Abstract
In order to study the energy characteristics of seismic waves on the liquid CO2 blasting system, the blasting seismic wave signal of liquid CO2 blasting was obtained by on-site microseismic monitoring tests. The adaptive optimal kernel time-frequency analysis method was used to study the basic time-frequency properties of the seismic wave signal. Combining wavelet packet transform decomposition and reconstruction and adaptive optimal kernel time-frequency analysis method, the liquid CO2 energy distribution of the seismic wave signal was further analyzed. And the energy regression model of seismic wave source of liquid CO2 blasting system was discussed. The results show that the vibration velocity is at a low level, and the main frequency range is between 30 and 70 Hz, and the duration is about 20-30 ms. The energy is mainly distributed in 0-125 Hz, which is composed of two main regions. The power function model can be used to describe the attenuation law of the seismic wave energy. The energy conversion coefficient and characteristic coefficient of the source of liquid CO2 blasting system were defined and analyzed. Combined with the empirical formula of the Sadovsky vibration velocity, the energy regression model of the seismic wave source of liquid CO2 blasting system was obtained.
Highlights
The cyclic nature of the drill-and-blast method, increasing excavation demands, environmental concerns, and trends towards safety, necessitates the development and exploration of the potential of new and improved concepts of rock excavation
The seismic wave signal of the No 1 test is shown. It can be seen from the diagram that the direct wave energy of liquid CO2 blasting signal is strong, and the attenuation speed is fast
In order to study the time-frequency and energy characteristics of seismic waves in the liquid CO2 blasting system, the liquid CO2 blasting seismic wave signal is obtained by field microseismic monitoring test
Summary
The cyclic nature of the drill-and-blast method, increasing excavation demands, environmental concerns, and trends towards safety, necessitates the development and exploration of the potential of new and improved concepts of rock excavation. One of the promising and nonexplosive concepts that warrants in-depth evaluation as a tool for rock fragmentation is the “Penetrating Cone Fracture” (PCF) method [1]. Liquid CO2 blasting system is one of the nonexplosive blasting technologies, which is based on liquid carbon dioxide being converted to high-pressure carbon dioxide gas or fluid with the ignition. The gas spreads through fissures and microcracks in the rock and breaks it in tension, rather than compression as with explosives, and the damage at lower tensile stress levels is more efficient in the utilization of energy, less vibration, pollution-free, reduce the damage of the surrounding rock mass, and destruction of the environment. The chemical energizer is activated by a small electrical charge which causes the blasting [2]
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