硬场地实测记录下几种土层地震反应分析程序可靠性对比

Verification of several programs for calculating earthquake response of soil layers in hard sites based on ground-motion records

以日本Ki K-net强震观测台网中硬场地井下记录为样本,对传统等效线性化方法 LSSRLI-1(频域)、SHAKE2000,时域非线性方法 DEEPSOIL和频域一致等效线性化方法 SOILQUAKE等几种计算程序在硬土场地地震反应分析中的可靠性进行对比检验。检验工况包括Ki K-net井下台网中地表峰值加速度不小于0. 05g的水平硬场地的总计344台次的加速度记录,涉及5个台站,土层厚度6~50m,地表峰值加速度范围0. 050~0. 805g。结果表明:认为硬土场地以往计算方法能够体现土层放大的认识是片面的,在中强地震动情况下,现有流行方法计算出的地表响应会偏小,强地震动下会严重偏小,会给工程抗震设计提供偏于危险的输入;硬场地中烈度8度以下(地表PGA在0. 19g以下),SHAKE2000和DEEPSOIL、LSSRLI-1(频域)计算结果与实际记录差距可以接受,但烈度8度以上,计算出地表响应均较实际记录明显偏小,且随地震动强度增加差距急剧增大;硬场地中,无论何种烈度,SOILQUAKE16计算的地表加速度响应与实测相当,可体现出土层放大作用。

Using ground-motion data from KiK-net strong earthquake observation network in Japan, the reliability of SHAKE2000 used the traditional equivalent linear method, DEEPSOIL used the time domain nonlinear method and SOILQUAKE used the frequency-consistent linear method in the seismic response analysis for the hard site are compared and tested. In the analysis, a total of 344 acceleration time histories with both peak ground acceleration （PGA） not less than 0.05g and a PGA range of 0.050g to 0. 805g from 5 stations with soil layer thickness from 6m to 50m were utilized. The results show that the previous calculation method can reflect the understanding of soil amplification is one-sided, and in the case of moderate-strong ground motion, the ground response calculated by the existing popular methods will be small, and under strong ground motion, it will be smaller, which will provide dangerous input for engineering seismic design. When the earthquake intensity is below VIII （ PGA below 0.19g）, the results calculated by the above three programs are close to the measured ground acceleration responses. However, when the earthquake intensity is above VIII （PGA above 0.19g）, the ground acceleration responses calculated by the programs are obviously smaller than the measured those, and with increase of PGA, the differences between re- suits calculated and measured increase sharply. No matter what the earthquake intensity is, the ground acceleration response calculated by SOILQUAKE16 is equivalent to the measured those, which can reflect the amplification effect of soil layer.