浅硬场地剪切波速测试标准差对地震动影响初探

采用Shake 2000程序,以Turkey Flat试验场地为模型,通过输入不同类型下多种强度的地震波,计算研究多工况下剪切波速测试标准差对地表加速度反应谱和峰值加速度的影响。结论为:(1)浅硬场地上剪切波速测试标准差对地震动的影响很大,影响程度与输入地震波的强度和频率以及场地剪切波速计算值有关;(2)如果将反应谱残差大于20%或加速度峰值差别大于20%定义为统计意义上的不可忽略,那么剪切波速测试标准差对计算结果的影响在大多数情况下均不可忽略;(3)当输入波的卓越周期与场地特征周期接近时,浅硬场地上剪切波速测试标准差引起的反应谱变化非常显著;(4)只有当输入波的卓越周期与场地特征周期相差较大且输入波强度偏小时,剪切波速测试标准差引起的反应谱变化才可略去;(5)当浅硬场地上剪切波速实测结果低于统计均值时,地震动计算结果的偏差一般明显大于剪切波速实测结果,高于统计均值时引起的偏差,且地震输入越强表现越明显。

Influence of the Shear Wave Velocity Test Standard Deviation onGround Motion at a Shallow Stiff Site

This study addressed the influence of the shear-wave velocity test standard deviation on ground motion.The Shake 2000 program and site model of Turkey Flat were used to analyze the response spectrum of ground and peak acceleration under a variety of engineering conditions by inputting different types of multi-intensity seismic waves.The study concluded the following:(1)the impact of the shear wave velocity test standard deviation on ground motion in the shallow stiff soil site is related to the intensity and frequency of the input seismic waves, and the calculated value of shear wave velocity;(2)if the response spectrum residuals or peak acceleration D-value exceed 20%, the effects of the velocity test standard deviation cannot be ignored in most situations;(3) when the predominant period of the input ground motion is similar to the characteristic site period, the changes of the response spectrum caused by the shear wave velocity test standard deviation in the shallow stiff soil site is significant;(4)only when the predominant period of the input ground motion with weak intensity and the characteristic site period are largely different, can the changes in the response spectrum caused by the test standard deviation be omitted;and (5)if the shear wave velocity in the shallow stiff soil is lower than the statistical mean value, the calculated value deviation of ground motion is larger than the measured value of shear wave velocity which is higher than the calculated mean value, and the ground response is more obvious with higher intensity of the input ground motion.