强震作用下大型渡槽结构地震动力破坏机理分析

Analysis on Seismic Dynamic Failure Mechanism of Large Aqueduct Structure under Strong Earthquake

为研究地震动力持时过程中大型渡槽结构在边界效应下的动力破坏机理及损伤发展历程,基于黏弹性边界理论,以南水北调某大型渡槽为例,将有限元软件ABAQUS与MATLAB程序结合,实现了黏弹性边界的施加;并通过引入混凝土塑性损伤本构模型,进行了抗震时域分析,验证了黏弹性边界效应对波动能量的吸收效果,确定了强震作用下渡槽结构易发生破坏的薄弱部位。结果表明:黏弹性边界对波的远域能量逸散有着良好的控制效果;强震响应下渡槽结构可能发生损伤破坏的位置主要集中于墩帽、墩身与墩帽衔接处以及承台与墩身连接处;随着地震力的持续作用,易发生损伤破坏的部位可能会引起损伤趋势的发展,进一步导致结构产生混凝土开裂现象;在渡槽结构的抗震设计中,为防止结构整体倒塌、破坏,应着重关注易发生损伤破坏的部位。

In order to study the dynamic failure mechanism and damage development process of large-scale aqueduct structure under the boundary effect in the process of seismic dynamic duration,based on the viscous-spring boundary theory,taking a large aqueduct of South to North Water Diversion Project as an example,the application of viscous-spring boundary is realized by combining the finite element software ABAQUS and MATLAB program.The concrete plastic damage(CDP)constitutive model is introduced,and the seismic time domain analysis is carried out to verify the absorption effect of vis-cous-spring boundary effect on wave energy,and the weak parts of aqueduct structure which are easy to be damaged under strong earthquake are obtained.The results are as follows.The viscous-spring boundary has a good control effect on the far-field energy dissipation of waves.The possible damage locations of aqueduct structure under strong earthquake response are mainly concentrated in the pier cap,the joint of pier body and pier cap,and the joint of pile cap and pier body.With the continuous action of seismic force,the parts prone to damage may cause the development of damage trend,and further lead to the phenomenon of concrete cracking.In the aseismic design of aqueduct structure,in order to prevent the collapse and destruction of the whole structure,it is necessary to pay more attention to the parts which are easy to be damaged.