考虑震源机制的设定地震滑坡危险性评价研究

The focal mechanism of an earthquake reflects the initial seismic dynamic conditions that induces landslides and has remarkable influence on the characteristics such as the spatial distribution and dominant direction of ground motion. Thus, it is necessary to considering the effect of focal mechanism in seismic landslide hazard assessment. Taking the slope belts in Tianshui city which is prone to strong earthquakes and large landslides as an example, scenario earthquake-induced landslide hazard assessments are carried out considering the strike-slip and reverse-oblique fault mechanisms based on the numerical simulation method and Newmark displacement model. The correlation relationship between the displacement and PGA and Arias Intensity is studied. The effect of the direction of ground motion on the displacement value is also analyzed. Through this research, it could reveal the mechanism of the influence of focal mechanism on the spatial distribution and the slip direction of the landslides. Moreover, a scenario earthquake-induced landslide hazard assessment method considering focal mechanism could be developed, which will improve the precision of seismic landslide risk assessment and the ability of disaster scenario simulation, and provide theoretical basis and technical support for the land use planning and seismic landslides disaster mitigation in the urban area.

地震震源机制决定了诱发斜坡失稳的初始地震动力条件，间接控制了区域滑坡的分布规律和优势滑动方向。因此，震源机制是地震滑坡危险性精细化定量评价必须考虑的因素。本申请拟选取强震活动频繁及大型滑坡多发的天水市区斜坡带，运用数值模拟和Newmark位移方法，开展走滑及走滑兼逆冲两种震源机制条件的设定地震滑坡危险性预测研究。具体通过分析两种震源机制条件下地震动强度参数与Newmark位移的量化关系，揭示震源机制对区域地震滑坡空间分布的控制作用；分析地震动加载方向与滑坡位移量的关系，揭示震源机制对区域滑坡优势滑动方向的影响机制；考虑地震动加载方向和坡向组合对地震滑坡位移的影响，改进Newmark位移预测模型，探索建立考虑震源机制的设定地震滑坡危险性预测理论与技术方法。研究成果有望提升地震滑坡危险性定量评估的精细化水平和灾害情景模拟能力，为山区城镇与重大工程的地震减灾和风险控制提供依据和支撑。

我国地震活动强烈，山区分布面积广泛，使得我国成为世界上地震滑坡灾害最为严重的国家之一。考虑震源机制的影响开展设定地震滑坡危险性评估，有助于提升地震滑坡危险性精细化定量评价水平，减轻地震滑坡灾害。本项研究通过分析不同震源机制条件下地震动强度参数空间分布的差异，揭示震源机制对区域地震滑坡空间分布的控制作用；重点分析逆冲型地震垂直断层、平行断层分量地震动空间分布差异，揭示震源机制对区域滑坡优势滑动方向的影响机制；使用国内强震数据，采用地震滑坡密切相关的阿里亚斯强度参数改进Newmark位移预测模型，初步构建了全国工程地质岩性分组与强度参数数据库，结合地形数据产出全国地震滑坡临界加速度分布数据成果，初步满足设定地震滑坡危险性评估需求，初步形成了考虑震源机制的设定地震滑坡危险性预测理论与技术方法。研究成果有望提升地震滑坡危险性定量评估的精细化水平和灾害情景模拟能力，为山区城镇与重大工程的地震减灾和风险控制提供依据和支撑。