基于概率模型的高速铁路地震预警实时性与准确性分析

摘要

采用地震预警时延评价高速铁路地震预警的实时性,根据地震预警时延的特征,建立地震预警时延的偏置伽马分布模型,并给出偏置伽马分布的性质及其参数的极大似然估计算法.采用震源定位偏差评价地震预警的准确性,以震中距偏差服从伽马分布和方位角偏差服从均匀分布的二维随机变量,建立震源定位偏差的二维分布模型.以300条地震记录数据作为输入,对某高速铁路地震预警系统进行现场试验,验证所建立模型的正确性,并对高速铁路地震预警的实时性和准确性进行评价.结果表明:偏置伽马分布模型能够精确描述地震预警时延,伽马分布可有效描述震中距偏差;随着地震监测台站数量的增加,地震预警的实时性下降但准确性明显提高;地震监测台站数量取3和在70％概率情况下,地震预警可实现全系统时延小于7 s、震中距偏差小于20 km,能够满足高速铁路地震预警对实时性和准确性的要求.%Earthquake early warning time delay was used to evaluate the real time of earthquake early warning for high speed railway.According to the characteristics of earthquake early warning time delay,an offset gamma distribution model of earthquake early warning time delay was established.The nature of offset gamma distribution and a maximum likelihood estimation algorithm of distribution parameters were given.The seismic source location deviation was adopted to evaluate the accuracy of earthquake early warning.With the epicenter distance deviation obeying gamma distribution and the azimuth deviation obeying uniform distribution as two-dimensional random variables,a two-dimensional distribution model of source location deviation was established.Field tests of a high speed railway earthquake early warning system were carried out with 300 seismic record data as inputs to validate the correctness of the established models and evaluate the real time and accuracy of high speed railway earthquake early warning.Results show that the offset gamma distribution model can accurately describe the earthquake early warning time delay and the gamma distribution can effectively describe the epicenter distance deviation.With the increase of the number of seismic monitoring stations,the real time of earthquake early warning is decreased but the accuracy is obviously improved.With three earthquake monitoring stations and under 70％ probability,earthquake early warning can realize the time delay of the whole system less than 7 s and the epicenter distance deviation less than 20 km,which can satisfy the requirements for the real-time and accuracy of earthquake early warning for high speed railway.