Analysis of mechanical properties of flexible bolt and its engineering application

In order to analyze the mechanical properties and support technology research of flexible anchor rods,static load mechanical properties testing of flexible anchor rods is conducted in the laboratory,and the conversion relationship between torque and preload of flexible anchor rods is analyzed.Reasonable preload parameters are determined,and underground engineering applications are carried out.The results show that flexible anchor rods have high bearing characteristics,and the static load tensile force displacement change process can be divided into initial bearing stage,quasi elastic stage in the yield strengthening stage and the fracture stage,the average yield strength is 320 kN,and the average bearing capacity is 357.23 kN.The high bearing performance of flexible anchor rods can achieve the purpose of low density and large row spacing strong support,inhibit the deformation of shallow roof rock layers,give full play to the bearing performance of deep rock layers,and form a stable continuous bearing beam.The engineering application shows that the flexible anchor rod reaches stability at a distance of about 100 m from the working face,and its bearing level is significantly improved compared to the ordinary anchor rod.After being stabilized,the bearing capacity ranges from 113.5 kN to 127.4 kN,which is from 47.9% to 55.7% higher than the initial preload.After excavation,the initial deformation of the roadway is small,and the overall molding effect is good.The maximum inward deformation of the two sides of the roadway is 17.5 mm,and the maximum displacement of the roof and floor is 13.7 mm,indicating that flexible anchor support can effectively control the deformation of the roadway surrounding rock.