峡谷地形隔震效应及减灾选线对策

在困难山区,峡谷是铁路、公路常利用的交通廊道,但峡谷往往也是震害集中的地段,目前有关峡谷地形对地震波传播特性的影响研究甚少。基于波动理论,分析得出峡谷切割深度越深,对Rayleigh波高频成分的屏蔽频率范围越广;峡谷越陡,对散射波的强度削减效应越显著;从而地震波的强度在峡谷两侧具有显著的差异,即在地震波入射一侧的振动强度大于另一侧。上述结论得到了芦山地震震害现象以及苏克拉峡谷地震记录仪观测资料的检验,可为减灾选线设计提供理论依据。

Effect of Valley on Ground Motion and Disaster Reduction in Route Selection

In rugged mountainous area,valleys are usually used as transportation corridors for railway and highway. But valleys are places where seismic hazards are prone to occur. At present,there is less research on the characteristics of wave propagation over a valley. Based on the wave theory,the following conclusions are made. The deeper a valley,the wider the high frequency shield range of Rayleigh wave.The steeper the valley,the more significant the scattered wave attenuation. The intensity of seismic waves on the two sides of valley slopes differs greatly. The ground motion on the wave incident side is stronger than the other side. Above conclusions are validated by Lushan earthquake and the data recorded by seismograph at Sulak valley,which may provide a theoretical basis for disaster reduction in route selection.