申通, 王运生, 罗永红, 赵波, 辛聪聪, 贺建先, 古德章, 张得彦. 2018: 九寨沟MS7.0级地震斜坡地震动响应监测研究. 工程地质学报, 26(6): 1611-1621. DOI: 10.13544/j.cnki.jeg.2017-446
    引用本文: 申通, 王运生, 罗永红, 赵波, 辛聪聪, 贺建先, 古德章, 张得彦. 2018: 九寨沟MS7.0级地震斜坡地震动响应监测研究. 工程地质学报, 26(6): 1611-1621. DOI: 10.13544/j.cnki.jeg.2017-446
    SHEN Tong, WANG Yunsheng, LUO Yonghong, ZHAO Bo, XIN Congcong, HE Jianxian, GU Dezhang, ZHANG Deyan. 2018: MONITORING RESULT AND ANALYSIS OF SLOPE SEISMIC RESPONSE DURING THE JIUZHAIGOU MS7.0 EARTHQUAKE. JOURNAL OF ENGINEERING GEOLOGY, 26(6): 1611-1621. DOI: 10.13544/j.cnki.jeg.2017-446
    Citation: SHEN Tong, WANG Yunsheng, LUO Yonghong, ZHAO Bo, XIN Congcong, HE Jianxian, GU Dezhang, ZHANG Deyan. 2018: MONITORING RESULT AND ANALYSIS OF SLOPE SEISMIC RESPONSE DURING THE JIUZHAIGOU MS7.0 EARTHQUAKE. JOURNAL OF ENGINEERING GEOLOGY, 26(6): 1611-1621. DOI: 10.13544/j.cnki.jeg.2017-446

    九寨沟MS7.0级地震斜坡地震动响应监测研究

    MONITORING RESULT AND ANALYSIS OF SLOPE SEISMIC RESPONSE DURING THE JIUZHAIGOU MS7.0 EARTHQUAKE

    • 摘要: 通过在九寨沟县聚宝山不同位置处布设微震监测仪器,采集到了九寨沟MS7.0级地震后几次典型的余震监测数据。对地震动监测剖面上1#(1414 m)和2#(1551 m)监测点的余震加速度响应数据进行系统的研究,表明:(1)孤立突出山体的地形放大效应显著,各监测点的水平向加速度幅值一般要大于竖直向;(2)在地震过程中,聚宝山近SN走向的山脊沿水平东西方向震动更为猛烈,即沿东西两侧发生猛烈"甩动",形成沿山脊走向发育的地震裂缝。对余震监测数据的研究证实了斜坡地震动方向效应的存在,聚宝山山顶处的2#监测点水平东西向峰值加速度放大效应明显强于其他方向,地震波能量在水平东西向上得到显著放大,因而坡顶处建筑物也更容易沿该方向发生破坏,证明了局部地形对斜坡地震动力响应具有控制效应;(3)2#监测点竖直向主频值主要为6~12 Hz,水平东西向主频值主要为5~8 Hz,水平南北向主频值主要为5~10 Hz,其水平东西向主频率值主要为低频成分;相较于1#监测点,2#监测点各向的主频值发生明显衰减,即随着高程的增加,地震动主频值呈现出减小趋势,在斜坡上部地震波以中低频为主。通过进一步地计算分析得出,九寨沟地震诱发单薄山脊、条形山体、多面临空山体等地形放大效应与地震波半波长密切相关,斜坡在局部地形尺寸与地震波丰富的波长成分的耦合作用下,地形放大效应显著,山体震害发育。

       

      Abstract: The research group, just in the next day after the "8·8" Jiuzhaigou earthquake, installed microseismic monitoring instruments at the bottom(1# monitoring point) and the top(2# monitoring point) of the Jubao Mountain in the Jiuzhaigou county. They collected a good amount of seismic data during aftershocks. The paper seeks to research the seismic response characteristics through analysis of the monitoring data of 1# monitoring point at the elevation of 1414 m and 2# monitoring point at the elevatoion of 1551 m above mean sea level. The earthquake monitoring data show the follow features. (1)Compared with the low elevation monitoring point, the peak acceleration of the ground motion in all directions of the high elevation monitoring point show an increasing trend. The horizontal acceleration amplitude of each monitoring point is generally larger than the vertical direction. And the topographic amplification effect is remarkable. (2)During the aftershocks, near SN trending ridge of the Jubao Mountain quaked more fiercely along the east-west direction, which swung violently along the East and West sides of ridge, formed seismic fractures that developed along the ridge. The study of the aftershock monitoring data confirms the existence of the directional effect of the slope ground motion. The peak acceleration amplification effect of 2# monitoring station in horizontal East-West direction is obviously stronger than that in other directions. Seismic wave energy significantly magnified at the horizontal east-west direction. So, the top buildings were more easily damaged along this direction. These results proved that the local terrain had a controlling effect on slope seismic response. (3)The vertical main frequency of the amplitude spectrum of 2# monitoring point focused on the range between 6 Hz and 12 Hz. The horizontal East-West frequency focused on the lower frequency range between 5 Hz and 8 Hz. And the main frequency of horizontal north-south direction was mainly 5~10 Hz. Compared with the 1# monitoring point, the main frequency in all directions of the 2# monitoring point had obvious attenuation. That is, with the increase of the elevation, the main frequency of the seismic vibration showed a decreasing trend. And the seismic wave in the upper part of the slope was dominated by medium and low frequency. Further calculation and analysis showed that the topographic amplification effect of the thin ridge, the strip-type mountain and multiple free surfaces mountain were closely related to the half wave length of the seismic wave. Under the coupling effect of local topographic dimensions and the rich wavelength components of seismic waves, the topographic amplification effect was remarkable, and the seismic damage of the mountain was developed.

       

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