考虑黏结滑移的钢衬钢筋混凝土管道承载特性分析

基于三峡水电站钢衬钢筋混凝土压力管道实际工程和大比尺模型试验参数，建立了管道斜直段局部三维有限元数值分析模型，采用混凝土塑性损伤模型模拟管道外包及坝体混凝土，并在钢筋与混凝土界面插入内聚单元来模拟钢筋与混凝土之间的黏结滑移特性。钢筋分别采用埋入式和分离式两种模型，系统地研究了考虑黏结滑移以及黏结强度大小对管道承载特性的影响。结果表明，考虑黏结滑移以后，钢筋的应变和应力分布更为均匀，应力峰值减小，结构变形增大，使得钢衬应力稍有增加，但增加的幅度不超过10%。钢筋与混凝土之间黏结强度越大，管道上半周裂缝条数越多，平均裂缝间距减小，使得平均裂缝宽度越小。钢筋与混凝土的相对滑移量随着黏结强度的降低而增加，但均未超过规范允许值，表明钢筋与混凝土仍能保持良好的黏结而未发生黏结破坏。虽然考虑黏结滑移后的数值模拟结果与模型试验结果更为接近，但黏结滑移对管道结构整体承载安全性影响并不大，并且黏结滑移模型所需的计算工作量较大。因此，对钢衬钢筋混凝土管道这种环状封闭结构的受力特性进行有限元数值分析时，在设计中忽略其影响以简化计算，仍能够满足计算分析和工程设计复核的要求。

Study on the bearing characteristics of steel-lined reinforced concrete penstock considering the bond-slip behavior

Based on the actual engineering and large-scale model test results of steel-lined reinforced concrete penstock of Three Georges Hydropower Station, the local three-dimensional finite element numerical analysis model is established. A concrete damaged plasticity model is adopted to simulate the concrete damage characteristics and a cohesive element is inserted into the interface to simulate the bond-slip behavior between the concrete and reinforcement. The effects of the bond-slip between concrete and reinforcement and the bond strength on the bearing characteristics of penstock are explored by using two kinds of reinforcement models, namely, separate model and embedded model. The results show that:after considering the bond-slip, the strain and stress distribution of the reinforcement is more uniform, and the peak stress is smaller than the other two models. The structural deformation increases, which makes the stress of the steel liner slightly increase, but the increase is small, within 10%. The number of cracks in the upper of the penstock increases, and the average crack spacing decreases with the bond strength. The relative slip between the concrete and reinforcement increases with the decrease of the bond strength,but no more than the allowable value of the specification, indicating that the concrete and reinforcement can still maintain good bond condition without debonding. Though the numerical simulation results after considering the bond-slip are closer to the model test results compared with the other two models, the difference of the three models is small and the bond-slip behavior between the concrete and reinforcement has little effect on the safety of the composite penstock. Besides, considering the high computation and complexity of the bond-slip model, it is reasonable to ignore the bond-slip behavior to simplify the calculation when force analysis and structural design. As a result, for the closed composite penstock, the slip between the concrete and reinforcement is small to ignore in the design.