| Anchoring technology is widely used in mines,tunnels,railways,slopes and other projects.Because of the anchor rod’s hidden construction,it is difficult to find defects and damages inside.It is difficult to handle when the accident happens,so the quality inspection of the anchor rod is particularly important.This paper is based on the magnetostrictive effect of anchors,and the application of magnetostrictive guided wave detection technology in the quality inspection of anchors is mainly studied by means of finite element numerical simulation.The main contents are as follows:Firstly,the dispersion characteristics of the guided wave are analyzed.Based on the propagation characteristics of the guided wave,the dispersion equation of the guided wave is established and the dispersion curves of the L-mode guided wave in the free anchor are plotted by MATLAB software.At the same time,a multi-physics coupling equation of the transduction process is established based on the principle of magnetostrictive guided wave detection.Then the finite element software COMSOL Multiphysics is used to establish the three-dimensional model of the magnetostrictive transducer.The influence of the permanent magnet bias magnetic field’s non-uniformity on the magnetostrictive transducer is analyzed.In order to simplify the calculation,a 2D axisymmetric model of the magnetostrictive guided wave detection system is established.The effects of the bias magnetic field strength at the exciting end and the receiving end and the excitation current amplitude on the energy conversion efficiency of the magnetostrictive transducer are investigated.Finally,the application of magnetostrictive guided wave non-destructive testing technology in the detection of free rock bolts and anchorage surrounding rock mass are studied.Through simulation calculation,it is verified that the magnetostrictive guided wave can determine the length of the free anchor and the position of the defect,and the influence of radial depth and axial length of the defect on the amplitude of the received signal is analyzed.At the same time,a non-destructive testing model of anchorage surrounding rock mass is established,and the influence of anchoring layer thickness,anchoring layer media,surrounding rock mass,and concrete strength on the echo of anchorage face are analyzed,and the unsaturated grouting in anchorage segment of anchorage surrounding rock mass is detected.A non-destructive testing system of anchor rod magnetostrictive guided wave is established,and the non-destructive testing of the free anchor rod is verified.The correctness of the numerical simulation is also verified. |
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