重力坝地震波动的时域数值分析

Numerical analysis of seismic wave-motion of gravity dam in time domain

传统的重力坝地震响应分析模型未考虑地基辐射阻尼的作用以及波动的不均匀输入．为此，将黏-弹性人工边界条件应用于重力坝地震响应分析中，并基于波场分离技术推导了地震波从底面垂直入射时的重力坝波动输入公式，同时探讨了地基弹性模量对地基辐射阻尼的影响．计算结果表明，黏-弹性边界下的动应力值比固定边界无质量地基下的动应力值小20％-40％，并且地基弹性模量越小，峰值动应力降幅就越大．

In conventional model for dynamic response analysis of gravity dams, the effect of foundation radiation damping and inhomogeneous input of wave motion have not been taken into account. In this paper, the visco-spring artificial boundary condition was introduced into the dynamic response analysis of gravity dams. A wave-motion input expression for seismic waves vertically incident from the bottom of gravity dams was deduced based on the technique of wave field separation, and the effect of elastic modulus of dam foundation on its radiation damping was studied. Calculation result shows that the dynamic stress of dam on the foundation with the visco-spring artificial boundary is 20% - 40% less than that on the massless foundation with fixed boundary, and that the peak value of dynamic stresses decreases evidently with the decrease of the elastic modulus of dam foundation.