边坡冲刷破坏对桥梁下部结构影响数值分析

The Numerical Analysis of the Influence of Slope Erosion Damage on the Substructure of Bridge

为了分析黄土冲沟区边坡冲刷破坏对桥梁下部结构承载性状的影响,以某桥梁下部水毁地基为依托工程,构建基于CAD地形图、ANSYS是三维地基网格的FLAC3D三维耦合数值计算模型。采用NULL单元开挖思想对边坡冲刷破坏过程进行全程数值模拟,对比分析了不同工况下桥梁下部结构承载性状的变化。计算结果表明,边坡冲刷破坏极大地改变了桥梁下部结构的边界条件和承载性状,产生附加变形和内力;由于地基卸载使下部结构回弹现象明显,墩柱侧向位移超出规范规定,长柱效应明显;上部荷载向下传递量增加,关键截面最大拉应力超出抗拉强度标准值;桩长一定深度范围内侧摩阻损失严重甚至不能提供桩侧摩阻;结论对今后黄土冲沟区桥梁下部结构的前期设计与后期加固处治具有重要意义。

To analyze the influence of slope erosion damage on the bearing capacity character of bridge substructure in loess gully, combined with a bridge substructure water damage foundation as engineering, this paper constructed the FLAC3Dthree-dimensional coupling numerical model based on CAD topographic map,ANSYS three-dimensional ground grid. Using NULL unit excavation theory, it also had the whole numerical simulation of slope erosion damage, compared and analyzed the changes of bridge substructure bearing capacity character under the different working conditions.