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采用黏弹性人工边界并结合地震动输入等效结点力法实现半无限场地的波动输入,采用等效线性法模拟土体的非线性特征,基于有限元软件ABAQUS,建立弹性基岩上覆深厚软土中三维凹陷地形非线性地震响应分析模型。通过与文献比较,验证了整体模型的精度。以天津地区某一浅椭球凹陷地形为例进行数值计算,比较了非线性地震响应与线性地震响应的差别,并进一步分析了三维凹陷地形对非线性地震响应造成的影响,最后计算了在地震安全性评价人工波作用下三维凹陷地形的非线性地震响应。研究表明,土体的非线性特征对三维凹陷地形地震响应有显著影响。研究还发现一个特殊现象,即凹陷地形中心附近的非线性地震响应可能会大于其线性地震响应,且地震激励幅值越大,这一现象越明显。对于三维复杂局部场地的非线性地震响应研究,模型具有一定的参考价值。
The viscoelastic artificial boundary is used in combination with the input equivalent node method of ground motion to realize the wave input of semi-infinite field. The equivalent linear method is used to simulate the nonlinear characteristics of soil. Based on the finite element software ABAQUS, Nonlinear Seismic Response Analysis Model of 3D Depression in. Through the comparison with the literature, the accuracy of the overall model is verified. Taking a shallow ellipsoid depression terrain in Tianjin as an example, the difference between the nonlinear seismic response and the linear seismic response is compared. The effect of the three-dimensional depression terrain on the nonlinear seismic response is also analyzed. Finally, Nonlinear seismic response of three dimensional depressed terrain under safety evaluation of artificial wave. The research shows that the nonlinear characteristics of soil have a significant effect on the seismic response of three-dimensional depression terrain. The study also found that a special phenomenon is that the nonlinear seismic response near the center of the depression terrain may be greater than its linear seismic response, and the more the seismic excitation amplitude is, the more obvious this phenomenon is. For the study of nonlinear seismic response in three-dimensional complex local sites, the model has certain reference value.