Study On Surrounding Rock Grouting Reinforcement Technology And Its Application In Fully Mechanized Caving Face Of Guandi Mine

When through geological fracture zone of the fully mechanized caving face,it is very easy to appear the problem of coal wall spalling and roof caving.In this paper combined numerical simulation,laboratory test and field measurement.The technology and application of grouting reinforcement in fully mechanized caving face has been studied,the main conclusions are as follows:For the fully mechanized caving face geological fracture zone prone to problems of coal wall,frame before falling,comprehensively using the methods of numerical simulation,laboratory experiment and field test combined with the study on the reinforcement technique and its application in fully mechanized caving working face surrounding rock grouting,mainly draws the following conclusions:(1)According to the characteristics of coal mining,calculation model has been establishedin the plastic zone surrounding.Through theoretical analysis and derivation,analytical solutions has been obtainedin the stress distribution surrounding rock.(2)The strata structure of coal bed roof has been analysisedby borehole peep.Within the scope of its immediate roof 4 m,coarsesandstone,low overall cementation,large cranny channel very obvious,crack very development;4 ~ 4.8 m its fissure has been decreased,but still joints and fractures than any other strata development,mainly sandy mudstone;Between 4.8 ~ 8.8 m rock breakage is still serious,big fractures clearly visible,8.8 ~ 9.4 m layers become dense,crackdevelopment,mainly fine sandstone;Limestone appear in 10.0 ~17.3 m,can determine the period of rock ask the basic roof of coal seam,delamination phenomenon no appear,the fracture is not obvious.17.5 ~19.4 m rock crushing more apparent,rock integrity poor.19.4 ~ 20.6 m with sandstone and mudstone,lateral fissure development very much.Surrounding rock strength has been measureed for 10 m range area coal roadway in situ of Guandi mine,the average strength of 8coal seam is 14.67 Mpa,by analyzing the curve of rock strength can be concluded,the strength of the coal rock fluctuate greatly with the same measuring point,illustrates the strata in the direction of the test integrity is poorer,crack development,the result is consistent with the results of peek.(3)In order to correspond with the actual grouting engineering,the grouting experiment system equipment has been researched and developed,mainly including grouting experiment container,in-situ stress load,voltage stabilizing system,hydraulic pressure,voltage regulation system and grouting system.The paper has been did two experiments,respectively load 1.0 MPa and 1.5 MPa geostress and adopt the intermittent grouting process.The first time grouting experiment,grouting pressure is 8 mpa,grouting quantity is 100 ml,the second grouting pressure up to 9 mpa,grouting quantity is 100 ml,whin the third grouting pressure decreases,and the grouting volume increases,the fourth and fifth grouting pressure stable in 8 mpa,grouting quantity increasing.Three times before the second grouting experiment,,groutingquantity decreases,the fourth grouting quantity increased to 200 ml,the fifth grouting pressure dropped to 100 ml,grouting pressure is 10 mpa for the first time,the rest of the grouting pressure is stable at about 9 mpa.Under different stress conditions,the change of the grouting pressure and grouting amount,reflect the formation of seepage channel and ground stress related.(4)In this paper,by using FLAC numerical simulation software,the variation characteristics of different pore sizes and different grouting pressure has been researched,the result shows: we can increase appropriately the radius of grouting holein the grouting,in order to increase the radius of slurry seepage and seepage,and increase the size of the network of concretion body skeleton.Increase of slurry seepage grouting pressure,grout in seepage channel penetration radius is increased.(5)Full-mechanized caving mining face of roof and broken easily produce leakage risk with the geological structure.The tip-to-face roof caving structure analysis model has been establishedaccording to the characteristics of building roof.Through the theoretical analysis shows :1)the caving arch arch feet after balance needed for RA,HA increases with the increase of load Q;2)Its favored caving arch stability with the narrow end distance;3)improving the support working resistance can reduce the face roof caving;4)in view of the 28416 working face,if don't take measures,the tip-to-face roof caving height 2.8 m in geological fracture zone.Grouting reinforcement can improve the strength of fracture zone,then the overall structure of the tip-to-face roof into a medium structure.According to the characteristics of longwall mining working face,the tip-to-face roof "beam" structure analysis model has been build.According to the actual,geological fracture zone h > 2.0 mhas been determined when the thickness of grouting reinforcement in the28416 working face mining,.(6)Numerical analysis shows,if the geological fracture zone did not develop to coal seam,the tip-to-face roof above the damage area and geological fracture zone will link up when top-coal thickness less than 2m.To prevent tip-to-face roof caving,the top roof must be groute reinforcement.When the top-coal thickness greater than 2 m,face failure area can not link up the top of the geological fracture zone,will not face big damage.The early supporting force,bring pressure to move and strengthen the protection can be used to push through the geological fracture zone,the calculation results are in conformity with theoretical analysis.(7)Fully mechanized caving face has been grouted by the cement-sodium silicate and chemical grouting.According to the characteristics of the geological fracture zone of surrounding rock of auxiliary transport soft,and marithan grouting reinforcement are obtained with particle composition test of rock sample.28416 auxiliary lane enter the combination of grouting and the frame before grouting grouting reinforcement scheme and implement has been adopted,the number of grouting hole,the geometric parameters of grouting holes,grouting parameters,grouting process and grouting equipment has been determined.(8)Based on the investigation to the grouting effect of full-mechanized caving 28416 mining face,the results show that the grouting area marithan fill fully,borehole wall smooth,grouting area has cementation for whole,grouting concretion body and contact between coal wall,basic not mine coal wall and tip-to-face roof pressure,roadway overallsituation is good,that study of the grouting parameters is reasonable and feasible.