Research On The Bolt-grouting Supporting Technology Of Soft Rock Roadway In Qing Shuiying Coal Mine

Since1980s, NATM has got a comprehensive application in our country’s coal mines’field, and after nearly30years of development, has formed anchor and other similarsupporting structures such as anchor nets supporting and cable anchor supporting used in coalroadway. Using spray the anchor, anchor net and anchor cable supporting technique. This kindof support plays an important role in ensuring the effective control of the coal roadway.However, new Austrian method was confronted with great difficulties in the supporting of theweak rock roadway. Apart from the nature of the weak rock, the anchor cable has no rootpoint in the weak rock, thus affects the strength of the anchor cable support and the effectivecontrol of the weak rock coal tunnel. Through integrated methods of engineering geological,theoretical analysis, physical simulation, numerical simulation, site test and so on, theevolution and characteristics of deformation and failure of surrounding rock roadway of QingShuiying Colliery are studied, and the anchor net spray support+bolt-grouting supportingtechnology is proposed. The research productions have been applied successfully in project ofsupport in underground engineering, and the chief conclusions achieved are shown as follows:（1）The lithology of+786m level bottom seat strata is siltstone, its thickness is14.8m,the tested compressive strength is only1.59MPa; laboratory tests for its expansive mineralscontent are respectively: illite containing29.3%, chlorite30.7%; the measured maximumhorizontal stress is in23.74MPa, vertical stress for16.37MPa, both ratio of maximumhorizontal stress and vertical stress is1.45times.（2）With the anchor note supporting numerical analysis for the+786m level bottomheavy vehicle line,the results show that surrounding rock mass deformation damage is seriouswhen the roadway excavation to not support,and anchor play a role if the anchor note support was used,but with time still changered a lot of deformation and destruction,the anchor notestrengthen support,in tunnels developed around a thick wall bearing arch,in the same verticalpressure effect,small roadway deformation prove anchor supportingof roadway surroundingrock is the effective contol. In order to obtain the pre and post test results of the soft rock andsiltstone bolting and grouting, the soft rock particle production mechanics model according towater cement ratio of0.8mud and water was established.Theanchor note characteristic testshow that namely the peak strength bofore being bolted and grouted is11.585Mpa and after is22.22MPa. We can see the bearing capacity of soft rock increased by1.92times after boltedand grouted than bofore.（3）According to the mechanical test and theoretical analysis results, the supporting teston the+786m level bottom heavy vehicle line with the test scheme which is " anchor net ropeand anchor," then choose the reasonable support parameters and after carrying out getting theresult: one is the100d convergence deformation monitoring, its arch sinkage is21mm,sidewall sinkage is25mm, and the spray layer without any cracks and rock pressurephenomena, indicating heavy vehicle line rock has been effectively controled；two is a softrock acoustic velocity ratio increased by16%~45%after grouting, dynamic elastic modulusincreased by34%~110%, shows that after grouting soft rock’s physical and mechanicalproperties have been effectively improved; three is observed before drilling peep, groutinghole rock loose and broken, and the emergence of serious hole collapse phenomenon, and thegrouting hole rock smooth and compact, effective grout filling the surrounding rock looseningfissures, increases its compactness and completeness of the soft rock, this has played animportant role in effective control and long-term stability.Therefore, the results of this study have been tested in the+786m level bottom heavyvehicle line and the test has achieved the expected objective. Proved that soft rock tunnelusing “anchor net spray support+bolt-grouting support”is one of the most effective methods,now the method has been widely used in all soft rock roadway and chamber of the+786mlevel bottom, meanwhile it also provides a good reference for other mine’s soft rock roadwaysupport.