Abstract:
With continuously increasing urban construction, more underground projects require the breaking of rocks near sensitive areas, such as hospitals, schools, and residential areas. On one hand, since conventional blasting that uses explosives has a negative impact on the safety of the surrounding buildings and brings about noise and flying rocks, the use of explosives are sometimes not allowed. On the other hand, the efficiency of mechanical rock excavation is very low, resulting in a low speed of rock excavation and high operation cost. In view of this situation, techniques that incorporate carbon dioxide phase transition fracturing have been tried in rock fragmentation in complex and sensitive environments such as those mentioned above. Furthermore, carbon dioxide phase transition fracturing is also regarded as an ideal substitute for the explosives in the field of coal permeability improvement. As an environmentally friendly rock-breaking technology, carbon dioxide phase transition fracturing has the advantages of high excavation efficiency, low vibration, and no pollution. In recent years, it has become a hot topic in the field of rock breakage and excavation. Research on this gas explosion technology has been developed rapidly and several useful progresses were made in this technology using theoretical analysis, experiments, and numerical simulations in a wide range. Through investigation and analysis of existing research results, the rock breakage mechanism of carbon dioxide phase transition fracturing was elaborated. A review was also presented on the fracturing load characteristics and its testing method. The main factors influencing the fracture load and fracture result were recapitulated. This review also analyzed the harmful effects of this new technique and generalized the applications of this technology in different fields. Finally, the problems and future challenges of carbon dioxide phase transition fracturing were discussed. The review aims to provide a reference for the theoretical research, generalization, and application of carbon dioxide phase transition fracturing technology.