Research On The Optimization Of Coal Roadway Support And Coal Pillar Parameters In The Top Coal Failure Area

This article takes the 2~#coal seam top coal destruction area project of China Coal Huajin Group Hanzui Coal Industry Co.,Ltd.as the background.Aiming at the problem that the mining roadway of 32106 coal face is seriously affected by the top coal destruction area,it adopts on-site measurements,indoor tests,theoretical analysis and Numerical simulation and other methods are used to carry out optimization research on the support of the underlying roadway and the width of the coal pillar in the damaged area.Layered security and stability under the roadway and pillar,is of great significance to improve their efficiency and production safety.Through the research of this paper,the loosening characteristics of the roadway in broken surrounding rock have been clarified,and the reasonable support method of the roadway under the broken zone has been determined.At the same time,the problem of leaving the width of coal pillars along the goaf roadway is analyzed,which has far-reaching reference significance and promotion value for similar working conditions affected by the top coal destruction area.The research in this paper has the following research results:(1)In order to determine the range of the loose zone of the surrounding rock and roof of the roadway,the RIS-K2 ground penetrating radar and the mine borehole peeping instrument were used to conduct on-site measurements of the 32106 auxiliary transportation channel.According to the waveform analysis of the six survey lines of the geological radar,it is found that the loose circle of the roadway roof is between 3.0 and 5.0m;according to the analysis of the 7 drilling holes,the thickness of the coal skin in the roadway is between 1.0 and 1.5m.The inner coal body is broken more seriously.After 1.5m,it is mostly broken coal and rock mass that collapsed in the upper layer,and the collapsed and broken layer is 2.0?3.0m.(2)Through mechanical tests on broken loose bodies of different lithologies,it is found that the higher the strength of the rock sample,the larger the breaking expansion coefficient and residual breaking expansion coefficient.However,the crushing expansion coefficient after compaction showed different degrees of decrease compared with that before compaction.The larger the Talbol index and the lower the lithological strength of the test group,the greater the reduction of crushing expansion coefficient after compaction.According to the fitting line shape of the fractal dimension after compaction of the crushed body,it is found that the fractal dimension increases after the test group is compressed,and the increment of the fractal dimension is related to lithology and Talbol power exponent.Under the same lithology,the fractal dimension increment of the test group increases with the increase of Talbol power exponent.Under the same Talbol power exponent,the lower the rock strength,the larger the fractal dimension and fractal dimension increment of each test group.(3)Aiming at the difficult problem of roadway support in the top coal failure area,the"advanced pre-grouting-bolt support"scheme was proposed.Combined with numerical simulation analysis,it was found that:(1)After the advance pre-grouting reinforcement,the plastic zone of the roadway roof is reduced from 3.5m to 1.5m,and the deformation of the surrounding rock of the roadway is effectively controlled;(2)Among the four support schemes with row spacing of 0.6m,0.8m,1.0m and 1.2m,when the shed spacing is 0.8m and the bolt row spacing is 1.6m,the support efficiency of roadway roof is high,which can meet the requirements of roadway surrounding rock deformation control.(4)Based on the elastic core theory and the calculation formula of the load estimation method,after considering the moving distance of the fracture line of the roof of the damaged layer,the optimized coal pillar width is 23m.Combined with numerical simulation analysis,it is found that when the coal pillar width is less than 23m,the roadway is seriously affected by the mined-out area,showing obvious non-uniform deformation.When the coal pillar width is greater than 23m,the stress concentration on both sides of the roadway is the same,and the asymmetric deformation is relieved,which is beneficial to the implementation of roadway reinforcement and support technology.Therefore,comprehensive theoretical calculations and numerical simulation analysis can determine that the reasonable width of the coal pillar is 23m.In this paper,there are 84 figures,34 tables,and 103 references.