基于KiK-net和K-NET台站记录研究熊本Mw7.0级地震近场地震动特征

发布时间：2018-06-07 02:20

本文选题：熊本地震 + 强地震动　；参考：《中国地震局地球物理研究所》2017年硕士论文

【摘要】：本文选取日本熊本MW7.0地震中断层距小于200km的255个强震台站记录到的三分量记录数据,研究了近场地震动特性的衰减和空间分布特征、竖向地震动特性,并分析了浅层场地放大效应、近断层方向性效应等因素对近断层地震动特性的影响。一、近场地震动衰减和空间分布特征研究。将近场地面运动水平向的峰值加速度、峰值速度及周期为0.2s、1.0s、2.0s、3.0s、5.0s和10.0s的加速度反应谱数据与美国NGA-West2的地震动预测模型相比较,研究熊本地震地表和井下地震动峰值及反应谱的衰减特征;选取位于破裂传播方向上与传播反方向记录数据,考察水平向加速度、速度时程以及反应谱的差异。研究结果表明:(1)对于井下观测结果,NGA-West2的地震动模型对PGA和短周期0.2s的反应谱的预测值与观测值相比整体偏高,而对PGV和较长周期地震动的预测值与观测值较为吻合。(2)对于地表观测结果,NGA-West2的地震动模型对PGA、PGV和短周期0.2s地震动反应谱的预测值与真实值较为吻合,而对较长周期地震动的预测值略高于观测值。(3)加速度时程记录及速度时程记录中均观测到明显的方向性效应;随着断层距的逐渐增大,方向性效应的影响逐渐减弱。(4)从反应谱来看,方向性效应对破裂传播方向上的近场地震动的放大作用明显,尤其是在长周期段。二、竖向与水平向地震动对比研究。将255个近场台站的地表和井下记录按断层距、场地类别进行分组,研究熊本地震近断层竖向/水平向地震动谱比特征,以及受断层距和场地条件的影响规律。研究结果表明:(1)井下地震动竖向/水平向(V/H)均值整体上高于2/3;0.4s-1s及3s-10s的周期内的反应谱V/H均值明显高于其他周期段;短周期(T0.1s)段剪切波速较低的D类场地的V/H均值整体上要比B类及C类高。(2)地表地震动V/H均值并未整体大于2/3,且大于1的情况较少;短周期(T0.1s)及3s-10s的周期内的反应谱V/H比值明显高于中间周期段;周期大于1s时,V/H均值呈现出明显的随周期增大的情况;剪切波速高的B类场地的V/H均值整体上要比剪切波速低的C类、D类、E类场地上的V/H均值高,且在短周期段表现得尤为明显;在短周期(0.1s)部分,断层距小于30km的近场台站记录到的V/H均值要显著高于断层距大于30km的台站,显示了竖向地震动的近场效应。(3)总体来看,井下与地表反应谱V/H均值随周期的变化大体相似,但井下的反应谱V/H均值明显高于地表,这从一个侧面说明井下地震动受到的浅层放大作用小,竖向与水平地震相差较小。三、浅层场地放大效应研究。通过比较KiK-net台站地表与井下记录结果,探讨浅层场地放大效应的影响。研究结果表明:(1)相对于井下记录,地表记录的地震动峰值PGA、PGV和周期为0.2s、1.0s和2.0s的反应谱有明显的放大,这种放大作用随浅层场地剪切波速的增大而减小;周期为3s、5s和10s长周期地震动的放大效应很小。(2)近场记录观测到了明显的场地非线性反应,相对于弱震动作用的情况,在PGA100 cm/s2的强震动作用时,放大作用曲线的卓越周期向长周期方向移动,地表/井下的放大倍数值显著减小。(3)地表/井下的反应谱比值随周期显著变化,场地放大作用影响在周期0.1~0.5s时最强;随着场地剪切波速VS30的减小,场地放大作用的影响向长周期方向移动,表现出明显的非线性特征。
[Abstract]:In this paper, the three component records recorded by 255 strong earthquake stations less than 200km in the MW7.0 earthquake of Xiongben, Japan, are selected to study the attenuation and spatial distribution characteristics of the near ground motion, the characteristics of the vertical ground motion, and the analysis of the effect of the shallow ground field and the near fault square direction on the characteristics of the near fault ground motion. Study on the dynamic attenuation and spatial distribution characteristics of near field earthquakes. The peak acceleration, peak velocity and period of the near field ground motion are 0.2S, 1.0s, 2.0S, 3.0s, 5.0s and 10.0s are compared with the earthquake prediction models of American NGA-West2, and the peak and response of ground and downhole ground motion in Xiongben earthquake are studied. The results show that: (1) for the underground observation results, the prediction value of the response spectrum of the NGA-West2 ground motion model to the PGA and the short period 0.2S is higher than the overall observation value. The predicted values of PGV and long period ground motions are in good agreement with the observed values. (2) for the ground surface observation results, the prediction values of the NGA-West2 ground motion models for PGA, PGV and short period 0.2S ground motion are in good agreement with the true values, while the predicted values for long period ground motions are slightly higher than those of the observed values. (3) the time history and velocity of acceleration. The obvious directional effect was observed in the course records; with the gradual increase of the fault distance, the influence of the directional effect gradually weakened. (4) from the response spectrum, the directional effect magnified the near ground motion in the direction of rupture propagation, especially in the long period. Two, the vertical and horizontal seismic contrastive studies. 255 close. The surface and downhole records of the station are grouped according to fault distance and site category to study the characteristics of the vertical / horizontal seismic dynamic spectrum ratio of the near fault in Xiongben earthquake, as well as the influence of the fault distance and site conditions. The results show that (1) the vertical / horizontal direction (V/ H) mean of underground ground motion is higher than that of 2/3, 0.4s-1s and 3s-10s. The V/H mean of the response spectrum is obviously higher than that of other periods, and the V/H mean of the D class with the lower shear wave velocity of the short period (T0.1s) section is higher than that of the B class and the C class. (2) the surface seismic dynamic V/H mean is not larger than the 2/3, and the case is less than 1; the ratio of the reaction spectrum V/H to the short period (T0.1s) and 3s-10s is obviously higher than that in the middle period. When the period is greater than 1s, the mean V/H mean is obviously increased with the period, and the V/H mean of the B class with high shear wave speed is higher than that of the C, D, E, which is higher than the shear wave velocity, especially in the short period, and in the short period (0.1s) part, the V/H of the fault distance is smaller than the 30km near field station. The value should be significantly higher than the station of the fault distance greater than 30km, showing the near field effect of the vertical ground motion. (3) in general, the V/H mean of the downhole and surface response spectrum is roughly similar to the change of the period, but the V/H mean of the downhole response spectrum is obviously higher than the surface, which indicates that the shallow layer enlargement of the ground motion under the well is small, the vertical and the water are shown in one side. The difference between the flat earthquakes is smaller. Three, the study on the amplification effect of the shallow site. By comparing the surface and downhole records of the KiK-net stations, the influence of the amplification effect on the shallow ground is discussed. The results show that (1) the peak vibration peak PGA, PGV and period recorded on the ground surface, compared with the downhole record, are obviously magnified in the response spectrum of 1.0s and 2.0S. The large effect decreases with the increase of the shear wave velocity of the shallow site; the period is 3S, the amplification effect of the long periodic ground motion of 5S and 10s is very small. (2) the near field record observed the obvious nonlinear response of the site. Compared with the weak vibration, the remarkable period of the amplification curve moves to the long period direction when the strong motion of PGA100 cm/s2 is strong. (3) the ratio of the surface / downhole response spectrum is significantly changed with the cycle, and the effect of site amplification on the cycle 0.1~0.5s is the strongest. With the decrease of the field shear wave velocity VS30, the effect of the site enlargement moves to the long period direction, showing obvious nonlinear characteristics.
【学位授予单位】：中国地震局地球物理研究所
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315

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