巨厚场地三种土层地震反应分析程序对比检验

Verification of three methods for calculating earthquake response of soil layers in deep sites

利用日本Ki K-net强震动观测台网数据库中巨厚土层的井下地震记录,对新研发基于频率一致等效线性化的一维土层地震反应计算方法 SOILQUAKE16以及当今国际上两种代表性一维土层地震反应计算方法 SHAKE2000和DEEPSOIL5.0在巨厚场地的可靠性进行对比检验。检验工况包括了土层厚度分别是215 m和148 m两个台阵,取其中地表峰值加速度不小于0.02 g的60台次水平地震加速度记录,地表峰值加速度范围为0.024~0.425 g,加速度峰值放大系数2.76~4.01。对比检验结果表明:烈度6度和7度偏下的较弱地震动下,SOILQUAKE16、SHAKE2000和DEEPSOIL5.0四个方法结果精度相当,计算出地表PGA与加速度反应谱均与实际较为接近,此时几种方法皆可采用;烈度7度中上、8度和9度的较强地震动下,DEEPSOIL5.0和SHAKE2000计算出的地表PGA较实际记录偏小,且随地震动强度增加与实测结果差距急剧增大,甚至小于井下输入,加速度反应谱"矮粗胖"不合理现象严重,不宜采用;而SOILQUAKE16计算出的地表PGA和反应谱均与实际记录相当,克服了以上弱点,可体现出深厚土层的放大作用,建议采用。SOILQUAKE16计算程序现已通过网络平台http://www.soilquake.org.cn提供共享服务。

Using the underground seismic records from the strong motion observation network database KiK-net in Japan, the three methods for calculating one-dimensional earthquake response analysis of soil layers in deep sites are verified. One of the methods is SOILQUAKE16 recently developed and the others are SHAKE2000 and DEEPSOILS. 0 used worldwide. The 60 horizontal seismic acceleration records no less than peak ground acceleration of 0.02 g are employed in two sites with depth of 215 m and 148 m, separately. The peak ground acceleration of these records are with a range from 0. 024 g to 0. 425 g and peak acceleration amplification factor of these recordings ranges from 2.76 to 4.01. The results indicate that there are similar accuracies of the calculated values by the above three methods under weak ground motion and the calculated values are near to the measured values both in the peak ground acceleration and surface acceleration response spectra. In the moderate and strong ground motion, however, the calculated values by SHAKE2000 and DEEPSOIL5.0 are obviously lower than the measured values and the gap between the calculated ones and the measured ones increases with the increasing of ground motion intensity, and e- ven lower than the downhole input values. By the contrast, the result of peakground acceleration and surface accel- eration response spectra by SOILQUAKE16 is close to the measured values, and can reflect the amplification effect of seismic ground motion in deep sites. The SOILQUAKE16 program is now available online http：//www. soilquake, org. cn.