Comparison analysis of ground vibrations induced by CO2 gas fracturing and explosive blasting

Cardox tube system(CO2 gas cracking technology) is conductive to reducing the side effect of vibrations in rock excavation. To quantify this reducing effect, field tests of gas cracking and explosive blasting were conducted at the foundation pit of a nuclear power plant. At the same time, the ground vibrations induced by the two methods were monitored respectively. On the basis of energy equivalence, the phase transition energy of liquid CO2 was calculated and converted to emulsion explosive mass with the same amount of energy. By introducing a PPV(peak particle velocity) ratio of the two methods, the attenuation characteristics of ground vibrations were compared and the considerable discrepancy between the PPVs was revealed, so as to provide guidance for the optimization of rock excavations and technical configurations of Cardox tube system. It is observed that, under the same equivalent charge amount, the vibrations induced by CO2 gas fracturing are much less than those by explosives, and attenuate more rapidly. Generally, the latter are at least 5 times more than the former, and the difference keeps growing with increasing the distance and decreasing the equivalent charge amount, which means that Cardox tube system is more efficient in vibration reduction in middle to far areas from the rock excavation point, and especially efficient in local and small-scale rock excavating. It is also indicated that the explosive consumption per unit volume of rock is about 5 times the equivalent value of Cardox tube system, as is the reason for the remarkable discrepancy in PPVs by the two methods. © 2021, Science Press. All right reserved.