选取新西兰Canterbury地区12个强震台站及2010—2012年间的台站584条记录，以浅硬场地LPCC作为参考台站，系统分析Christchurch市区软厚场地地震效应(即场地放大函数)的不确定性及地震动强度、震级、震源距及震源方位角等因素对场地放大函数不确定性的影响规律。分析结果发现：1)地震动强度水平对场地放大函数均值影响较小，仅在长周期(如大于1.0 s)段趋于增大场地的放大效应；以不同地震动强度值进行分组，地震动强度大于0.6 m/s 2的分组场地放大函数标准差显著高于地震动强度小于0.6 m/s 2分组，特别是地震动强度大于1.0 m/s 2时场地放大函数标准差最大，反映了场地土层非线性提高场地地震效应的不确定性；2)地震震级对场地放大函数不确定性影响小，不同地震震级分组场地放大函数均值及标准差的表现基本相当；3)震源距是场地地震反应不确定性的一个重要因素，震源距小于5 km时场地放大函数的标准差明显大于其它情况，即震源距越小地震反应不确定性越大；4)场地放大函数不确定性与震源方位角的选取基本无关，即选取不同的震源方位角场地放大函数标准差无明显差别。

12 strong-motion stations are selected and based on 584 seismic records recorded during the 2010-2012 Canterbury earthquake sequences, New Zealand, a systematic variability analysis of the deep-soft site response (SAF, i.e., site amplification function) in Christchurch city area is conducted with a reference outcropping station LPCC. Thereafter, influence factors including ground motion intensity roughly measured by PGA, magnitude Mw, hypocentral distance Rhypo and azimuths on the variability of SAF are analyzed. The results show that: 1) ground motion intensity PGA has weak effect on mean lg(SAF) values except that PGA tends to strengthen amplification effect for long period components; while under different PGA subdividing bins, the standard deviations of lg(SAF) for bins with PGA greater than 0.6m/s2 are considerably larger than those for PGA less than 0.6m/s2 bins, indicating possible subsoil non-linearity tends to increase the site response variability; 2) seismic magnitude shows little influence on the variability of site response and the means and standard deviations of log10(SAF) for different Mw dividing bins demonstrate similar patterns; 3) hypocentral distance is an another important influence factor on site response variability, that is, the variability of SAF with Rhypo less than 5km is larger than that with Rhypo were larger than 5km; 4) the variability of SAF is basically independent of source azimuths to stations which means the uncertainty of SAF remains closely similar in different azimuth bins.

黑龙江省自然科学基金(LC2013C14)