基岩倾角对盆地地震响应的影响分析

为了研究盆地基岩倾角对盆地地表动力反应的影响,选取了一个跨度2 km,深度500 m的二维成层盆地为研究对象进行有限元动力反应分析。以持时0.25 s的狄拉克脉冲作为输入地震动,探讨了P波和SV波垂直入射时,盆地基岩倾角从10°\,20°\,30°\,40°依次增加的情况下盆地地震反应。结果表明:入射波在倾斜基岩处发生波型转化,同时产生面波,在盆地中心区域发生汇聚;随着基岩倾角的增加地表中心处的卓越频率有减小的趋势。

Seismic Response of Basin Site under Plane Wave with Different Bedrock Inclinations

To analyze the dynamic response at the surface of a basin site under seismic waves with different bedrock inclinations, a 2D layered basin with a depth of 100 m and width of 2 km was selected. Under the input of a Dirac pulse with a duration of 0.25 s, the seismic responses of the basin subjected to vertical incident P wave and SV wave were analyzed with bedrock inclinations of 10°, 20°, 30°, and 40°. The result shows that the incident wave had a wave-type transformation at the inclined bedrock; meanwhile, surface waves were generated and were concentrated at the center area of the basin. With increase in the bedrock inclinations at the valley sides, the dominant frequency at the center of the earth surface tended to decrease. The results obtained from the present analysis can provide a reference to research on this topic.