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

作者:: 张照鹏¹; 荣棉水^2; 卢滔¹; 李红光³; (1.防灾科技学院,河北三河 065201; 2.中国地震局地壳应力研究所北京100085; 3.中国地震应急搜救中心工程勘测部,北京 100049)

Author(s):: ZHANG Zhaopeng¹; RONG Mianshui²; LU Tao¹; LI Hongguang³; (1.Institute of Disaster Prevention, Sanhe 065201, Hebei,China)(2.Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085,China)(3. Engineering Survey Department, National Earthquake Response Support Service, Beijing 100049,China)

Keywords:: horizontal-to-vertical spectral ratio(HVSR); strong earthquake observation; transfer function

摘要:: 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〖JB<1/〗(2α_B/β_B)^1/2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〖JB<1/〗(2α_B/β_B)^1/2在所考虑的频率范围内存在一定的弱相关性。

Abstract:: 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/(2α_B/β_B)^1/2, 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(2α_B/β_B)^1/2 in the frequency range considered.