emphasis and difficulties during theconstruction and orient the environment protection considering of thespecial strata in Shenzhen area, construction methods and groutingconditions.(2) Analysis on ground movement in field monitoring. By using thestatics method, this dissertation studied the regular pattern of ground movement while shield tunnelling crossing the pile foundations. From themonitoring results, it can be concluded that the final settlements are largerthan those when the shield machine is passing by;30days before theshield arrives at the monitoring position, the settlement starts toaccelerate; at the location of pile, the settlement is larger than that in thepile-free zone; the settlements in multi-piles zone are slightly larger thanthose in the single-pile zone; the ellipse deformation of lining matterssignificantly to the soil deformation characteristics.(3) FEM simulation of shield tunnelling crossing the pile foundation.This research utilizes FEM software ABAQUS to simulate the shieldtunnelling under different conditions of constructions. The results showthat the velocity of settlement of pile top is increasing in the5meterszone of shield’s passing-by; The settlements obtained by numericalsimulation method are smaller than monitored results; in the research ofinfluence factors of pile parameters to the simulation results, the longerthe piles are, the smaller the settlements are, while, the larger thediameters of piles are, the larger the settlements are, with the increase ofdistance between pile and axial line, the settlement of pile top increasesslow first, then decreases rapidly, finally decreases slowly. There aresudden changes in the positions of piles.