葛洲坝护坦新旧混凝土粘结面水压力分布规律研究

Research on Hydraulic Fluctuating Pressure Distribution Between New and Old Concrete Binding Surfaces on Gezhouba Dam's Apron

葛洲坝护坦底板修补材料极易被高速水流冲蚀破坏,影响大坝安全稳定运行。根据护坦底板新浇筑材料与旧混凝土粘结面缝隙脉动水压力的分布规律,建立了接触面缝隙脉动压力传播的两个阶段即渗流和瞬变流阶段的数学模型,并对实际工况进行了模拟计算。结果表明,闸室底板粘结面水压力在渗流条件下,沿程各点脉动水压力频率与尾部的原生脉动压力频率保持一致,沿程各点脉动水压力振幅与x/L成正比;在瞬变流条件下,粘结面中部点的脉动水压力由与尾部点原生脉动压力相似的低频脉动和间杂在整个过程中的高频脉动组成;沿程阻力系数对缝隙水压力的影响主要体现在对高频脉动的削弱;渗流条件下其振幅沿程增大,在瞬变流条件下,各点脉动压力振幅沿程分布变化不明显。修补材料粘结面的疲劳破坏属于应力疲劳,修补材料整体揭底冲毁为其中的破坏形式之一,整体揭底破坏与新旧材料之间粘结面疲劳损伤关系密切。

The repair material on Gezhouba dam＇s apron slab is easy to be damaged by the high speed flow from the spillway, which would impact on the normal operation of the dam. Here, based on the hydraulic fluctuating pressure distribution between the new and old materials, the mathematical models in two stages for pressure transmission are set up, such as the seepage flow stage and the transient flow stage, at the same time, the modelling and computation are made for the actual conditions. The resuits show that the fatigue damage between the binding surfaces belongs to the stress fatigue, and the monolithic washing damage is in close relationship with the fatigue damage between the binding surfaces.