The Analyses On Microtremor Frequency Spectrum Structural In The Urban Area Of Taiyuan

Earthquake is a sort of galactic devastating natural disaster, at present, the level about earthquake prediction that it do not pass a barrier remain exploratory research phase. China is the most serious earthquake disaster country in the world, several provinces and cities suffer more than 6 level earthquake disaster raid in the history. Shanxi province belongs to North China earthquake zone, earthquake remain the extraordinary activity period since Quaternary period. Taiyuan locates on the north of Fen-Wei earthquake belt, it is one of fifty-four city which are the stress earthquake protection in whole country.It indicates that site effect is the important cause which conduce build collapse, engineering establishment destroy and induce a series of subordinate disaster in the every disaster survey after the earthquake. The vibration effect could arise construction sympathy render to structural damage. The incidence probability and destroy scale of the vibration effect depend upon the natural vibration period of foundation. The natural vibration period of the foundation vibration performance by the microtremor test because it reflect the dynamics of the site soil. The measuring method of the parameter have been approved for much of the theory and the practice.The test technique of microtremor was firstly found and researched in Japan, and introduce to China at the 1950s in the 20th-century, now, it has became into the mature mearsurement technology, At present the means which obtain site predominant period are mainly wave velocity logging and the microtrmor test, however microtremor test is used by more and more in the engineering filed owing to its merit which include the convenience and the immediacy and the economy.The paper analyse eigenperiod value of microtremor, which adopts the means of mathematical statistics with the test record of the microtretor and wave velocity logging at the high-rise site for research foundation in Taiyuan. The totality feature ahout the microtremor is that the eigenperiod value(low frequency) is higher, predominant period value is close at the each of the direction(E-W,N-S,V-T),with the frequency spectrum feature of the concentrated value distribution about predominant period.The feature about the frequency spectrum of microtremor totality show that multimodal and low frequency through the analyses about the microtremor spectrogram tested in this article. It is related with the construct of the test site and total stratum construct about Taiyuan, especially it has consanguineous relation with the dynamics characteristic of stratum.Finally, on base of beam measure well data on every field, author get connection formula between microtremor character cycle with equivalent wave speed through regressive analyse, intend microtremor excellence cycle value of several fields which are not done microtremor test, and obtain isoline figure of microtremor excellence cycle value in entire city.Study result of the paper is benefit for in-depth understanding microtremor characteristic,it play a impel role on microtremor application in engineering practice,at the same time,it supplies referenced worthiness for aseismatic design, quakeproof and city earthquake district build in Taiyuan city.