预应力钢筒混凝土管(PCCP)内层混凝土出现环状螺旋裂缝的现象较为普遍,有些裂缝在使用过程中遇水自愈不需要修补,而当裂缝宽度较大不修补时,裂缝会引起PCCP内置薄壁钢筒的锈蚀,形成事故隐患,为此开展了PCCP内层混凝土裂缝湿胀自愈原型试验研究,以期为PCCP内层混凝土裂缝宽度验收标准的制定提供依据.试件采用2根龄期分别为36 d和75 d的原型PC?CP,外径2864 mm、内径2400 mm、长度6000 mm,钢筒厚1.5 mm、直径2513 mm.试验时将PCCP试件置于试验井,观测在水中浸泡不同时间后内层混凝土裂缝闭合情况.根据测量得到的裂缝宽度改变值,推算出内层混凝土的湿胀速度、应变等.通过对试验结果的分析,得出防止内置钢筒锈蚀的PCCP内层混凝土表面裂缝控制宽度计算公式.%It is not unusual that spiral crack appeared in the inner layer concrete of Prestressed Concrete Cylinder Pipe(PCCP).Some of the cracks are self?healing without repair when used in water.However,when the crack width is increasingly larger without being repaired,it will cause the rust of the PCCP built?in?thin?walled steel tub,forming troubles of potential accidents. Accordingly,the experimental research on the PCCP of the inner layer concrete crack was carried out in order to provide the basis for the concrete crack width acceptance standard. The test specimens were come from two prototype PCCPs with the age of 36 d and 75 d respectively. The pipe length was 6 000 mm,with inner diameter of 2 400 mm and outer diameter of 2 864 mm. The diameter of steel tube was 2 513 mm with the thickness of 1.5 mm. The PCCP specimens were immersed in water well and the crack closure results of inner concrete layer were observed at different immersed time. The dilatation rate and strain of the inner concrete course were deduced by means of the measured crack width changes. Based on the experiment and results analysis,the calculating formula for the controlled width of surface crack in the inner concrete layer of PCCP was proposed to pre?vent steel tube from rusting.
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