黏弹性人工边界等效荷载计算的改进方法

发布时间：2018-04-07 18:23

本文选题：地震波传播　切入点：数值模拟　出处：《力学学报》2016年05期

【摘要】：黏弹性人工边界在场地地震反应和结构-地基动力相互作用等问题的计算中已得到了广泛的应用.地震波在黏弹性人工边界中的输入是通过将地震波转化为作用于人工边界处的等效载荷来实现的.计算等效节点载荷的常规方法默认边界节点对应区域内的应力为均布力,但实际上该节点对应区域内的应力分布通常是不均匀的.本文在有限元方法结合黏弹性局部人工边界的显式时域波动方法的基础上,建立了无限域散射问题地震波等效载荷计算的一种改进方法.该方法采用细化网格与应力积分相结合的方法计算人工边界等效节点力,有效地降低了人工边界上等效节点力的计算误差.以不同角度入射地震波的二维算例为例,算例给出的波场位移云图和节点位移时程曲线验证了本文方法的有效性,其计算精度与网格尺寸和地震波入射角度密切相关,且网格越小、入射角度越小,计算精度越高.对于相同的网格尺寸,本文采用方法的计算精度明显高于常规方法,尤其是对于斜入射问题优势更为明显.
[Abstract]:The viscoelastic artificial boundary has been widely used in the calculation of site seismic response and structural-foundation dynamic interaction.The input of seismic wave in the viscoelastic artificial boundary is realized by transforming the seismic wave into an equivalent load acting on the artificial boundary.By default, the stress distribution in the corresponding region of the boundary node is uniform, but in fact, the stress distribution in the corresponding region of the node is usually uneven.On the basis of finite element method and explicit time-domain wave method of viscoelastic local artificial boundary, an improved method for calculating the equivalent load of seismic wave in infinite domain scattering problem is established in this paper.In this method, the equivalent node force of artificial boundary is calculated by the combination of thinning mesh and stress integral, and the calculation error of equivalent node force on artificial boundary is reduced effectively.Taking the 2-D example of incident seismic wave at different angles as an example, the displacement cloud map of the wave field and the nodal displacement time-history curve are given to verify the validity of the proposed method. The accuracy of the method is closely related to the mesh size and the incidence angle of the seismic wave.The smaller the mesh, the smaller the incident angle and the higher the accuracy.For the same mesh size, the accuracy of the proposed method is obviously higher than that of the conventional method, especially for the oblique incidence problem.
【作者单位】：南京工业大学岩土工程研究所;江苏省土木工程防震技术研究中心;中国地震局地球物理研究所;
【基金】：国家自然科学基金(41374049,51421005) 国家重点基础研究发展计划(2011CB013601)资助项目
【分类号】：P315.9

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