基于粘弹性人工边界的岩质边坡地震反应分析

An Analysis of Seismic Response of Rock Slope Based on Viscous-Spring Artificial Boundary Condition

地震作用下,传统无质量固定边界模型没有考虑地基辐射阻尼,一般造成计算结果较实际偏大。通过对ANSYS有限元软件的APDL程序进行二次开发实现了粘弹性人工边界。对比粘性人工边界,该人工边界在动力分析中具有较高的精度和稳定性,且编程简单。同时,粘弹性边界条件下地震波输入的算例表明该条件下能够准确地模拟地震动输入。最后,将粘弹性人工边界用于地震作用下岩质边坡动力反应分析,研究与探讨了不同阻尼比下位移放大系数在坡体中的分布规律。研究结果表明:边坡的位移放大系数并不沿着高程而线性增加,而是先减小后增大,在坡体中下部形成一个极小值区。计算结果对边坡抗震设计具有一定的参考意义。

With earthquake action, the results derived from the no-mass foundation and fixed boundary model without conslderating the foundation radiation damping are usually larger than that in effect. The viscous-spring boundary is realized with the redevelopment of APDL of ANSYS finite element software. In dynamic analysis this boundary has highly computational precision and stability compared with viscous boundary, and it can be easily implemented by programming simply. An example of the input of seismic waves under the condition of the boundary demonstrates that this input is accurate and reasonable. The viscous-spring artificial boundary is applied to the dynamic analysis of rock slope with earthquake effect. Finally, the distribution of the displacement amplifi-cation coefficient in the slope is studied and discussed with varied damp ratios. The results show that the amplification of the displacement doesn＇t rise linearly with the elevation increasing but it first decreases and then increases and a region of minimum coefficient emerges at the low part of the slope. The results serve as a reference for the study of a seismic design of slope.