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粉质粘土层在渤海海域分布广泛,渤海场地土层剖面中常常含有6层左右的粉质粘土层.目前国内对土层的阻尼比的不确定性对场地地震反应计算结果的影响的研究很少且局限于定性分析.基于敏感度分析的方法,本文提出了一种定量分析土层阻尼比对地表反应谱影响的方法并进行了数值实验.实验选取了渤海海域三个典型土层模型作为土层地震反应分析模型,通过控制影响土层地震反应计算结果的其他参量不变,赋予原阻尼比一系列的偏差,求出了地表反应谱及其相关参数的变化,进而得到了反应谱及其相关参数对阻尼比的敏感度.实验结果表明:(1)反应谱对粉质粘土阻尼比的敏感度一般小于0.4,在小震、中震、大震的地震动环境下,反应谱敏感度的高值区依次分布在0.04~0.2s、0.1~2.0s、0.2~3.0s之间,敏感度最大值依次为0.37、0.32、0.30;(2)特征周期和地震影响系数最大值对粉质粘土阻尼比的敏感度较小且一般后者的敏感度大于前者,数值实验中两者的敏感度最大值依次为0.13和0.21.
The silty clay layer is widely distributed in the Bohai Sea, and the silty clay layer in the soil profile of the Bohai Sea often contains about 6 layers of silty clay.At present, the research on the influence of the uncertainty of the soil damping ratio on the seismic response of the site is very Less and limited to qualitative analysis.Based on the method of sensitivity analysis, this paper presents a method of quantitatively analyzing the effect of soil damping ratio on the surface response spectrum and carries out numerical experiments.Experiments selected three typical soil model in the Bohai Sea as The soil seismic response analysis model, by controlling the other parameters that affect the calculation results of the soil seismic response, gives a series of deviations of the original damping ratio, and obtains the changes of the surface response spectrum and related parameters, and then obtains the response spectrum and The sensitivity of the related parameters to the damping ratio.The experimental results show that: (1) The sensitivity of the response spectrum to the damping ratio of silty clay is generally less than 0.4, and the response spectrum is sensitive to earthquakes with minor earthquakes, moderate earthquakes and large earthquakes The high-value areas are distributed in the order of 0.04 ~ 0.2s, 0.1 ~ 2.0s, 0.2 ~ 3.0s, and the maximum sensitivities are 0.37,0.32,0.30, respectively; (2) The maximum value of characteristic period and earthquake influence coefficient Sensitivity silty clay damping ratio is small and generally the sensitivity of the latter larger than the former, the maximum value of sensitivity in the two experiments were 0.13 and 0.21.