| Grouting technology as main method to improve the structure and performance as well as the bearing properties of coal/rock mass has been widely used in roadway rock reinforce and water-blocking curtain.Due to complication of Geological condition in coal/rock mass and the invisibility of coal/rock mass and uncontrollable slurry flowing during the process of slurry grouting,the splitting law and real-time identification method of fractures propagation in coal/rock mass have not been better studied.In this paper,the theory analyze,grouting experiment as well as numerical analyze were carried out to study the effect of fracture geometry parameter and interactive condition between grout hole and fractures on fracture propagation.The main contents of paper are as following:(1)Aimed at the different location condition between grout hole and fractures,RFPA-flow numerical software was used to build models of'non-intersection and intersection.Therefore,the two dimension numerical experiment of coal/rock mass with single-fracture and multi-fracture were conducted individually so as to analyze whole evolution process of fracture propagation in grout splitting,initiation pressure and fracture initiation,fracture propagation and coalescence law.(2)Self-designed three dimension similar materials grout system was developed which could real time monitor acoustic emission(AE)and nuclear magnetic resonance(NMR)signals.This system would provide the experimental basis to reveal the fracture propagation law of coal/rock mass with prefabricated fractures.(3)Grouting experiments were carried out after the similar materials with prefabricated fracture were made in terms of fracture geo'metry parameter and interactive condition between grout hole and fractures.AE acoustic emission amplitude,energy,ringing count and spatial positioning distribution were analyzed to inverse the whole process of fracture initiation,fracture propagation and fracture coalescence so as to analyze the effects of grouting splitting on fracture propagation.(4)The various porosity distribution between before-grouted and after-grouted were analyzed combined with NMR transverse relaxation time T2.Based on background of grouting reinforcement,in this paper,the grouting experimental platform was developed to reveal the effect of grouting on fracture splitting propagation in coal/rock mass with prefabricated fractures.This paper therefore claims to provide the necessary references and instructions required to the design and evaluation of grouting engineering. |
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