Dynamic Behaviour and Identification of Non-Uniform Ground Using the Array Observation Records

我们开发了一种算法，以识别地面不规则性和它的材料特性，通过使用地震运动的阵列观测。识别是通过选择参数，以获得一个指定的频带之间的平滑的传递函数的振幅之间的最小二乘拟合计算从记录的加速度记录在两个观测点在地面上和相应的传递函数从我们的建模地面的动态响应。本文采用Powell的最小化多元函数而不计算导数的方法，构造了一个有效的算法，使其在有限次迭代中具有一定的收敛性，并在东京以北60公里的江户河附近的冲积层上建立了一个由四个记录站组成的观测系统。为了研究平面波在不规则界面上的散射，对观测点的地面剖面进行了建模。对于垂直入射 ...更多信息 因此，在一定的频率范围内，甚至在浅、深冲积层之间的过渡区，平层近似是可以接受的。当入射角较大时，由于入射波的相速度接近于在不规则层中传播的面波相速度，因此在相同的频率范围内，面波模式的产生更为明显.对于三个地震记录（Nos. 21，33和57），冲积层的剪切波速度，冲积层的深度和不规则区域的长度被指定为未知数。33级地震的加速度记录场地识别的这些参数值与实际值相当接近。与其他地震记录的实际参数的一致性不是很好，因为加速度水平不是很高。这里我们考虑P波和SV波作为入射波。少

We developed an algorithm to identify ground irregularity and its material properties by using an array observation of earthquake motion. Identification was made by choosing parameters to obtain a least square fit over a specified frequency band between the amplitude of the smoothed transfer function calculated from the recorded accelerograms at two observation sites on the ground surface and the corresponding transfer function obtained from the dynamic response of our modeled ground. Powell's method of minimizing a function of several variables without calculation of derivatives was used to construct an efficient algorism to make certain convergence in a finite number of iterations.An array observation system consisting of four recording stations was established on an alluvial layer close to the Edo River, 60km north of Tokyo. This ground profile for the observation points was modeled in order to investigate the scattering of plane waves at an irregular interface. For vertical inciden … More ce, a flat layer approximation is acceptable for certain frequency range, even for the transient region between the shallow and deep alluvial deposits. For a large incident angle, we found that the surface wave mode is generated more clearly in the same frequency range because the phase velocity of the incident wave approximates that of a surface wave propagating in a layer without irregularity.Our identification method was successfully used to analyze the accelerograms recorded at two observation sites on the ground surface. For three earthquake records(Nos. 21, 33 and 57), the shear wave velocity of the alluvium, the depths of the alluvium and the length of the irregular region were designated as unknowns. the values of these parameters for earthquake 33 identified from accelerograms sites were fairly close to the actual values. The agreement with the actual parameters obtained for other earthquake records was not so good because the acceleration levels are not so high. We here have considered P and SV waves as incident waves. Less