| With the gradual increase of coal mining depth and the increasing stress of the original rock,the stability of the surrounding rock is getting worse and worse,so it is particularly important for the reasonable support of deep coal roadways.At present,prestressed anchors have become the main effective support method in coal roadway support,and it has also become a consensus that the prestressed anchor compression arch prevents surrounding rock deformation and instability.Therefore,to study the effective formation and reasonable layout parameters of the prestressed anchor compression arch will have important research significance for deep coal roadway support.In this paper,the effective formation and reasonable supporting parameters of different lithological prestressed bolt compression arches are studied only from the perspective of the coal roadway.Through the combination of experimental theory and numerical simulation,the additional stress field in the surrounding rock under different anchor parameters of different lithological roadway sections is first analyzed.In order to make the analysis representative,the lithology of the surrounding rock is taken from soft coal and mud For sandstone,the prestress of the anchor rods is 40 kN,80kN,100 kN,and120kN,the length of the anchor rods is 1.5m,2.0m,2.2m,2.5m,and 2.8m,and the distance between the anchor rods is 0.4m,0.6m,and 0.8m.1.0m;and then from the analysis results of additional stress to analyze the effective formation of compression arches in different lithological roadway and the supporting displacement under the original rock stress to determine the reasonable prestressed bolt support parameters.Use the numerical simulation software FLAC3 D to perform numerical simulation,and after obtaining the numerical simulation results,import it into the post-processing software Tecplot for slicing to obtain specific data,and then use the graphics processing software Origin to organize and draw these specific data into a graph,and get additional Stress curve.See the text for specific analysis,and finally draw the following conclusions:The prestress of the anchor rod significantly affects the magnitude of the additional stress in the weak coal rock and muddy sandstone roadway and is positively correlated;when the prestress is greater than 80 kN,the magnitude of the additional stress increases slowly;although the additional stress formed in the prestressed muddy sandstone The peak stress is larger than in weak coal rock,but its decay rate is faster than in weak coal rock.The length of the anchor rod significantly affects the diffusion range of additional stress insoft coal rock and argillaceous sandstone roadway and is positively correlated.However,because the decay of additional stress in argillaceous sandstone is fast,its effective diffusion range is smaller than that in weak coal rock.The spacing of bolts affects the degree of superposition of additional compressive stress and regional continuity between the bolts in the weak coal rock and muddy sandstone roadway.In the soft coal rock,the superposition degree is good at a distance of 0.4m to form an effective compression arch;However,the sandstone has just been superimposed,and the superimposed area has very little stress,which cannot form an effective compression arch.Finally,combined with the displacement under the stress of the original rock,the reasonable parameters of bolt support are determined.See the text for details,which can provide reference significance for the actual project.Figure [59] Table [5] reference [58]... |
