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1 前言 近来发生的许多地震表明,地震场地条件对地面运动可以产生显著的影响。对线性和非线性土,用一维和二维模型进行了许多考虑软土层影响的有关地面运动修正的研究。虽然对一维模型能否用来预测软土场地长持时地面运动这一点尚可探讨,但该模型在预测有二维和三维效应的软土场地的地面运动峰值和反应谱方面已得到了许多成功的应用。一个例子是对墨西哥城软土场地的分析。Seed等利用基岩场地附近的记录作为输入,采用等效线性法拟合了土层场地上的记录反应谱;Hadley等用二维模型产生的基底运动作为一维非线性模型的输入,预测了土层地表反应。一般认为,墨西哥城的二维和三维效应是显著的,然而就工程应用来说,一维模型的效果是得到了确认的。一维模型由于简单,且所得结果易于解释,因此在工程应用中仍然是最广泛选用的模型。二维模型也可以用来求场地反应特性与土层物理参数间的简单关系。
1 Introduction Many recent earthquakes have shown that seismic site conditions can have a significant impact on ground motion. For linear and nonlinear soils, many ground motion correction studies that consider the effects of soft soils have been conducted using one-dimensional and two-dimensional models. Although the one-dimensional model can be used to predict the long-term ground motion at soft soil sites, this model has been discussed in predicting ground motion peaks and response spectra of soft soil sites with two-dimensional and three-dimensional effects. Many successful applications. One example is the analysis of soft soil sites in Mexico City. Seed et al. used the records near the bedrock site as input, and used the equivalent linear method to fit the record response spectrum on the soil layer; Hadley et al. used the base motion generated by the 2D model as the input of the 1D nonlinear model, and predicted that Soil surface reaction. It is generally believed that the two-dimensional and three-dimensional effects of Mexico City are significant, but in terms of engineering applications, the effects of one-dimensional models have been confirmed. Since the one-dimensional model is simple and the results are easy to interpret, it is still the most widely used model in engineering applications. The two-dimensional model can also be used to find a simple relationship between site response characteristics and soil physical parameters.