基于黏弹性人工边界的拱坝动力响应分析

无限地基的辐射阻尼是影响拱坝地震反应的一个重要因素,无限边界的处理方法很多,其中黏弹性人工边界具有较高的计算精度和计算效率、较好的稳定性,同时程序容易实现。基于黏弹性人工边界的基本原理,以Ansys为计算平台,采用声学流体单元fluid30模拟库水,在坝基截断边界添加弹簧-阻尼单元以考虑无限地基的辐射阻尼影响;并以锦屏一级高拱坝在El Centro地震波作用下的动力响应分析为例,对不考虑坝基辐射阻尼与采用黏弹性人工边界两种计算方法的计算结果进行比较。结果表明,采用黏弹性人工边界条件后的动力响应(动水压力、位移、主应力)均有所降低,坝顶拱冠处的应力分布更为合理,动力响应时程滞后;验证了该边界条件的吸能效果。该方法计算效率高、稳定性好,克服了透射边界与有限元相结合的方法存在高频失稳问题的缺陷。

Seismic Response Analysis of Arch Dams Based on Viscous elastic Artificial Boundary Condition

The radiation damping of unbounded foundations is an important factor to the seismic response of arch dams.There are many methods to process the unbounded foundations,among which the method of the viscous-elastic artificial boundary condition has a higher computational precision,higher computational efficiency and better stability.Meanwhile,it is easy to program.Based on the basic theory of viscous-elastic artificial boundary condition and Ansys software,the reservoir is simulated by using the acoustic fluid element fluid30,and the spring-damping elements are added to the truncated boundary of dam foundation to consider the influence of radiation damping.The seismic response of Jinping high arch dam under the El Centro earthquake wave is analyzed by this method and another one which could neglect the radiation damping of dam foundation.The results show that the energy absorption effect of this boundary condition is better.