山区公路桥梁双桩基础磨蚀数值模拟研究

Numerical simulation study on erosion of dual pile foundation of mountainous road bridge

摘要

为研究山区公路桥梁双桩基础在携砂水流作用下的磨蚀分布规律，基于Fluent软件建立双桩基础的三维磨蚀数值模型，采用DPM模型模拟泥沙颗粒，并结合Finnie磨蚀预测公式，开展不同水流流速、泥沙颗粒粒径、含砂率、桩基壁面粗糙度及双桩的排列型式条件下双桩基础磨蚀分布特征研究。结果表明：桩周的流速分布对桩基的磨蚀分布影响较大，前桩的磨蚀相对稀疏，主要分布在迎水面两侧，而后桩受前桩尾流区的影响，磨蚀分布较为密集；随着水流流速的增大，桩基最大磨蚀率的整体变化趋势为增大，但达到一定的速度后，增幅下降；随着泥沙颗粒粒径、含砂率及桩基壁面粗糙度的增大，桩基最大磨蚀率亦增大。其中，对于泥沙颗粒粒径和桩基粗糙度，当增大至一定数值，桩基最大磨蚀率增大的速度下降，而含砂率增大至一定数值时，桩基最大磨蚀率增大的速度增加。随着桩中心距增大，串联双桩的前后桩最大磨蚀率均增大，且增幅逐渐减小，而并联双桩的左右桩最大磨蚀率先增大后减小。

Abstract

Aimed to investigate the erosion distribution characteristics of dual pile foundations of mountainous road bridges under sand laden flow, a three-dimensional erosion numerical model of the dual pile foundation was established using Fluent. The DPM model was employed to simulate sediment particles, and the Finnie erosion prediction formula was combined to explore the erosion distribution characteristics of the dual pile foundation under different water flow velocities, sediment particle sizes, sediment concentration, pile wall roughness and arrangement type of double piles. The result show that the velocity distribution around the piles has a significant influence on the erosion distribution of the pile foundation. The erosion of the front pile is relatively sparse, mainly distributed on both sides of the water-facing surface, while the erosion distribution of the rear pile is more concentrated due to the influence of the wake zone of the front pile. With increasing water flow velocity, the overall trend of the maximum erosion rate of the pile foundation increases, but the rate of increase decreases after reaching a certain velocity. Moreover, as the sediment particle size, sediment concentration, and pile wall roughness increase, the maximum erosion rate of the pile foundation also increases. Specifically, for sediment particle size and pile wall roughness, when increased to a certain value, the rate of increase in the maximum erosion rate of the pile foundation decreases, while for sediment concentration, when increased to a certain value, the rate of increase in the maximum erosion rate of the pile foundation accelerates. With the increase of pile center distance, the maximum erosion rate of the front and rear piles of the tandem double pile increase, and the increase decreases gradually, while the maximum erosion rate of the left and right piles of the parallel double pile increase first and then decreases.

关键词

双桩基础 / 磨蚀分布 / 数值模拟 / 最大磨蚀率 / 变化趋势

Key words

dual pile foundation / erosion distribution / numerical model / maximum erosion rate / overall trend

Author summay

白晓宇(1991—), 男, 工程师, 博士, 主要从事桥梁防灾减灾方面的研究。E-mail: [e-mail]

基金资助

国家自然科学基金项目(52378135)

国家自然科学基金项目(52022021)

国家自然科学基金项目(51978160)