硬夹层埋深对场地地震动参数的影响

Influence of the Buried Depth of Hard Interlayer on Ground-motion Parameters

选取某重要工程场地A3钻孔的厚度、剪切波速、密度等实际勘探数据,通过改变硬夹层的埋深,分析硬夹层不同埋深、不同地震时程对场地地震动参数的影响。研究结果表明:在硬夹层厚度不变和模型总厚度不变的情况下,地表水平向的峰值加速度随硬夹层埋深的增大而增大,但增幅逐渐减小;硬夹层埋深到达一定深度时不再影响地表水平峰值加速度;随着硬夹层埋深的增加,整个反应谱的谱值普遍增大。

Ground motion characteristics are seriously influenced by local site conditions,and in recent years,one of the hot spots in the field of earthquake engineering has been the impact of a hard site interlayer on ground motion characteristics.This paper selects the thickness,shearwave velocity,density,and other actual exploration data from borehole A3 in a certain project site by changing the buried depth of the hard interlayer to analyze the influence of depth and different seismic time history data on ground motion parameters.In this paper,a one-dimensional seismic response analysis of a typical site with a hard interlayer was conducted by using the time domain nonlinear method.Research has shown that when the thickness of the hard interlayer and the total thickness of the model remain invariable,the surface horizontal peak-ground acceleration increased with the buried depth of the hard interlayer,but its amplification reduced gradually,until it was no longer affected when the hard interlayer's buried depth reached a certain value.Furthermore,as the buried depth increased,the values of the response spectrum generally increased.From the surface Fourier spectrum diagram,we found the spectrum values were small and flat in the range of 0~0.2 Hz,and then increased gradually to a range of 0.2~1 Hz.Spectrum values peaked and then reduced again in the range of 1~1.5 Hz.Spectrum values hit the second peak in the range of 1.5~5Hz,and then dropped down after 5Hz.For the Fourier spectrum at different buried depths,spectrum values didn't change much in the range of 0~1 Hz.These results will provide an important reference for the seismic design of deep foundation pit engineering such as nuclear power station and underground engineering.