大型预应力梁式渡槽应力变形监测与仿真分析

Analysis of Monitoring and Simulation of Stress and Deformation of Large Scale Prestressed Beam Aqueduct

沙河渡槽是南水北调中线建设的关键性工程,采用预制吊装的U形梁式渡槽结构形式,体型巨大、受力情况复杂,其施工和运行的安全性对南水北调中线建设具有重要影响。通过渡槽监测方案设计,监测渡槽跨中截面底部纵向钢筋应力及渡槽应变值,考虑渡槽在1 a监测期内温度变化的影响。采用有限元法建立渡槽在施工期和运营期的有限元计算模型,将有限元计算结果与施工期渡槽纵向钢筋应力和渡槽应变的监测结果进行对比分析,验证有限元模型的正确性。利用有限元计算模型分析了渡槽在运营期应力和位移分布规律,给出了渡槽应力和位移的变化云图,研究了渡槽关键截面内表面的应力变化曲线。结果表明,运营期渡槽在纵向和环向预应力作用下内表面基本为压应力,满足抗裂设计要求;渡槽竖向变形很小,满足刚度设计要求;有限元仿真分析结果验证了渡槽结构设计和施工方案的合理性。

Shahe River aqueduct is a key project in the Middle Route of South-to-North Water Diversion Project,which adopts the structure form of U-shaped beam aqueduct with prefabricated lifting.The aqueduct is characterized by its huge structure and complex stress condi⁃tions,so the safety of the construction and operation plays an important role in the water diversion project.The monitoring scheme of aqueduct was designed during the construction period.The longitudinal reinforcement stress and aqueduct strain values at the bottom of the mid-span section of the aqueduct were obtained through monitoring and the effect of temperature change during one year monitoring period was consid⁃ered.The finite element model of aqueduct in construction period and operation period was established by using finite element method,and the finite element calculation results were compared with the monitoring results of the longitudinal reinforcement stress and strain in the aque⁃duct during the construction period.The analysis results verified the correctness of the model.The distribution law of stress and displacement of aqueduct during operation was analyzed by using finite element model.The nephogram of stress and displacement of the aqueduct were giv⁃en and the stress curve of the key section of aqueduct was studied.The results show that under longitudinal and circumferential pre-stressing,in the operation period,the internal surface of the aqueduct is basically compressive stress,which meets the design requirements of anticrack of the aqueduct;The vertical deformation of aqueduct is very small,which meets the design requirements of aqueduct stiffness.The re⁃sults of finite element simulation verify the rationality of the design and construction scheme of the aqueduct structure.