Liquid CO2 Phase Change Fracturing and Vibration Monitoring in Roadbed Slope Excavation

Abstract In order to analyze the vibration impact of carbon dioxide fracturing tube blasting red sandstone, combined with the engineering conditions and surrounding environment of Anqing High-tech Zone, the rock-breaking blasting plan is carefully designed. The fracturing tube is arranged in two rows, the first row has 23 holes with a spacing of 1.5m, and the second batch of holes has 22 holes, which are arranged in a quincunx pattern with a distance of ‘1.3m between the front and rear rows. And design the corresponding vibration signal monitoring test to study the crack propagation caused by blasting, the attenuation law of vibration and its frequency spectrum distribution. The results show that after blasting, there is a relatively smooth crack in the plane area of the fracture zone 7m away from the critical surface. The width of the crack is between 20-40cm. The vibration velocity of the measuring point decays rapidly with the increase of the vibration source distance, and the vibration velocity decay curves in the X and Y directions are basically the same. Spectrum analysis shows that the main frequency band of each sub-velocity is generally below 100Hz, and the main vibration frequencies in the X and Y directions are concentrated in 30∼60Hz. The main vibration frequency band of the rock-breaking blasting vibration signal has little correlation with the direction and propagation distance of the vibration signal. And compared with the analysis of emulsion explosives, it is found that the particle vibration speed caused by the emulsion explosive rock-breaking blasting is much greater than that of the liquid CO2 fracturing tube rock-breaking blasting, indicating that the use of liquid carbon dioxide to break the rock can effectively reduce the vibration generated by blasting.