Analysis Of Mechanical Characteristics Of Bolt Based On Wavelet Function

Anchoring technology is a way to support engineering structures by rods composed of steel bars or high-strength steel strands embedded in rock and soil.Anchoring technology closely bonds the rock soil and the engineering structure together,and mainly relies on the shear strength transfer tension between bolt and anchorage interface to improve the strength of rock and soil mass,which has the advantages of low cost,simple operation,good supporting effect and wide application.The effect of bolt support plays an important role in the stability of engineering construction,and the mechanism of force transfer in anchor anchorage section is the key problem of anchorage design.In the current relevant specifications,the assumption of uniform distribution of shear stress is adopted for the anchor design.Theoretical research and engineering practice of many domestic and foreign scholars show that this assumption is unreasonable.The shear stress distribution of the anchorage section is affected by the properties of the anchoring interface and the pulling load.Exploring the mechanical properties of anchor bolts is of great significance for optimizing bolt design.However,the existing research results pay more attention to the study of the ultimate bearing capacity of bolts.The internal force distribution of the bolts under working conditions,the pull load displacement curves and the bolt stiffness are less studied.It is not possible to accurately reflect the mechanical properties of the anchoring interface and guide engineering practice.This paper studies the bolt,including the following aspects :(1)According to the mechanical properties of the bolt interface,a constitutive model of shear stress-displacement of bolt interface is established based on wavelet function.The equations of the load-displacement curves of the full-length bonded bolt is deduced based on the mechanical differential equations of load transfer of the bolt.The internal force distribution of the bolt from elastic to elastoplastic slip is solved,and corresponding numerical calculation methods and steps are proposed.The feasibility of the method is tested by comparison with the pull test data.(2)Based on the stress analysis of the full-length bonded bolt,the drawing load-displacement curve of the free-segment prestressed bolt is obtained,and analyze the influence of the length of the free section and the stiffness of the bolt are analyzed.(3)The critical anchorage length of the bolt is analyzed,and two methods for calculating the critical anchorage length areproposed,and corresponding engineering suggestions are proposed.(4)The bolt stiffness coefficient is analyzed,a new formula for bolt stiffness calculation is proposed,and the influencing factors of bolt stiffness are analyzed to provide reference for bolt design and finite element simulation.