基于FLAC 3D的盾构施工穿越高架桥梁桩基稳定性影响数值试验研究

Numerical Experimental Study on Influence of Shield Construction on the Stability of Viaduct Pile Foundation Based on FLAC 3D

针对盾构施工对桥梁桩基影响特性,利用FLAC 3D有限元数值软件建立网格模型,分析了简支梁与连续梁桥两种结构形式下,不同穿越形式工况下桥桩位移变化特征。研究了盾构不同穿越简支梁桥桩时,桩身X、Y、Z向位移分布变化以及各穿越形式工况下的差异性特征,其中前排桥桩Z向沉降变形高于后排桥桩,下穿越形势下左侧桥桩沉降高于右侧,6#桥桩沉降稳定在0.26mm。获得了盾构穿越连续梁桥时X向位移具有递增态势,远近测桥桩Y向位移变化斜率为一致,侧穿越桩基上部时每米桩长增长位移值约0.15mm,4#桥桩为最大沉降变形,其中下穿越形式下最大,达8.1mm。对比了两种梁桥结构下穿越形式时,简支梁桥位移值水平向位移或沉降变形均是最大,受盾构施工扰动影响较敏感。研究结论为研究盾构施工对桥梁桩基影响分析提供一定参考。

Aiming at the influence characteristics of shield construction on the bridge pile foundation,the grid model is established by utilizing FLAC 3D finite element numerical software,and the displacement change characteristics of bridge pile under different crossing conditions are analyzed under two kinds of structural forms like simply supported beam bridge and continuous beam bridge.The displacement distribution change of X,Y and Z directions of the pile body and the difference characteristics under different crossing conditions are studied.In which,the Z-direction settlement deformation of the front row pile is higher than that of the back row pile,the settlement of the left bridge pile is higher than that of the right side under the lower crossing situation,and the settlement of 6#bridge pile is stable at 0.26mm.The displacement in X direction increases with the shield passing through the continuous beam bridge.The change slope of the Y-direction displacement of the bridge pile is the same in the far and near measurement.The increment displacement value of the pile length per meter is about 0.15mm when the shield passes through the upper part of the pile foundation,and the maximum settlement deformation of 4#bridge pile is 8.1mm under the lower crossing mode.The horizontal displacement or settlement deformation of the simply supported beam bridge is the largest when the two types of bridge crossing are compared,which is more sensitive to the disturbance influence of shield construction.The research conclusion can provide a certain reference for the analysis of the influence of shield construction on bridge pile foundation.