Abstract:Vibration from blasting for construction of a water conveyance tunnel at the Baifeng Reservoir main dam has potential effects on dam safety.In order to ensure the safety of the dam during blasting for the main dam water conveyance tunnel,blasting vibration must be monitored.By analyzing particle vibrating velocity,the effects of blasting vibration on the dam were monitored.Vibrations during four blasting events were monitored.Correlative data was collected using a TC-4850 vibrometer and a 3-component TYTEST velocity sensor.The response and characteristics of vibration from construction blasting were analyzed based on the data from three directions at each measuring point.Measurements included vibration history,peak,and frequency spectrum analysis.Results of the peak analysis showed that the maximum vibration velocity at each measuring point was less than 1.0 cm/s.This satisfied the design requirements for the control of blasting vibration velocity.The maximum vertical and horizontal displacements at each measuring point were within 0.013 mm.The maximum vertical and horizontal accelerations at each measuring point were within 2.559 m/s2.Results of the frequency spectrum analysis showed that the vertical and horizontal vibration frequency corresponding to maximum peaks on the Fourier spectrum were in the range of 14.71~34.0 Hz.This range of frequency response was outside the natural response frequency of dam structure,which did not experience the effects of resonance.Compared with the particle vibration velocity of the dam's foundation,the particle vibration velocity at the top of the dam structure was amplified.Therefore,the particle vibration velocity at the dam foundation was less than that at the top of the dam,and consequently,under the threshold at which security controls at the dam's foundation would be triggered.All of the analyses demonstrated that blasting vibration associated with construction of the conveyance tunnel had no significant effects on dam safety and stability.
