Hydraulic fracturing technology and its applications in strata control in underground coal mines

Hydraulic fracturing technology applications in strata contral in underground coal mine are mainly in hard roof weakening and stress relief in rocks surro unding roadways with high stresses. Based on the analysis of current hydraulic fracturing theories,the achievements of hydraulic fracture propagation obtained by real tr iaxial hydraulic fracturing test system were introduced.The latest developments of hydraulic fracturing in underground coal mines,involved in conventional and direction al fracturing methods,fracturing equipment and technologies,monitoring instruments and methods for fracturing effect,were presented emphatically.The hydraulic fracturi ng case studies of hard roof weakening in working faces,and stress relief in gateroads affected by multiple mining dynamic pressure were introduced,and the fracturing effects were evaluated.Finally,the suggestions and development direction for hydraulic fracturing were put forward based on the characteristics of surrounding rock in u nderground coal mines.