Study On Stress Wave Transfer Law And Mechanical Response Characteristics Of Anchor Under Dynamic Load

As the main structure of bolt support,anchorage support has high bearing capacity and adaptability to the deformation of roadway surrounding rock.It plays an important role in the support of tunnel,coal mine and other underground engineering structures.On site,the prestressed anchor is subjected to the dynamic load caused by blasting and mining,and the prestressed anchorage support bears the typical static and dynamic load coupling effect,which makes the failure characteristics of the anchorage support more complex.In order to reveal the failure characteristics of the anchored supporting under the coupling action of dynamic and static loads and the influence law of dynamic load stress wave.In this paper,the dynamic load impact test and static pull-out test of different prestressing force,impact times,impact energy and impact frequency are carried out by theoretical analysis,impact test and numerical simulation.The stress wave transmission law,axial force loss law and failure characteristics of the anchorage support are studied.The main conclusions are as follows.(1)The magnitude of stress wave in elastic rod is related to the magnitude and direction of static load.The magnitude of stress wave in elastic rod under gradient static load is related to the static load difference between the incident end face and the calculated end face.When the anchorage support is subjected to compressive stress wave,the peak value of stress wave in the surrounding rock of anchorage section is the largest,and the peak value of stress wave in the bolt of free section is the largest.(2)In the range of 15MPa-30MPa,with the increase of prestress,the peak value of stress wave in Anchorage surrounding rock increases gradually,and the attenuation speed decreases gradually.The results show that with the increase of impact times,the damage of surrounding rock increases and the prestress decreases.The results show that when the prestress is 17Mpa,the residual value of the axial force of the bolt is the largest,and the dynamic adaptability of the bolt is the best.The failure characteristics of impact specimens include shear failure at the impact end,combined tensile and shear failure at the free end and fracture wave failure at the middle.(3)The drawing curves of impact specimens and non-impact specimens are similar,which can be divided into stable increase stage,rapid decrease stage and residual balance stage.In the range of 10MPa-30MPa,with the increase of prestress,the pull-out strength of the impact specimen first increases and then decreases,and reaches the maximum at 17MPa.The pull-out failure characteristics of the specimens are bolt pull-out failure,surrounding rock pull-out failure,surrounding rock and anchorage agent pull-out failure.(4)When the impact frequency is in the range of 50Hz-250Hz,with the increase of impact frequency,the stress amplitude in the anchorage support decreases gradually.The damage degree of the specimen is inversely related to the impact frequency.When the impact velocity is between 0.5m/s and 1.0m/s,the peak value of stress wave increases linearly with the increase of impact velocity.With the increase of impact velocity,the failure degree of the specimen increases.Figure[56]table[5]reference[96]...