Study On Attenuation Law And Time-frequency Characteristics Of Embankment Vibration Under The Excitation Of Underwater Blasting

With the rapid development of infrastructure construction in China,underwater blasting is widely involved in a large number of underwater engineering construction.In order to evaluate the scientific nature and safety and reliability of blasting design scheme,it is often necessary to explore the attenuation mechanism and time-frequency characteristics of embankment vibration under underwater blasting excitation,so as to avoid damage to embankment and nearby buildings.Therefore,in-depth research on the attenuation law and time-frequency characteristics of embankment vibration under underwater blasting excitation is carried out.It is of great practical significance for engineering practice to design blasting implementation scheme based on test detonation data and to judge its safety and reliability.This paper focuses on the study of attenuation law and time-frequency characteristics of embankment vibration under the excitation of underwater blasting,and adopts theoretical analysis method,parameter fitting method,signal processing method and software method to comprehensively carry out the research work.The expression of embankment vibration intensity under the excitation of underwater blasting was deduced,and the noise reduction of vibration signals was analyzed by using different empirical mode decomposition and wavelet threshold method.The time-frequency characteristics of embankment vibration signals under the excitation of underwater blasting were explored.On this basis,the blasting vibration analysis software was developed.In order to explore the underwater blasting in embankment geotechnical vibration excitation and its attenuation rule,using dimensional analysis,considering the changes of water and soil medium,established the underwater blasting under the incentive function relation between the key parameters of impact bank vibration,combining with the vibration data fitting,nonlinear regression fitting algorithm and genetic algorithm to solve the blasting vibration intensity expression of their own,And compared with the predicted value of Sadowski formula.The results show that based on genetic algorithm fitting,the expression of blasting vibration intensity derived by dimensional analysis is more accurate in predicting the velocity of embankment vibration.The blasting vibration signals were de-noised by using different empirical mode decomposition and wavelet threshold method.On this basis,the IMF component and time spectrum of EMD,EEMD and ICEEMDAN were compared and analyzed.The results show that the signal to noise ratio(SNR)and root mean square error(RMS)are the largest and smallest after using the ICEEMDAN-wavelet threshold method,and the noise reduction effect is the best.The IMF component obtained by ICEEMDAN decomposition is the most stable among the three methods,which can inhibit the mode aliasing problem to some extent.Meanwhile,the resolution of the time spectrum of ICEEMDAN is higher than that obtained by EMD and EEMD decomposition and transformation in both time domain and frequency domain.Therefore,ICEEMDAN decomposition method can be used to analyze blasting vibration signals better.Combined with ICEEMDAN decomposition method and Hilbert transform,timefrequency analysis of embankment vibration signals under underwater blasting excitation is carried out.The results show that when exploring the energy distribution of each IMF component in the frequency band,the three components of IMF3～IMF5account for 90.77% of the total energy,accounting for most of the energy.At the same time,the energy occupied by each frequency band was further explored,and it was found that the energy carried by the 0-15 Hz frequency band accounted for 18.55% of the total energy.Since the natural frequency of the building was within this range,the blasting was prone to resonance and rupture.Therefore,attention should be paid to the low-frequency part.50～100Hz is the main frequency band of the vibration signal,and the energy of this frequency band accounts for 34.51% of the total energy.The energy occupied by the frequency band within the range of 200 Hz reaches 89.99%.Therefore,it can be considered that the vibration frequency of blasting vibration signal is within the range of 200 Hz.Based on MATLAB App Designer,an analysis software for the attenuation law of embankment vibration and time-frequency characteristics under the excitation of underwater blasting was designed and developed.After the interface design and application development of the software were completed,the software was packaged by creating a desktop application program,and its operation function was tested.The results show that the software can intuitively achieve parameters fitting,noise reduction and frequency analysis functions through visual output,which has a certain application value for related engineering problems.