Study on Time-Space Variations of Earthquake Waves Considering Non-Uniformity of Ground Surface Conditions

这项研究的目的是阐明地表条件对地震地面运动的影响。研究中考虑了不规则形状的地面，大量树木和建筑物按顺序排列在地面上。即使之前已经指出，地表不规则的地面可能会引起复杂的地震反应，但这种复杂反应的产生过程尚未得到澄清。在这项研究中，也对这一过程进行了研究。例如，对于不规则地表的影响，指出了不规则地表引起的复杂地震反应。然而，产生这种复杂反应的过程尚不清楚。在这项研究中，发展了边界元-摄动法来研究不规则表面对地震波的散射。该方法以频域边界元方法为基础，采用Neumann级数摄动技术。利用这种方法，可以将地面反应分解为入射波和散射波引起的反应。数值结果表明，散射波的幅度受不规则表面到观测点的距离和方向的影响。

The purpose of this study is to clarify the effects of the conditions of the ground surface on the earthquake ground motions. Irregular shaped ground, lots of trees and buildings, Which are existing ordinally at the ground surface, were considered in this study. Even if it has been pointed out previously that the ground with an irregular surface may cause complicated seismic responses, the process of generating this complex response has not yet been clarified. In this study, such a process was also examined.Regarding the effects of the irregular ground surface, for example, it has been pointed out that the ground with an irregular surface causes complicated seismic responses. However, the process of generating this complex response is not yet clarified. In this study, boundary element-perturbation method has been developed to investigate scattering of seismic waves due to an irregular surface. This method is based on the boundary element method in frequency domain and perturbation technique employing the Neumann series. By using this method, the ground response can be separated into those induced by incident waves and scattered waves. Numerical results showed that the amplitudes of the scattered waves are affected by both distance and direction of the irregular surface to the observation points.