SH-Waves in a Laterally Varying Medium : (1)The Seismic Response of Sediment-Filled Valleys to Plane-Incident SH-Waves
SH-Waves in a Laterally Varying Medium : (1)The Seismic Response of Sediment-Filled Valleys to Plane-Incident SH-Waves
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横向变化介质中的SH波：(1)沉积物山谷对平面入射SH波的地震响应
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发表时间：
1988
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影响因子：
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通讯作者：
T. Sasatani
中科院分区：
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作者：
T. Sasatani
我们应用Camplio和Bouchon(1985)提出的离散波数方法计算了平面入射波在横向变化介质中产生的SH波场。在对简单问题进行各种精度测试后，我们系统地研究了含沙河谷对平面入射SH波的响应。假设山谷由一层半空间组成，由一个周期余弦形状的界面隔开。边界曲率的主要作用是在倾斜界面上产生Love波，并将其捕获到山谷中。这种影响强烈地依赖于形状比(沉积物厚度与山谷半宽比)、沉积物与下伏基岩之间的速度差以及入射波场特征。对于具有高速度对比度的深谷，Love波在山谷边缘被有效地产生和反射，从而导致山谷内地面振动的较大放大和持续时间较长。这些结果表明，平面层理论对于计算可靠的地面运动似乎有很大的不足。
We applied the discrete wavenumber method proposed by Campillo and Bouchon (1985) to computation of the SH wavefield produced by incident plane waves in a laterally varying medium. After various tests of the accuracy of this method for simple problems, we systematically investigated the response of sediment-filled valleys to plane-incident SH waves. The valley was assumed to consist of a layer and a half-space separated by a one cycle cosine-shaped interface. The main effect induced by boundary curvature is the generating of Love waves on the dipping interface and their subsequent trapping inside the valley. This effect strongly depends on the shape ratio (sediment thickness to valley half-width ratio), the velocity contrast between the sediment and the underlying bedrock, and incident wavefield characteristics. For a deep valley with a high velocity contrast, Love waves are efficiently generated and reflected at the valley edges, resulting in a large amplification and in a long duration of the ground shaking inside the valley. These outcomes show that the flat layer theory appears strongly inadequate to compute reliable ground motions.