| With the development of social economy,the demand for coal is increasing.At present,the shallow coal in Lianghuai mining area and other major mining areas in China has been exhausted,and mining has gradually entered the deep part.Compared with the shallow part,the geological conditions in the deep part are more complex and changeable.Under different lithology,the loose and broken characteristics of surrounding rock in different section shapes and different parts of deep roadway are quite different.In Huaibei mining area,the shield machine is commonly used to excavate the deep section.Therefore,it is of great value for practical engineering to analyze the stability of different parts of circular roadway under different lithology and different depth and select reasonable support parameters.In this paper,taking the main roadway of the west wing of Yuandian Second Mine as the engineering background,the rock mass samples are retrieved from the site and the mechanical parameters of the surrounding rock are measured.The method of combining theoretical analysis and numerical simulation is used to establish the Flac 3D numerical model,and select four Typical positions(a A direction,b B direction,c C direction,d D direction),analyze the deep circular roadway in different lithology(mudstone,argillaceous sandstone,sandy mudstone),different original rock stress(8MPa,12 MPa,14MPa,16 MPa,20MPa)Fracture degree and scope of lower surrounding rock,use Origin to process data and draw tables to determine the key parts of deep circular roadways that are prone to "instability".Aiming at the main roadway in the west wing of Yuandian Second Mine,the original rock stress is 16 MPa and the surrounding rock of the roadway under different lithologies is loosened and broken.The original rock is adjusted by adjusting the length of the bolts,the distance between bolts,and the arrangement of anchor cables at key positions.The support plan is optimized,and the reasonable support parameters are finally determined.Conclusion as below:(1)As the depth increases,different parts of the roadway have different loose and broken deformations under different lithological conditions,among them,the broken range of the circular roadway gang is more obvious,the top wall rock has the smallest crushing range;Under the same position and the same depth,the deformation and swelling degree of the surrounding rock is the largest when the mudstone is lithological,and the smallest when the muddy sandstone is;under the same lithology and the same depth,the fracture and deformation of the a A part of the roadway ledge is the most significant;therefore,it is determined that the a A direction under the deep circular roadway is the key position that is prone to instability.(2)Under different lithology,when reducing the length of the anchor rod from2600 mm to 1500 mm,the displacement and breaking expansion of the surrounding rock of the roadway increase,but the broken range of the roadway does not change significantly.When the lithology is argillaceous sandstone,increase the length of the bolt,roadway displacement reduced from 73 mm to 61 mm,the reduction is not obvious.Therefore,from an economic point of view,in a muddy sandstone roadway,only a bolt length of 2000 mm is required to ensure the stability of the surrounding rock of the roadway.(3)When the lithology is mudstone and sandy mudstone,and the row spacing between bolts is reduced from 800×800mm to 400×400mm,the effect of reducing the loosening and breaking deformation of the surrounding rock of the roadway is obvious.After reducing the spacing between bolts,the surface displacement of sandy mudstone roadway is 60 mm,while that of mudstone roadway is 170 mm.Therefore,in the sandy mudstone roadway,the bolt length is 2000 mm and the distance between the bolt rows is reduced to 400×400mm to ensure the stability of the surrounding rock of the roadway.(4)After arranging anchor cables with a length of 4000 mm in key parts of the mudstone roadway,the roadway displacement is reduced from 170 mm to 132 mm,and the displacement gradient is reduced by about 41%.In sandy mudstone roadways,the displacement and breaking expansion of surrounding rock are not significantly reduced after anchor cables are arranged at key locations.Therefore,when the lithology is mudstone,on the basis of reducing the row spacing between bolts to 400×400mm,it is also necessary to arrange anchor cables with a length of 4000 mm in key parts to ensure the stability of the roadway.(5)The simulation shows that the decay coefficient of the surface deformation speed of different lithological roadways is greater than 0.04/d,and the initial deformation of the surrounding rock of the roadway is relatively stable.Therefore,the deep circular roadway in Huaibei mining area should focus on strengthening the support of the bank.The bolt(cable)support parameters finally selected in this paper can provide a basis for the support design of other deep circular roadways in Huaibei mining area,and have certain reference value for actual engineering.Figure [57] Table [15] reference [80]... |
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