透水牺牲桩减少上下游桥墩局部冲刷深度及机理  

Mechanism of permeable sacrificial pile to reduce local scour depth of longitudinal double piers

作　　者：齐洪亮[1] 罗文俊 王杰[1] 田伟平[1] 李家春[1] QI Hong-liang;LUO Wen-jun;WANG Jie;TIAN Wei-ping;LI Jia-chun(Key Laboratory for Special Area Highway Engineering of Ministry of Education,Chang'an University,Xi'an 710064,Shaanxi,China)

机构地区：[1]长安大学特殊地区公路工程教育部重点实验室,陕西西安710064

出　　处：《长安大学学报（自然科学版）》2024年第2期68-79,共12页Journal of Chang’an University(Natural Science Edition)

基　　金：中央高校基本科研业务费专项资金项目(300102213208);交通运输部在役干线公路基础设施与安全应急数字化试点项目(303);国家重点研发计划项目(2022YFC3002600);国家自然科学基金项目(51708043);陕西省自然科学基础研究计划项目(2019JQ-680)。

摘　　要：针对工程实际中常见的上下游桥墩局部冲刷的防护问题,通过室内模型试验和数值模拟相结合的方法,研究清水条件下采用透水牺牲桩进行前墩局部冲刷防护时,透水牺牲桩填充碎石粒径和淹没率2个因素对透水牺牲桩自身和上下游桥墩局部冲刷特征的影响规律。研究结果表明:无牺牲桩防护时,上下游墩的局部冲刷深度都随墩心距的增大呈先减小后增大的规律;当墩心距为4D(D为桥墩直径)时,前墩对后墩局部冲刷的防护效果最好;相同条件下(最佳墩心距)分别采用实体牺牲桩和透水牺牲桩对上下游桥墩进行防护时,二者均能有效减小上游桥墩的局部冲刷,透水牺牲桩防护时效果更好,且自身局部冲刷深度较实体牺牲桩可减小约30%;采用透水牺牲桩防护时,当其填石粒径为0.2D~0.25D、淹没率为1时,减冲效果最好;透水牺牲桩的透水性允许部分水流从桩身内部流过,有效减小了桩前下潜水流的强度,减轻了其掏底作用,从而有效减小了局部冲刷深度;与采用实体牺牲桩防护相比,透水牺牲桩及上游桥墩两侧的最大剪切应力分别约为前者的1/2和1/4;透水牺牲桩桩后低剪切应力区的范围更大。In view of the common problem that local scour protection of longitudinal double bridge piers in engineering practice,the influence of two factors,namely the particle size of gravel filled with permeable sacrificial piles and submergence rate,on the local scour characteristics of permeable sacrificial piles and longitudinal double bridge piers were studied,under the condition of clear water using the combination of indoor model test and numerical simulation.The results show that the local scour depth of longitudinal double piers decreases first and then increases with the increase of pier center distance without sacrificial pile protection.When the pier center distance is 4D(D is the pier diameter),the front pier's protection effect against the rear pier's local scour is the best.Under the same conditions(the best pier center distance),when the solid sacrificial piles and permeable sacrificial piles are used to protect the longitudinal double piers respectively,both the local scour of the upstream piers can be reduced effectively,and the permeable sacrificial piles are better for protection,and the local scour depth of the self can be reduced by about 30%compared with the solid sacrificial piles.When permeable sacrificial piles are used for protection,the best effect is achieved,when the particle size of the rock fill is O.2D to 0.25D and the submergence rate is 1.0.The permeability of the permeable sacrificial pile allows part of the water to flow through the pile body,the strength of the submerged flow is reduced effectively in front of the pile,its bottom digging effect is reduced,and the local scour depth is reduced effectively.Compared with solid sacrificial pile protection,the maximum shear stress on both sides of the permeable sacrificial pile and upstream pier is about 1/2 and 1/4 of the former respectively.The range of low shear stress zone behind permeable sacrificial pile is larger.

关 键 词：桥梁工程 上下游桥墩 模型试验 数值模拟 透水牺牲桩 清水冲刷 

分 类 号：U447[建筑科学—桥梁与隧道工程]