Abstract: The underwater explosion vessel was used to simulate the water depth of 40 m,and two sets of underwater concrete models with different charge structures were used to conduct a single blasting damage test with the same charge amount.Before and after blasting,the active signals of the concrete samples along the central axis of the hole were collected by using the active monitoring method of piezoelectric ceramic sensors.Through the statistical analysis of the peak value and energy of the signal at the monitoring point,it is found that the signal received along the direction of the hole gradually increases,and the peak value and energy of the signal received near the bottom of the hole appear obvious mutation.By comparing the position of the mutation point under different charge structures,it is found that the mutation point of the sample with high impedance ball and coarse sand at the bottom of the hole is significantly advanced,indicating that the damage depth of the retained concrete part at the bottom of the hole is small.Finally,the frequency law of piezoelectric signal before and after blasting was studied by EMD method.The research showed that the underwater energy dissipation blasting technology can effectively weaken the damage to bedrock rock mass caused by borehole blasting,and the damage monitoring method based on piezoelectric signal can be used to monitor the damage depth of rock mass in underwater borehole blasting.

Key words: underwater blasting,model test,explosive container,piezoelectric ceramics,damage monitoring