Study On Influence Of Roof Difference And Anchor Parameters On Prestress Spreading Of Anchor

With the continuous development of the coal industry,bolting support technology has made considerable progress.Accordingly,the anchoring theory has gradually improved.In the course of the development of the bolt support theory,the researcher discovered the active support of the prestressed anchor,and used the prestress of the anchor to change the nature of the stress state of the rock,so that the interior of the rock formation has a certain carrying capacity.The anchors achieve the effect of controlling the stability of the roadway roof.In this paper,the 90111 transportation trough of Majunyu Coal Industry was used as a geological prototype.The geological characteristics of roadway surrounding rock were investigated on site,and the physical and mechanical properties of rocks were determined in the laboratory.Based on the existing bolt support theory and the prestressed bolt support mechanism,based on the actual geological conditions of the site,the effect of the roof support caused by the difference of the roof and the effect of bolt support parameters on the prestressing diffusion effect of the bolt The impact is taken as the main research content of this article.The specific content and conclusions are as follows:1.Through the induction of several common roadway support theories,the deformation characteristics of surrounding rock of roadway and the mechanism of prestressed bolt support are studied.It is concluded that the prestress of the bolt can provide supporting resistance for the surface of surrounding rock and form a certain load carrying capacity.The composite beam structure,improve the mechanical parameters of the surrounding rock,improve the stress state of the surrounding rock,improve the deformation performance of the surrounding rock,and control the harmful deformation of the surrounding rock.2.Through on-site investigation,five different types of roadway roofs have been divided for the test roadway roof,which is based on the different layers of the weak sandwich in the K₂ limestone roof,which is the mudstone is located at the roadway roof 0m,0.2m,0.4m,0.6m and 0.8m.At m,and according to the theory of layered roof key layers,theoretical calculations were made for different layers of mudstone,and it was concluded that mudstone is located 0.2m above the roof,and the maximum direct roof deflection is within the critical layer range.At this time,the possibility of the occurrence of top plate separation is the biggest,security is low.3.The results of theoretical calculations are verified by numerical simulation of the situation that the tunnel roof is most likely to be separated.When the mudstone is located0.2m above the roadway roof,the effect of the bolt prestressing diffusion is the worst,which is the difficulty of support is greatest.4.Through numerical simulation,it is found that the pre-stress diffusion effect of the anchor rod?diffusion rate?has a logarithmic relationship with the prestressing force of the anchor rod,and increases with the increase of the prestressing force;the pre-stress diffusion effect of the anchor rod has a linear relationship with the distance between the anchor bolts.With the increase of the distance between the rows,the diameter of the anchor rod and the length of the anchor rod have little influence on the diffusion effect of the anchor prestressing force,and do not have significant characteristics.Through numerical simulation,the mathematical expressions of the pre-stress diffusion effect of the anchor and the parameters of the anchor are obtained:k=0.0807+0.3379ln K-0.637H-0.0002?D²+D?-0.0162?L²+L?5.Through the monitoring of the mine pressure during the excavation and recovery of the two supporting schemes,it is found that the optimized support scheme plays an effective role in controlling the deformation of the roadway surrounding rock during the two phases,and during the mining of the working face,the prestressing force The bolting effect is more pronounced.