论文部分内容阅读
提出了一种改进的考虑非线性场地效应的概率地震危险性分析方法。文中应用实例展示了考虑吉尔罗伊2号场地土层非线性效应的危险性曲线。在卡拉韦拉斯断层上指定了震源参数和地震发生模型,假设该断层为影响该场地的主要震源。采用3次地震的记录经NONLI3程序(可计算土层对强地面运动的非线性响应)建立了该处地表和基岩加速度之间的关系。对一定的基岩运动,估算出的地面峰值加速度(PGA)标准误差的不同值可作敏感性分析。实例研究中包括一个可替换的非线性关系。除了非线性模型,在吉尔罗伊2号场地上的相同土壤剖面也采用了线性响应模型。结果显示,危险性曲线对估算的该处地表加速度峰值的标准误差非常敏感。如果对场地土壤的非线性程度考虑不足,危险性曲线将严重失真。得自回归分析的可替换的非线性模型和线性响应模型在考虑非线性场地效应的危险性评估时是不适用的。
An improved method of probabilistic seismic hazard analysis considering nonlinear field effects is proposed. The application example shows the danger curve considering the nonlinear effect of soil in Gilroy 2 site. The source parameters and the earthquake occurrence model are specified on the Calaveras fault, assuming that the fault is the main source of the impact on the site. Using the NONLI3 program, which calculates the nonlinear response of soil to strong ground motions, records of three earthquakes establish the relationship between the surface and bedrock acceleration there. For a given bedrock motion, different values of the estimated standard deviation of ground acceleration (PGA) can be used for sensitivity analysis. The case study includes a replaceable non-linear relationship. In addition to the non-linear model, a linear response model was used on the same soil profile at Gilroy Field 2. The results show that the hazard curve is very sensitive to the estimated standard error of the surface acceleration peak at this site. If insufficient consideration is given to the degree of soil non-linearity, the hazard curve will be severely distorted. Alternative nonlinear models and linear response models from regression analysis are not applicable when considering the risk assessment of nonlinear site effects.