Signal Analysis Of Collapsing Vibration And The Research And Application Of Ground Motion Power Spectrum

With the continuous acceleration of the urban process,the old city reconstruction,demolition,expansion and other engineering projects are becoming more and more large,it makes demolition blasting technology with the advantages of safety,efficiency,economy and environmental protection become the first choice in demolition industry.However,with the demolition blasting of the construction building is gradually moving towards the direction of more and more larger scale and higher height,it also puts forward a more severe challenge to the blasting demolition technology.In practical engineering,too much reliance is placed on empirical regression formulas in the study of the propagation process and attenuation law of collapsing touchdown seismic waves.It is neglected to understand blasting vibration from the point of view of physical phenomena and processes.Therefore,from the view of physical phenomena,it can not only reflect the seismic characteristics of demolition blasting and the dynamic response of buildings,but also accord with the mechanism of buildings being damaged by earthquakes.And the simple dynamic response analysis method and safety evaluation standard will have important theoretical significance and engineering application value.In this paper,after analyzing the research status of collapsing vibration effect of demolition blasting,relies on the project of a large demolition blasting building group project and based on the modern signal processing method in the field of engineering.The local and detailed characteristics of demolition blasting vibration signal are studied and analyzed.From the physical level,random fourier spectrum considering the focal mechanism,propagation path and local site conditions is proposed.Furthermore,the function of acceleration power spectrum model for ground motion of collapse vibration is established.The dynamic response of the surrounding building structure is analyzed in frequency domain based on power spectrum model of collapse vibration,the specific research contents are as follows:(1)The characteristics of collapsing vibration caused by demolition of blasting buildings are summarized systematically.Based on the signal processing methods such as wavelet analysis and HHT analysis,the energy distribution in different frequency bands of field measured data and the attenuation characteristics with source distance are analyzed on the basis of a large demolition blasting building complex project.Find: compared with wavelet analysis,wavelet packet analysis can show in detail the energy distribution characteristics of the vibration signal in different frequency bands,and has better recognition ability.The analysis of collapse vibration signal by using Hilbert three-dimensional energy spectrum can more synthetically express the safety evaluation of amplitude,frequency and duration to the collapse vibration effect.(2)According to the seismological principle,based on the characteristics of collapsing vibration of demolition blasting.More careful consideration is given to the source,propagation and attenuation characteristics of collapsing touchdown seismic waves,the source spectrum,propagation path transfer function and local site conditional transfer function are established in frequency domain.Based on the Wiener Sinchin theorem and the transformation between the frequency response function and the pulse function,transform it into the power spectrum model of ground motion of collapse vibration.Furthermore,the power spectrum model of ground motion of collapse vibration is obtained,which includes the total mass of demolition blasting building,the acceleration of gravity,the height of centroid,the source moment,the propagation path and the site conditions,etc.And the feasibility of the power spectrum model is verified by practical engineering cases.(3)Based on the established power spectrum model of ground motion of collapsing vibration,the dynamic response analysis program of the simplified model of Single particle model of structure under the action of power spectrum of collapsing vibration by using MATLAB Software.Furthermore,the dynamic response of the building structure with different natural period at the same source distance under the action of collapsing vibration of demolition blasting is analyzed.Result display: Based on the ground motion power spectrum model of collapse vibration,the displacement response spectrum,velocity response spectrum and acceleration response spectrum of the structure under random vibration excitation can be obtained more quickly.The structural dynamic response spectrum can express the damage of the building structure intuitively and provide a powerful basis for the prediction of collapse vibration effect.(4)At the same focal distance,comparison of response displacement angle,the maximum velocity response and the maximum acceleration response of building structures with different natural periods under the action of collapse vibration.However,the dynamic response of different building structures is very different,which shows that the inherent properties of the structure are also the important factors that affect the dynamic response of the building structure under the effect of collapse vibration.