竖向地震效应下近断层边坡永久位移预测模型

利用改进的能量法从美国NGA数据库的4 669条地震记录中量化识别出305条近断层速度脉冲地震动。脉冲具有方向性效应,所有地震动均转换到最强脉冲方向。基于Newmark刚塑性理论模型,考虑竖向地震效应,输入拟合后的地震动,计算了边坡永久位移值。根据大量计算结果统计发现,竖向地震效应对近断层内的边坡永久位移有显著影响,既有边坡地震位移预测模型的预测值离散性较大。通过相关性分析,发现竖向效应作用下,边坡永久位移值与近断层地震动的峰值速度相关性显著。采用统计学回归分析方法,建立了基于峰值速度(PGV)、Arias强度(I_a)、临界加速度(a_c)的预测模型,该模型简单实用,可应用于近断层区域的边坡滑坡地质灾害风险评估。

Permanent Displacement Predictive Model of Near-fault Seismic Slope Consideration of Vertical Seismic Motion Influence

305 velocity pulse-like ground motions from 4 669 recordings in the next generation attenuation database(NGA) were identified using the latest improved energy-based approach. As conservative research, all ground motions were rotated and synthesized to the orientation of the strongest observed pulse for considering the directivity of the pulse effect. Newmark method was used to calculate the permanent displacement of slopes induced by near-fault ground motions with consideration of the effects of vertical acceleration time-histories. The analyses indicated that a non-ignorable had a great influence of the vertical acceleration time-histories on the permanent displacement of sliding system in the near-fault area. And the prediction result of existing predictive models for seismic displacement of slopes was big to the divergence. In addition, permanent displacement had a close relationship with the peak ground velocity using correlation analysis. Based on statistical methods, the regression model, is a function of peak ground velocity(PGV), Arias intensity(I_a)and critical acceleration(a_c), was generated to be used in probabilistic seismic hazard analysis in the near-fault area.