李郑梁,李建春,刘波,等. 2021.浅切割的高山峡谷复杂地形的地震动放大效应研究[J].工程地质学报,29(1):137-150. doi:10.13544/j.cnki.jeg.2021-0002. DOI: 10.13544/j.cnki.jeg.2021-0002
    引用本文: 李郑梁,李建春,刘波,等. 2021.浅切割的高山峡谷复杂地形的地震动放大效应研究[J].工程地质学报,29(1):137-150. doi:10.13544/j.cnki.jeg.2021-0002. DOI: 10.13544/j.cnki.jeg.2021-0002
    Li Zhengliang, Li Jianchun, Liu Bo, et al. 2021. Seismic motion amplification effect of shallow-cutting hill-canyon composite topography[J]. Journal of Engineering Geology, 29(1): 137-150. doi: 10.13544/j.cnki.jeg.2021-0002.
    Citation: Li Zhengliang, Li Jianchun, Liu Bo, et al. 2021. Seismic motion amplification effect of shallow-cutting hill-canyon composite topography[J]. Journal of Engineering Geology, 29(1): 137-150. doi: 10.13544/j.cnki.jeg.2021-0002.

    浅切割的高山峡谷复杂地形的地震动放大效应研究

    SEISMIC MOTION AMPLIFICATION EFFECT OF SHALLOW-CUTTING HILL-CANYON COMPOSITE TOPOGRAPHY

    • 摘要: 高山峡谷复杂地形是我国西部地区常见的地形和场地条件,大量的工程(桥梁、大坝等)修建在这类场地上。实际震害调查结果表明不规则地形对地震动具有明显的放大作用,对边坡的稳定性和建筑物的安全性构成不利的影响。因此研究高山峡谷复杂地形的地震动放大效应具有重要的工程价值。本文针对浅切割的高山峡谷复杂地形(山体顶和峡谷底的高差在100~500 m范围内),基于边界积分方程法获得场地任意点的地震动,详细探讨了入射波类型(P波和SV波)、入射波频率、入射角、山体和峡谷的几何参数对浅切割的高山峡谷复杂地形的地震动放大效应的影响,发现山体的存在明显改变场地地震动的空间分布;高山峡谷复杂地形对地表地震动的放大作用与入射波频率密切相关;不同的地震波类型对应不同的地震动空间分布模式;峡谷深度对地震动放大效应的影响取决于入射波的类型;不对称的几何形状导致地震动的空间分布也呈现明显的不对称,并且SV波入射时的不对称性强于P波;当地震波斜入射时,峡谷背向震源侧的地震动远大于面向震源侧的地震动。本文的研究方法可以获得考虑高山峡谷复杂地形地震动放大效应的场地任意位置的地震动,为边坡的稳定性分析提供更符合实际的地震输入。

       

      Abstract: The hill-canyon composite topography is a common site in Western China. A large number of infrastructures, such as bridges and dams, have been built in such a site. However, field investigations after earthquakes show that surface irregularities may cause seismic motions amplified in such a site. Seismic motion amplification has an adverse effect on the stability of slopes and the safety of buildings. Therefore, it is significant to investigate the seismic motion amplification effect of hill-canyon composite topography. In this paper, we focused on the seismic response of the shallow-cutting hill-canyon composite topography. In such a site, the relative height between the hill top and the base of canyon always ranges from 100 m to 500 m. Employing the boundary integral equation method, the seismic motion at every interesting position in such a site was obtained. Then, parametric studies were conducted, including the effects of the types of waves(P and SV waves), the frequencies of incident waves, the angles of incidence, and the geometry characteristics of the hills and canyons on the seismic motion amplification effect of hill-canyon composite topography. The results show that the existence of the hills clearly changes the spatial distribution of seismic motions. The surface seismic motion is either amplified or de-amplified, depending on the frequency of incident wave. Different types of waves determine different spatial distribution patterns of seismic motions. The influence of the depth of the canyon on amplification pattern depends on the types of waves. The geometric asymmetry contributes to the asymmetry of the spatial distribution of seismic motions. The asymmetry is much clearer in the case of SV wave incidence than that in the case of P wave incidence. In the case of oblique incidence, seismic motions near the slope facing away from the source are much larger than those near the slope facing towards the source in the canyon. The method in this paper is efficient to investigate the seismic motion amplification effect of hill-canyon composite topography, and capable to obtain the seismic motion at every position, which will be used in the stability analysis of slopes.

       

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