南水北调中线总干渠漕河渡槽槽身为三槽一联加肋带拉杆的三向预应力结构形式。基于复杂施工条件下的预应力长期原位测试结果，对预应力的损失规律进行了分析，得到了预应力筋孔道摩阻系数 k ，μ值，不同孔道类型的锚具变形和预应力钢筋内缩引起的预应力损失和预应力钢筋松驰损失值，预应力张拉过程中孔道间影响效应，以及分步施工期间和加载过程中预应力历时损失。试验结果表明：瞬时损失的百分数与张拉应力的大小关系不密切；实测预应力损失值与按现行规范中确定预应力损失的方法计算结果有一定差异；锚具变形和预应力钢筋内缩在总损失中所占比重较大。此外，后续荷载作用和温度影响对预应力损失的影响较小可予以忽略。

The Caohe Aqueduct of the middle route of the South-to-North Water Diversion Project is a type of three troughs with multi-side walls and with three-dimensional prestressing structure. On the basis the long term field test of prestress losses for the rectangle aqueduct concrete structure, a detailed analysis of prestress loss was conducted. The values of the friction resistance coefficients k, μ were obtained. The duct-friction-loss and anchor-loss of various prestressed cable ducts of the aqueduct were analyzed. The losses of prestress due to the transmutation and retractation of the anchorage loop mouth and the losses of prestress due to tendon relaxation were analyzed as well. The stretching effect between the prestress tendon ducts, the duration losses at the construction period with special tensioning procedure and the loading process were analyzed too. The results show that the percentage of transient loss of prestress is not much relation to the stretching stress, that the measured results don ' t agree well with the calculated results to some extent, based on the actual Code for Design ； and that the losses due to anchorage deformation and retractation of tendons account for a large percentage of the total loss. Other factors that influence the prestress losses, such as temperature and subsequent loadings are discussed. In addition, the influence of subsequent loading and prestress losses temperature on prestress loss may can be ignored.