基于复合方法的天水盆地宽频带地震动模拟

发布时间：2018-06-03 11:51

本文选题：天水盆地 + 设定地震　；参考：《地质力学学报》2017年06期

【摘要】：本文采用有限差分和随机振动合成结合的复合方法,模拟了当礼县—罗家堡断裂发生矩震级Mw7.7级大地震时,在天水盆地产生的宽频带地震动场,分析了在设定地震条件下盆地内的地震动分布特征,为该区黄土地震滑坡分析提供了地震动参数结果。结果显示:(1)有限差分法和随机振动合成法可以很好地互补,得到盆地内地表宽频带地震动;(2)地震在盆地区域产生了强烈地震动,PGA(峰值加速度)介于150~900 gal,离断层较近的区域东南角的PGA最大,随着断层距的增加,PGA逐渐减小。河谷南侧的PGA值相比北侧较大,具备诱发滑坡的强大动力条件;(3)盆地区域PGV(峰值速度)最大为120 cm/s。受第四系覆盖层放大效应和地形放大效应共同影响,水平向地震动在盆地区域东侧和中部具有较大PGV,而西侧PGV相对较小。竖向地震动在盆地区域东侧较弱,而在中部和西侧较强,特别是最西侧陡峭的山坡上,PGV达到了最大值。此外,竖向地震动明显受到覆盖层厚度的影响,譬如在盆地区域南侧的中间部位,也具有较大的PGV。
[Abstract]:In this paper, the composite method of combining finite difference and random vibration synthesis is used to simulate the wide-band ground motion field in Tianshui Basin when the Lixian-Luojiapu fault has a moment magnitude Mw7.7 earthquake. The characteristics of ground motion distribution in the basin under given earthquake conditions are analyzed, and the results of ground motion parameters are provided for the analysis of loess earthquake landslide in this area. The results show that the finite difference method and the random vibration synthesis method can complement each other well. It is found that the wide band ground motion in the interior of the basin caused strong ground motion (peak acceleration) between 150 and 900 gals. the PGA in the southeastern corner of the area near the fault is the largest, and gradually decreases with the increase of fault distance. The PGA value in the south side of the valley is larger than that in the north side, and the maximum value of PGA (peak velocity) in the basin is 120 cm / s. The horizontal ground motion has larger PGVs in the east and middle of the basin, but the PGV in the west side is relatively small under the influence of both the overburden effect of Quaternary system and the topographic amplification effect. The vertical ground motion is weak in the east side of the basin area, but stronger in the middle and west side, especially on the steep hillside of the westernmost side. In addition the vertical ground motion is obviously affected by the thickness of the overburden such as in the middle part of the southern side of the basin where there is also a large PGV.
【作者单位】：中国地震局地球物理研究所;中国地质科学院地质力学研究所;
【基金】：国家重点研发计划课题(2017YFC0404901) 中央级公益性科研院所基本科研业务费专项(DQJB16A02) 地质调查项目(DD20160271) 国家自然科学基金项目(41572313)
【分类号】：P315.8

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