Stability Analysis And Synergistic Effect Study Of Surrounding Rock Of New-type Tension-dispersed Bolt-supported Roadway

At present,China’s coal mines are gradually turning to deep mining,and the surrounding rock of deep roadway has large deformation displacement and long duration under the environment of high geostress,high geotemperature,high seepage pressure and strong mining disturbance,the traditional tension concentrated bolt is unable to adapt to the large deformation failure of the surrounding rock of deep roadway because of the shear bearing capacity provided by its structural defects,the superiority of its support can not be reflected in deep roadway.In order to adapt to the deformation and failure characteristics of surrounding rock under the complicated geological conditions of deep roadway in China,to improve the ultimate bearing capacity of Anchorage body,to reduce the stress concentration in Anchorage section,to enhance the shear failure resistance of Anchorage body,and to improve the effect of Anchorage support,a new type of tensile dispersed bolt is developed to adapt to the large deformation of deep surrounding rock.At present,the pullout tests of the new tensile dispersed anchor under confining pressure and shear have been carried out in laboratory,and the superiority of its properties has been verified.But there is a big difference between the laboratory experiment environment and the actual engineering geological environment.In the field engineering environment,the new type anchor rod is also affected by many factors such as mining disturbance stress,it is not known whether the new tension dispersive anchor still has its unique superior performance after it is applied in engineering practice.In view of this,this paper will focus on the actual engineering application effect of the new tensile dispersed anchor,using numerical simulation,indoor similarity test and other scientific and technological means,the stability analysis of the surrounding rock and the study of the synergetic effect are carried out.The main research conclusions are as follows:(1)Through numerical simulation and indoor simulation,it is found that the new tensile dispersed anchor has higher elongation performance than the common anchor in practical engineering application,its anchorage performance is better than that of common stress-concentrated bolt,which is suitable for supporting large deformation surrounding rock.(2)The extension effect of the new tensile dispersed bolt and the surrounding rock deformation and displacement produce a continuous synergetic deformation,with the effect of time,the timehistory curve of the displacement of the new type bolt is similar to that of the surrounding rock.(3)The change of anchoring parameters has a certain influence on the stability of surrounding rock of roadway.The results of numerical simulation show that the distance between bolts,the length of bolts and the length of bolts have great influence on the stability of roadway surrounding rock,but the diameter of bolts has no obvious influence on the stability of roadway surrounding rock.There is an optimum parameter ratio among the anchorage parameters of the new type of tension dispersive anchor.The optimum anchorage parameters are 2.5 m in length,22 mm in diameter,0.5 m in Anchorage length and 0.6 m in row spacing.(4)The shear stress of the anchorage interface reaches its maximum value at about 0.1 m from the end of the anchorage segment,and then decreases gradually along the length of the anchorage segment.(5)When the anchorage parameters change,the peak value of anchorage shear stress of boltcement slurry interface will change,and the shear stress of Anchorage interface will increase with the increasing of the distance between bolts When the length of the anchor rod is fixed,the shear stress of the medium and short anchor rod increases with the length of the anchor rod,however,the shear stress of the interface decreases with the increase of the anchorage length.(6)Under the influence of strong mining disturbance,the axial force of the free section of the new type of tension-dispersed anchor is roughly equal,while the axial force of the anchored section decreases in a negative exponential law.