盐沼泽区冻融作用下桥梁桩基腐蚀损伤模拟试验  

Simulation test on corrosion damage of bridge pile foundation in freeze⁃thaw area of salt swamp

作　　者：冯忠居[1] 郭穗柱 孟莹莹 胡海波 王富春[1] 徐占慧 姚贤华[1,3] 刘宁 FENG Zhongju;GUO Suizhu;MENG Yingying;HU Haibo;WANG Fuchun;XU Zhanhui;YAO Xianhua;LIU Ning(School of Highway,Chang′an University,Xi′an 710064,China;Qinghai Province Highway Research Survey and Design Institute,Xining 810008,China;School of Civil Engineering and Communication,North China University of Water Resources and Electric Power,Zhengzhou 450011,China)

机构地区：[1]长安大学公路学院,西安710064 [2]青海省公路科研勘测设计院,西宁810008 [3]华北水利水电大学土木与交通学院,郑州450011

出　　处：《哈尔滨工业大学学报》2021年第9期69-78,共10页Journal of Harbin Institute of Technology

基　　金：国家自然科学基金(51708040,41272285);青海省交通科技攻关项目(2014-07)。

摘　　要：为探究高寒盐沼泽区冻融循环作用下桥梁桩基的腐蚀损伤,采用室内模拟试验,模拟在养护冻融循环条件下不同桩基混凝土配合比与不同复合盐溶液体积浓度对桩基混凝土抗侵蚀性能的影响,通过对桩基混凝土外观、质量、抗压强度、动弹性模量以及微观SEM测定的方法,分析桩基础的腐蚀损伤机理。结果表明:不同桩基混凝土配合比对桩基础的抗侵蚀性能有严重影响,当在桩基混凝土中加入粉煤灰、硅灰和膨胀剂(配比Ⅲ)时,其相对动弹性模量减小不到10%,抗侵蚀系数稳定大于0.9,质量损失小于5%,桩基混凝土表面只有轻微脱落现象,能够提升桩基础抗侵蚀性能;在不同体积浓度的复合盐溶液中浸泡,桩基混凝土在冻融循环的条件下表现出不同程度的腐蚀情况,体积浓度越大,复合盐离子相互抑制作用越明显,桩基混凝土腐蚀情况减弱,当体积浓度达到15.4%时,质量损失出现负增长。由微观SEM测试结果,钙矾石、硅灰石膏、Friedel盐是导致桩基混凝土腐蚀损伤的主要产物;建议选用桩基础的设计年限折减系数为0.6,可防止冻融循环对基准体积浓度溶液腐蚀下的桩基础设计年限的不利影响。In order to investigate the corrosion damage of bridge pile foundation under the action of freeze⁃thaw cycles in alpine salt swamp areas,laboratory model test was conducted to simulate the effect of pile foundation concrete mixture ratio and compound salt solution concentration on the corrosion resistance of pile foundation concrete under the conditions of curing freeze⁃thaw cycles.The corrosion damage mechanism of pile foundation was analyzed by measuring the appearance,quality,compressive strength,dynamic elastic modulus,and SEM of the concrete.Results show that concrete mixture ratio had significant impact on the corrosion resistance of pile foundation.When fly ash,silica fume,and expansive agent(proportion III)were added to concrete,the relative dynamic elastic modulus was reduced by less than 10%.The anti⁃erosion coefficient was more than 0.9,the mass loss was less than 5%,and there was only a slight shedding on the concrete surface,which could improve the anti⁃erosion performance of the pile foundation.The compound salt solutions with different concentrations were prepared.The pile foundation concrete showed different degrees of corrosion under the conditions of freeze⁃thaw cycles,the higher the concentration was,the more obvious the mutual inhibition of compound salt ions was,and the corrosion of concrete was weakened.When the concentration reached 15.4%,the mass loss showed a negative growth.According to the SEM test results,ettringite,wollastonite gypsum,and Friedel′s salt were the main products leading to the corrosion damage of pile foundation concrete structure.It is suggested that the reduction factor of the design life of pile foundation is 0.6,which can prevent the adverse effect of freeze⁃thaw cycle on the design life of pile foundation under the corrosion of reference concentration solution.

关 键 词：桥梁桩基 高寒盐沼泽区 冻融循环 腐蚀损伤 室内模拟试验 相对动弹性模量 

分 类 号：U44[建筑科学—桥梁与隧道工程]