Experiment and application of grouting reinforcement material for broken coal and rock in roadway

Based on the problems of the development of coal and rock fragmentation in the underground fault zone, the instability of the surrounding rock of the roadway, and the high risk of coal and gas outburst, in order to realize the safe and smooth excavation of the roadway through the fault fracture zone, it is proposed to use cement-water glass (C-S) for injection. The grout material was used to implement the grouting solidification filling operation. Through testing the mechanical properties of the grouting materials, the inverted cup method and the viscosity measurement method and other related tests, the compressive strength, gel time and viscosity characteristics of the slurries with different water-cement ratios and C-S volume ratios were discussed. The effect of different ratios on the properties of grouting materials was studied, and the optimal grouting material ratio was determined in combination with the geological conditions of the Wulunshan coal mine in Guizhou. Finally, the engineering applicability of C-S materials was tested.The results show that the optimal water-cement ratio is 1:1 and the optimal C-S slurry volume ratio was 1∶0.5.After grouting and reinforcement with C-S material,the maximum residual gas content in the working face area is measured to be 2.58 m3/t,the average gas pressure is 0.15 MPa,the K1 value is 0.19 mL/（g·min1/2）,and the average S value of drilling amount is 1.67 kg/m.The various parameters of coal seam gas in the working face decrease significantly,and all of them meet the relevant requirements of the outburst prevention rules.Through the grouting solidification technology and joint support of roadway with bolts,anchor cable nets and I-beam shed,the displacement of roof and floor after coal and rock stability of roadway is measured to be 115-133 mm and the two groups move closer to 116-142 mm.Combined with the analysis of the effect of grouting on water inrush treatment,the effect of grouting on water inrush treatment and combined support is good,and there is basically no leakage of water and large rocks falling off at the working face, indicating that the grouting of C-S material Solidification has achieved good results, which can provide an effective technical approach for similar crushed formation excavation.