Research on fracturing of hard roof in Shaqu No.1 Coal Mine induced by liquid carbon dioxide phase transition
GUO Yu
Abstract：In coal mining,hard roof conditions often lead to challenges such as excessive suspended roof at roadway ends,posing safety risks like gas accumulation and large-scale roof falls.Focusing on the 4501 working face hard roof of the Shaqu No.1 Coal Mine,this study applied liquid carbon dioxide phase-transition fracturing technology to fracture and control suspended roofs.The development of crack expansion in the borehole was also observed by a speculum to evaluate the fracturing effect.Field practice has shown that multiple cracks were observed in the drill holes to expand,penetrate and extend,and the three-cycle detonation program designed in this paper effectively broke up the roof rock and accomplished the goal of cutting the roof.Further studies revealed that the triangular hole placement scheme was more effective than the rectangular hole placement scheme in terms of fractu-ring.Ring-shaped crushing zone at the location of the hole after blasting,with microcracks expanding in the direction of the main fissure.The fracture pattern and the degree of development of the drill hole is affected by the wall lithology,detonation method and other factors.Optimize fracture connec-tivity by controlling the detonation sequence,with better results for double-hole joint rock blasting.
Keywords：coal mine suspended roofCO2 phase-transition fracturingrack propagationcyclic blastingrock fracturing technology
Publication Date：2025-04-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：7( 13-19 )