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为研究先张法高强混凝土(PHC)管桩有效预压应力在制造、养护过程中的损失情况,对直径为1 400 mm、不同长度的两根PHC管桩进行了试验,并与理论计算结果进行对比。通过制桩过程中在桩身预应力钢棒上预埋电阻应变片,获得桩身不同截面的钢筋拉应力,继而探讨了不同阶段桩身预应力的分布及损失。试验结果表明,PHC管桩离心成型后预应力钢棒拉应力在张拉端处比锚固端大,沿管桩长度方向呈线性递减趋势;预应力钢筋有效拉应力和混凝土有效预压应力在张拉端较大、锚固端较小;两根管桩成型后预应力损失均在放张阶段最大;各截面测点的预应力分布具有一定的离散性,且随时间延长有增大趋势,而中部预应力分布最为均匀。
In order to study the loss of effective pre-stress of pre-tensioned high-strength concrete (PHC) pipe piles in the process of manufacture and maintenance, two PHC pipe piles with diameters of 1 400 mm and different lengths were tested and compared with theoretical calculation results comparing. Through the prestressed steel bar embedded in the prestressed steel bar during pile making process, the tensile strain of the steel bars in different sections of the pile body is obtained, and then the distribution and loss of the prestressed pile body in different stages are discussed. The test results show that the tensile stress of prestressed steel bar after centrifugal forming of PHC pipe pile is larger than the anchorage end at the tension end and decreases linearly along the length of the pipe pile. The effective tensile stress of prestressed steel bar and the effective pre-stress of concrete in Zhang The larger the tensile end and the smaller the anchorage end; the loss of prestressing force of the two pipe piles is the largest at the release stage; the prestress distribution of each cross-section measuring point has a certain degree of dispersion and tends to increase with time, Central prestressed the most uniform distribution.