Abstract:

The relationship between the time and frequency of blasting vibration monitoring signal monitored from the construction of a shallow tunnel in Qingdao crossing underneath buildings is studied by means of HHT analysis theory and MATLAB programming software, and the interval between the ignitions of the detonators is analyzed, so as to provide theoretical reference for vibration control. Conclusions drawn are as follows: 1) The frequency of the blasting vibration signals is basically below 90 Hz, and the dominant frequency range is from 20 Hz to 70 Hz; 2) The allowable safe vibration velocity of No. 3 building can be designed at 2.0 cm/s according to the blasting safety regulations. The designed safe vibration velocity value, i.e., 1.0 cm/s, is relatively conservative; 3) 60 ms will be the ideal time interval between detonators, without considering the delay errors of the detonators; 4) Delay errors of detonators generally exist in blasting, and generally the error is a positive value. 

Key words: HHT, blasting, vibration control, shallow tunnel, frequency, delay time