A Study on the Surface Vibration Effect of CO2 Phase Transition Cracking Based on the Time-Domain Recursive Analysis Method

Abstract

Supercritical CO2 phase change fracturing technology has been widely used in rock engineering. However, the surface vibration characteristics induced by phase change rock breaking have not been sufficiently studied. In this paper, a model for calculating the surface vibration velocity induced by supercritical CO2 phase change was established based on the time-domain recursive method, and the reliability of the model was verified using LS-DYNA nonlinear finite element software; based on the model for calculating the blasting energy of a compressed gas and water vapor container, the surface vibration velocity and decay law induced by CO2 phase change fracturing and equivalent explosive blasting were compared and analyzed. The results show that the ground vibration velocity calculation model based on the time-domain recurrence method can better evaluate the ground vibration characteristics induced by supercritical CO2 phase change fracturing, and the vibration velocity decays exponentially with the fracture distance; the peak pressure of supercritical CO2 phase change is only 1/3.36 of that of explosive blasting, but the action time is 100 times longer than that of explosive blasting, and the peak vibration velocity is 1/74~1/78 of that of equivalent explosive blasting.