Study On Multi-parameter Of Earthquake Alarm Of Rail Transit

Because of acceleration of urbanization in China,the urban population increases constantly and the number of various vehicles also increases.Therefore,urban traffic pressure has increased dramatically.After entering the 21^st Century,Chinese government vigorously develops urban rail transit to relieve the traffic pressure.As one of the countries where the earthquakes are most likely to occur in,it is urgent for China to carry out the research on earthquake emergency disposal technology of urban rail transit so as to prevent or reduce the damage of earthquake disaster to rail traffic and ensure the safety of passengers'life and property.In view of the present situation that only the peak acceleration PGA is used as a single-parameter alarm in earthquake alarm,this paper studies the multi-parameter earthquake alarm method for urban rail transit.Based on the ambient vibration data,this paper analyzes the microtremor and vehicle passing vibration signals in detail,and gives the frequency band range of filtering environmental vibration and noise.This paper makes analogies to the traditional method,and proposes a automatic search algorithm for low frequent cut-off frequency to determine the low frequent cut-off frequency of massive seismic data.With the seismic data after the filtering of vehicle passing vibration signal,this paper carries out researches on the various earthquake alarm parameters for urban rail transit.The main content of the paper are as follows:1.Analyzed the microtremor and vehicle passing vibration signal of Harbin metro.According to the corresponding relationship between the dominant period of the microtremor signal and the site type,this paper determined the high frequent cut-off frequency of the seismic data band-pass filter is 10Hz.And according to the main frequency components of vehicle passing vibration signal and massive earthquake records,this paper determined the low frequent cut-off frequency of the seismic data band-pass filter is 0.3Hz.2.According to the low efficiency of traditional method when determining filtered low frequent cut-off frequency in the strong earthquakes recording processing,this paper put forward a automatic search model for filtered low frequent cut-off frequency,and used the loss function of statistical learning method to determine the end condition of the automatic search model process.Based on two earthquakes,Wenchuan and Lushan,and the seismic data--K-NET of Japan,this paper compared the result of the automatic search algorithm with the low frequent cut-off frequency which determined by the traditional method.The result showed that the differences of CAV,Is and Sa between two times calculations,one time used the low frequent cut-off frequency which determined by the automatic search algorithm and the other time used the fixed 0.3Hz as the filtered low frequent cut-off frequency,are small.This indicated that fixed 0.3Hz as the low frequent cut-off frequency is reasonable.The calculation efficiency of the algorithm is much better than that of the traditional method.It is especially suitable for massive recording of strong earthquakes.3.Considering the site conditions of the urban rail transit platform,this paper divided Japan's K-NET seismic data into two classes--class II and class III.Then it analyzed the statistical law between the peak acceleration PGA and CAV,IV2,Ia and Sa to give the method to determine the earthquake alarm threshold.According to the statistical law,the alarm threshold of CAV,IV2,Ia and Sa is determined by the PGA earthquake alarm threshold.Comparing all kinds of seismic alarm modes with single-parameter and double-parameter combinations,the analysis of the results of the alarm shows that the similarity of different results of various seismic alarm methods is high.However,there are too much alarm which does not affect the operation security in the single-parameter PGA alarm mode.So It provides a technical reference for double parameters as a joint alarm mode.