HVSR谱比法应用于强震数据时基本假定合理性讨论

Discussion on Rationality of Basic Assumptions When Applying HVSR Method to Strong Earthquake Data

采用日本KiK-net台网中9个台站的实测场地模型及多个地震的强震观测记录等数据,对HVSR方法应用于强震数据时“基岩处水平-竖向谱比为1”的假定进行了讨论,并探讨了利用不同系数计算场地水平传递函数TF H的差异,最后对表征不同TF H差异的系数进行了相关性分析。结果表明:强震观测数据揭示的基岩内水平-竖向谱比不一定为1,仅在某一频率范围内可以视为一个常数;表征用不同TF H差异的系数C取为1/√2αB/βB时,计算得到的水平向传递函数与实际观测得到的水平向经验传递函数一致性较好;HVSR B与1/√2αB/βB在所考虑的频率范围内存在一定的弱相关性。

Firstly,using the measured data of 9 stations in the Japan KiK-net network and the strong earthquake observation records of several earthquakes,we discussed the assumption that‘the horizontal-vertical spectral ratio of bedrock is 1’when HVSR method is applied to strong earthquake data.Secondly,on this basis,we calculated the differences between the TF H of the site horizontal transfer function by using different coefficients.Finally,the correlation coefficients of the TF H differences calculated by different formulas are analyzed.The results show that the horizontal-to-vertical spectral ratio in the bedrock revealed by the strong earthquake observation data is not necessarily 1,and can be regarded as a constant only in a certain frequency range.When the coefficient C which is used to estimate the difference of TFH with different formulas is taken as 1/√2αB/βB,the theoretically calculated horizontal transfer function is in good agreement with the actual observed horizontal transfer function.There is a certain weak correlation between HVSRB and√2αB/βB in the frequency range considered.