Experimental Study On Reinforcement Of Expansive Grouting Material In Fractured Surrounding Rock Of Coal Mine Roadway

At present,in crushed surrounding rock of coal roadway grouting support,most of the pure cement slurry grouting reinforcement,the low strength,drying shrinkage,illiquid and bond issue such as difference of coal and rock,the grouting effect is poor,affect the safety of the tunnel,as a result,around the modified pure cement slurry performance defect,the laboratory test and numerical simulation,the method of expansion of independent preparation of grouting material proportioning,grouting reinforcement and anchorage system characteristics research,and then find well the best proportion of modified pure cement slurry defects so as to strengthen the grouting effect,improve the safety of the tunnel.(1)Experimental study on ratio.By orthogonal test method to the expansion of the grouting material of expansive agent,dosage of water reducing agent and early strength agent dosage of 3 factors 3 levels orthogonal experiment design,design of expansion agent content is 5%,10%,15%,early strength agent content is 3%,4%,5%,water reducing agent content is 0.4%,0.8%,1.2%,through the analysis of different expansion agent,early strength agent,water reducing agent dosage levels,serum fluidity,viscosity,setting time,drainage rate,compressive strength and expansion ratio and expansive force,a total of seven nature characteristic,the influence of the final comprehensive balance method is used,The optimal ratio of the expansion material is 10%,5%and 1.2%respectively.(2)Experimental study on grouting reinforcement.Through independent design simulation of grouting device,to carry out the broken coal and rock expansion of grouting material and pure cement grouting consolidation tests,by comparing the broken coal and rock before and after grouting reinforcement is the size of the 7 d and 28 d compressive strength,it is concluded that to restore broken the strength coefficient of expansion than pure cement grouting material high 0.15,0.27,respectively,for rock mass is high 0.1,0.18,respectively,to verify the rationality of the best ratio of grouting material.(3)Drawing test of anchorage system characteristics.On the one hand,the stress test of the anchoring system was designed.The anchoring bolt was injected with expansion grouting material and pure cement slurry through drilling hole,and the drawing test was carried out on it.Drawing design of anchorage system,on the other hand,numerical simulation,simulated under the condition of single coal and rock lithology,expansion pure cement grouting material and anchor bolt respectively,analysis of bolt axial force and serous fluid shear stress and the characteristics of the surrounding rock stress three aspects,it is concluded that coal lithology in drawing force 100 kn,expansion of the grouting material in maximum bolt axial force,serous fluid shear stress and stress of surrounding rock,respectively,compared with the pure cement slurry,high 0.0003 MPa,0.0001 MPa and 0.01 MPa.At the drawing force of 150KN,the drawing force is 0.00001mpa high,0.0008mpa low and 0.012mpa low.At the drawing force of 200KN,the drawing force is 0.0001mpa high,0.001mpa low and 0.02mpa low.The lithologic law of rock mass is similar to that of coal.lt is concluded that the anchoring effect of expansion grouting material is better than that of pure cement slurry.Finally,the expansion grouting material is applied to the field support test of the roadway in the alighting field of the track in the east wing of anju coal mine.By analyzing the deformation,reinforcement and bolt stress of the surrounding rock of the roadway strengthened by grouting,it is concluded that the slurry of the expansion grouting material can be effectively applied,which provides a security guarantee for the stability of the surrounding rock of the roadway.