流速对深水锁扣钢管桩围堰侧向变形影响研究

以某城市快速路跨河大桥桥墩锁扣式钢管桩围堰施工为背景,利用Plaxis 3D三维建模,模拟了围堰分步施工过程,研究了仅静水压力及考虑静水、流水压力共同作用下围堰侧向变形空间效应。基于此,分析了不同流速、钢桩直径、嵌入深度及围护结构形式对侧向变形的影响。结果表明：静水与流水压力共同作用下围护结构迎水面侧向变形远大于仅考虑静水压力,最大变形出现在中心线处；迎水面侧向变形分布与明渠流垂向流速分布规律一致,最大变形点位于流速最大对应深度处；增大钢桩直径可有效减弱围堰侧向变形程度,当钢桩嵌入中风化砂岩后,嵌入深度对侧向变形影响不大；采用圆形围护结构形式可极大地降低水流力对围堰侧向变形的影响,且整体受荷情况与变形分布较矩形更为均匀。

Influence of Uniform Flow in Open Channel on Horizontal Deformation of Steel Pipe Pile Cofferdam

Based on the construction of lock type steel pipe pile cofferdam of bridge pier of a city expressway bridge, the modeling of PLAXIS 3D is used to simulate the construction process of cofferdam step by step, the spatial effect of lateral deformation of cofferdams under hydrostatic pressure alone and considering the combined action of hydrostatic pressure and flowing water pressure is studied. Based on this, the influence of different velocity, diameter of steel pile, embedded depth and retaining structure form on lateral deformation is analyzed. The results show that: Under the combined action of hydrostatic pressure and flowing water pressure, the lateral deformation of the upstream surface of the retaining structure is much larger than that under the consideration of hydrostatic pressure only, and the maximum deformation occurs at the center line; The lateral deformation distribution of the upstream water is consistent with the vertical velocity distribution of the open channel flow, and the maximum deformation point is located at the maximum corresponding depth of the velocity; The lateral deformation of cofferdam can be reduced by increasing the diameter of steel pile. When the steel pile is embedded in moderately weathered sandstone, the depth of embedded steel pile has little influence on the lateral deformation; The circular enclosure can greatly reduce the influence of flow force on the lateral deformation of cofferdam, and the overall load and deformation distribution are more uniform than rectangular.