Analysis And Safety Appraisal Of Blasting Seismic Effects In Far Zone

The prediction and control of blasting casualty is always an important subject in engineering blasting field, especially the hazard of blasting seismic is focused more attention on. In this paper, according to the safety monitoring of excavation blasting in the project of Baiyanghe dam, Boshan area, Zibo city, on the basis of theoretical analysis and combined with vast field measured data, the transmission rules of blasting seismic, spectrum characteristics , blasting lasting time and their relations with blasting parameters are analysed and strength prediction accuracy is improved. Profound and systematic analysis are developed on the basis of others' researches.Due to the characteristics of blasting signal of short lasting time and nonstationarity, Fourier analysis and Wavelet packet analysis are creatively combined in analyzing blasting seismic spectrum, energy distribution in frequency field and time-frequency field. The multi-mater-frequency characteristic of blasting seismic energy and the transmission characteristic of blasting seismic wave are studied.In this paper, Blasting vibration can be looked upon as a motivate load for structures on the basis of theoretical of dynamics. The rules of response of single-degree-of-freedom system under different peak velocity, master frequency and lasting time are studied and applied in damage criterion. Through the comparing with nature seismic, the reasons of misrepresentation in appraising blasting earthquake by present blasting damage criterion are discussed, and methods are proposed to improve the irrationality. First the blasting seismic wave is subdivided into several bands by Wavelet packet transform, vibration amplitude and master frequency can be got on every band, so blasting vibration can be considered synthetically and the calculation accuracy are improved. Use the earthquake response equation of single degree of freedom as a carrier, the maximal amplitudes and master frequencies derived from every bands as inputs, the superposed response is computed. if the multi-master frequency response is compared with the value of safe state under present blasting seismic damage criterion, decisions can be made to conclude whether damages occur. The systematical and creative researches of the method of appraising blasting seismic damage is of great value to promote blasting seismic monitoring and casualty prediction into practice.