PHC管桩三种常用金属端头在土壤模拟液中的电化学腐蚀行为

金属端头的耐蚀性取决于其各部件(包括端板、裙板和主筋)的材质，进而影响预应力高强混凝土管桩(PHC管桩)的耐久性。通过自然浸泡和电化学测量技术研究了实际工程中PHC管桩三种常用金属端头(其中端板分别用铸钢、冷弯钢和Q235A钢)在四种典型土壤(氯盐土、盐碱土、中性草甸土和酸性红土)模拟液中的腐蚀行为。结果表明，实际工程所用端板的腐蚀速率均小于主筋和裙板，铸钢端板加速裙板和主筋腐蚀的程度不如冷弯钢或Q235A钢端板，但铸钢端板本身耐蚀性极差；端板与裙板、端板与主筋在土壤中存在接触电偶腐蚀，端板/裙板电偶对中裙板均为阳极，铸钢端板/主筋电偶对在盐渍土中铸钢为阳极，冷弯钢或Q235A钢端板与主筋电偶对中主筋也均为阳极；接触腐蚀加速了薄壁裙板和小面积主筋的破坏，将导致预应力的过早失效；现有金属端头需进行防腐蚀控制。

Electrochemical Corrosion Behaviors of Three Commonly Used Metal Ends of PHC Pipe Pile in Simulated Soil Solutions

The durability of Prestressed High-strength Concrete (PHC) pipe pile is affected by the corrosion resistance of their metal ends, which depends on the material of end plate (EP), apron (AP) and pretensioned PC steel bar (PC). There are three kinds of EPs: cast steel, cold-bended steel and Q235A steel, which are widely used in pratical engineering. Their electrochemical corrosion behaviors in four typical simulated soil solutions including chloride salt soil, salina soil, neutral meadow soil and acid soil were investigated by natural immersion tests and electrochemical measurement techniqus. The results show that the corrosion rate of three kinds of EPs is smaller than that of PC and AP. The corrosion of PC and AP accelerated by cast steel EP is smaller than that by cold-bended steel and Q235A steel; but the corrosion resistance of cast steel EP is poor. There is contact galvanic corrosion between EP and AP, EP and PC in simulated soil solutions. In couple of EP/AP, AP is anode. Cast steel EP is anode when the galvanic couple of cast steel EP/ PC was in saline soil. In galvanic couples of cold-bended steel EP/PC and Q235A steel EP/PC, PC is anode. Contact corrosion quickens the damage of thin-walled AP and small-area PC, leading the premature failure of prestress. The corrosion of the existing metal ends in pratical engineering should be improved.