地震作用下考虑地基土层构成的高耸式结构物动力有限元分析

Dynamic seismic stability analysis of erect structure considering soil stratigraphic

本文利用基于有效应力原理的有限元程序,计算了埋立在软弱成层地基上的高耸式结构物地震响应,重点考虑成层地基的土层构成对结构物地震稳定性的影响。结果表明:(1)地表土体为松散的冲填砂时,地震中产生砂土液化,极大的降低了地表承载力,高耸式结构物的埋深应适当增加;(2)地表土体为软弱的冲积黏土时,地震中并未产生液化破坏,但由于地表黏土层放大了地震波振幅,结构物摇晃剧烈,应着重验算结构物自身的抗弯刚度;(3)地表同为易液化的冲填砂、结构物埋深足够大时,还应考虑易液化层厚度,厚度较大的易液化层能够有效的减弱地表处地震波振幅,降低结构物的倾覆风险。

The seismic response of erect structures mainly focuses on the response of the structure itself without considering the effect of soil profiles. In this paper, the seismic stability of erect structures built on the multi-layer ground is investigated based on the finite element method and the emphasis is put on the influence of soil stratigraphic on the seismic responses of the structure. The results show that： （1） when the surface ground is loose sand, liquefaction occurs in this layer, which results in the great de- crease of the bearing capacity, and the embedded depth of the structure should increase; （2） when the surface layer is weak clay, there is no liquefaction in this layer. However, the seismic wave is greatly am- plified during this layer and the structure oscillates greatly. Therefore, the stiffness of the structure should be verified carefully; （3） when the thickness of the liquefiable layer is small, the attenuation of the accel- eration in the liquefiable layer is small, so the stability of the structure above is significantly reduced. This means, even when the soil of the surface layer on which the structure is installed is the same, the stability of the structure during the earthquake varies greatly depending on the differences in the stratigraphic composition.