【摘要】 美国阿拉斯加安克雷奇德兰尼公园的土层地震反应观测台阵建有6个井下观测点和1个地表观测点,每个观测点设置一个三分量加速度传感器,该台阵建成后记录了多次地震事件.本文通过反卷积地震干涉法对这些地震记录进行土层反应分析,根据该分析结果提取土层结构的等效剪切波速和阻尼比.所有层位的地震记录对地表记录的反卷积波形均反映出在土层中传播的上、下行波,其上行与下行至每一层的时间差别明显.根据每一层的到时差,确定土层中的等效剪切波速和分层等效剪切波速,该结果与现场土层等效剪切波速测试结果吻合较好;根据等效剪切波速计算出的土层卓越频率,其一致性亦较好;根据上、下行波的峰值分析确定该场地土层的等效阻尼比,也与软土的阻尼比经验值相当.这些参数为后续的土层反应模拟和土结相互作用研究奠定了良好的数据基础.结果表明,反卷积干涉法能够用于土层反应分析和土层地震反应特性的提取.更多还原

【Abstract】 Seismic interferometry technique was used to extract the shear wave velocity and damping ratio of the soil at the Delaney Park,Anchorage Alaska from the measured soil response to ten earthquakes.The soil response is recorded by ageotechnical array.This array consists of a surface and six borehole stations equipped with a tri-axial accelerometer each.Deconvolution of the waveforms recorded by the borehole accelerometers at various depths with the waveform recorded at the surface accelerometer manifests an upward and a downward travelling wave in the soil.The arrival times to each accelerometer are obvious so that the entire travel time and time differences are extracted from the deconvolved waveforms.The shear wave velocity and its profile estimated from the deconvolution analysis agree reasonably well with in-situ measurements.The predominant frequencies are also inferred from the shear wave velocity and they are basically consistent for the ten earthquakes.The damping ratio is similarly investigated from the amplitude attenuation of the upward and the downward travelling waves.The value of damping ratio coincides with the empirical damping ratio of the soft clay as well.Analysis indicates that wave deconvolution can be used to extract the soil response and its characteristics.更多还原