强震作用下肋拱式渡槽动力响应及损伤破坏机理研究

Dynamic Response and Damage Mechanism of Ribbed Arch Aqueduct under Strong Earthquake

为探究强地震作用下肋拱式渡槽结构的损伤破坏演化过程,以长岗坡渡槽为例,建立肋拱式渡槽结构三维非线性有限元模型,采用黏弹性人工边界方法来实现无限域地基的精准模拟,引入混凝土塑性损伤本构模型,开展不同地震强度作用下肋拱式渡槽结构的动力响应分析及损伤破坏模式的研究。研究结果表明:渡槽结构的动力响应随地震强度增大而增大;地震作用下,基于塑性损伤本构模型,通过模拟得到渡槽结构的峰值位移、峰值加速度响应均较线弹性本构模型模拟结果大,主要是因地震波的持续作用使结构出现塑性损伤,致使刚度退化;反之,峰值应力较线弹性模型结果小,主要是因结构出现的塑性损伤会导致结构阻尼增大,耗散能增大。渡槽整体结构损伤严重的部位为顺槽向靠近支墩位置的槽体、跨中肋柱以及支墩、肋拱、肋柱交界处,明晰了槽体、小腹拱、支墩等构件的损伤演化破坏演化过程,揭示了其主要是由结构受力不均而引发的混凝土受拉损伤破坏的损伤破坏机制。研究成果明晰了渡槽结构的抗震薄弱部位,可为类似渡槽结构的抗震设计及加固处理提供理论基础。

In order to explore the damage and failure evolution process of rib-arch aqueduct structure under strong earthquake,taking Changgang-slope aqueduct as an example,a three-dimensional nonlinear finite element model of rib-arch aqueduct structure was established.Viscoelastic artificial boundary method was adopted to achieve accurate simulation of infinite domain foundation,and a concrete plastic damage constitutive model was introduced.The dynamic response and damage modes of ribbed arch aqueduct structures under different seismic intensities are studied.The results show that the dynamic response of aqueduct structure increases with the increase of earthquake intensity.Based on the plastic damage constitutive model,the peak displacement and peak acceleration responses of the aqueduct structure are both larger than those simulated by the linear elastic constitutive model under the earthquake action,which is mainly due to the plastic damage of the structure caused by the continuous action of seismic waves,resulting in stiffness degradation.On the contrary,the peak stress is smaller than that of the linear elastic model,mainly because the plastic damage of the structure will lead to the increase of structural damping and dissipated energy.The serious damage of the overall structure of aqueduct is the channel body,the mid-span ribbed column and the junction of the support pier,ribbed arch and ribbed column.The damage evolution and failure evolution process of the components such as the channel body,the lower belly arch and the support pier are clearly defined,and the damage failure mechanism of concrete is mainly caused by the uneven stress of the structure.The research results clarify the seismic weak parts of aqueduct structure and provide a theoretical basis for the seismic design and reinforcement of similar aqueduct structures.