轨道交通地震预警系统的基础研究

Earthquake Early Warning has been an important measure to mitigation of seismic hazards for rail traffic systems in a number of countries, such as in Japan and Mexico. Some of railway and urban rail traffic systems in China are located within high intensity earthquake area. The running safety of rail traffic systems during earthquake is one of the significant problems of earthquake disaster prevention and reduction. However, the research and application of early warning system in China is still limited up to date. The project focus on the fundamental research of Earthquake Early Warning System based on P-wave for rail transit systems, considering the structure characteristic of systems in China. The running safety of rail traffic train during earthquake, the earthquake early warning strategies, the warning earthquake threshold, the relationship between the final seismic intensity and P-wave parameters for various seismic source mechanisms and travel paths, and the earthquake intensity prediction model applicable to regional and in site early warning system will be systematically investigated. The objective of the research is to build a more accurate prediction model for track traffic system; to establish the earthquake early warning criteria and early warning strategy, and to design an earthquake early warning system prototype combined regional early warning and in site early warning for rail traffic system. The results of the research can give a theoretical fundamental for the development and application of earthquake early warning system for rail transit system and has a direct and good application prospect. They will also have an important reference value for early warning and earthquake disaster mitigation of other kind of important engineering.

地震预警已成为日本等国减轻轨道交通地震灾害和次生灾害的重要手段。我国部分铁路和城市轨道交通处于高烈度地震设防区，地震过程中运行中的轨道交通列车运行安全抗震减灾的重要问题之一，但在重大工程的预警系统的基础研究和应用方面比较落后。本项目拟对地震作用下轨道交通列车运行安全、轨道交通地震预警机制和预警地震动阈值、不同震源机制的各种早期地震动P波特征参数与最终地震动强度的关系、适用于区域预警和原位预警的早期P波地震动特征参数以及最终地震动强度预测模型等问题进行系统研究。考虑震源-传播路径-场地效应，建立先达P波特征参数与地震动强度之间的更准确的预测模型；提出轨道交通的地震预警策略和预警标准，设计一个区域预警与原位预警相结合的轨道交通预警系统原型。本课题的成果可以为轨道交通地震预警系统的开发和建设提供理论基础，有直接和良好的应用前景，对其他重大工程的地震预警和抗震减灾也有重要参考价值。

对轨道交通预警系统的基础理论进行了研究，提出了单台站原位P波预警的基本构想。研究了强震P波参数与强震震级的回归关系，提出了强震P波瞬时特征周期和平均特征周期参数快速估算震级的回归算法，得到了不同时间窗的回归公式。对强震的早期P波特征周期参数和幅值参数与地震地面震动峰值参数之间的关系进行了研究，提出了P波特征周期与地震地面峰值加速度、峰值幅度的回归关系，P波幅值参数与地面震动峰值加速度、峰值速度之间的回归关系。研究了局部场地特征和入射方向对强震P波特征参数的影响。研究了基于Bayes原理的渐进地面震动强度预警与P波特征参数，提出了地面震动强度参数的初始先验分布假定和实时估算渐进地面震动强度参数的方法，验证了其可行性。在区分震源机制与不区分震源机制两种情况下提出了P波的特征周期参数与地震地面峰值加速度参数的线性回归关系式，证明正断层机制下的两种幅值参数与地震动强度参数的线性相关度较不区分震源机制的情况下均有明显的增强。研究了P波特征参数的概率统计特征，给出了基于不同地震动强度范围内不同时窗下的P波特征参数的统计分布特征以及概率分布函数。研究了地震作用下列车轨道动力相互作用，提出了一个将地震作用对运行中列车安全影响分解为列车在常规条件下的运行安全指标叠加地震作用对列车运行安全指标的简化研究思路，建立了车轮-轨道-路基数值模拟分析模型，并通过数值模拟分析了路基条件、地震动特性等对列车运行安全指标的影响，并将计算结果与日本文献结果进行的对比验证，表明轮轨之间采用硬接触和赫兹接触均可得到较满意的模拟结果。基于我国高速铁路地震预警采用沿线路排列的原位地震监测网络所必需的单台站预警模式，提出了适合高速铁路单台站的快速、准确进行高铁线路场地地震动预测的方法。