大流量薄壁渡槽槽身张拉工艺仿真研究

Simulation of Tension Process for High-flow and Thin-walled Aqueduct

沙河渡槽工程是南水北调中线的主要控制性工程,渡槽槽身为预应力钢筋混凝土梁式结构,单跨30 m,槽身U型,直径8 m,槽身壁厚35 cm,共228榀槽。槽身纵向预应力钢绞线27束,采用两端同时施加预应力方式,环向预应力初步设计119束,张拉施工量大,按老的张拉方法,待张拉全部完成后再将槽身起吊、移动,占用预制台座的时间长,必将严重制约槽身预制的施工进度,进而会影响整个渡槽工程的完工时间。研究项目通过建立张拉仿真模型,对渡槽预应力钢绞线的张拉施工顺序产生的应力场进行仿真研究分析,优化了环向预应力筋布置,优选出合适的张拉次序,采用分级、分步张拉方式,减少张拉工艺占用台座的时间,将大量张拉工作量放在存槽台座上完成,提高了预制效率及预制进度。

Shahe aqueduct is the main controlling project of the Middle Route of South-to-North Water Diversion Project. The aqueduct is the structure of prestressed reinforced concrete beam with single span of 30 m, U-typed body, diameter of 8m, wall thickness of 35cm, and 225 pieces of aqueduct body. There are 27 longitudinal prestressed steel strands within the aqueduct body, and the pre-stress shall be applied together at both ends. The aqueduct body has 119 circumferential pretressed steel strands in the preliminary design, and the tension work is heavy. According to the traditional tension method, the aqueduct could only be lifted and moved after the tension, which will take more time on precast pedestal, severely restricts the precast progress, and also affects the total completion time of the aqueduct. The current research project has built a simulation model of tension to simulate and analyze the stress field caused by the tension of pretressed steel strand, to optimize the layout of circumferential prestressed reinforcement as well as the suitable tension order. The tension by grade and step by step could shorten the time on pedestal and make more tension work to be finished by burden pedestal, so that the precast efficiency and progress could be improved and sped up.