| Because the prestressed anchor cable is buried deep underground and suffers from environmental erosion for a long time,the degradation of the bond property of the anchor cable after corrosion is more prominent.Existing relevant studies mainly analyze the influence of conventional rust-free anchoring section bonding performance by carrying out physical model tests and theoretical studies,while there are few researches on the bonding performance of cable in corrosive environment.Therefore,against the background of chlorine salt erosion environment,this thesis adopts the method of combining experimental research and numerical simulation to study the degradation law of the bonding property of the anchoring section of cable.The main work is as follows:(1)The corrosion characteristics of anchor cable and the failure mode of anchor solid drawing are clarified.The test considered different corrosion rate and bonding length of anchoring section,and carried out the tensile test of corroded anchor cable under chlorine salt erosion environment.The results showed that under the same bonding length,with the increase of corrosion degree of the anchor cable,the corrosion products on the surface of the cable body also increased,more pits were distributed in a larger range,and the maximum cross-sectional area loss rate reached 7.19%.The increase of bond length has a greater impact on the failure of specimens than that of corrosion rate.With the increase of bond length,the failure mode of specimens is split failure.With the increase of corrosion rate,the failure modes of specimens with short bond length are mainly pull-out crack failure and pull-out split failure.(2)The degradation law of bonding property of corroded anchor cable is expounded.The bond stress-slip curve of the anchor cable was obtained according to the drawing test data,and the distribution and change of the real bond stress on the surface of the anchor cable before and after corrosion were compared.The influence of the corrosion rate and bond length on the average bond stress of the anchor cable was obtained.In the early stage of corrosion,the bond stress of the anchor section would be increased within a certain range,with an average growth rate of about 6.5%.Then,as the corrosion rate continues to increase,the bond stress presents a linear decrease trend,and the bond strength decreases by 32.2% on average.Under the same corrosion condition,the bond stress of the cable decreases linearly with the increase of bond length,and decreases by34.9% on average.Three main characteristic stages of the bond stress-slip curve of the anchor cable are revealed,and the bond stress-slip constitutive relationship of the corroded anchor cable is established,which is in good agreement with the experimental results.(3)The stress deformation characteristics and damage change process of anchor solid of corroded anchor cable are revealed.The cohesive force contact model was adopted in ABAQUS to obtain the surface stress and strain of the entire anchor cable during the drawing process.With the increase of corrosion rate,the surface stress and strain of the entire anchor cable gradually decreased,and the transmission direction was from the loading end to the free end.The stress and deformation of anchor solids were obtained.With the increase of corrosion rate,the stress and strain of grouting body and surrounding rock also showed a decreasing trend.The damage evolution process of specimens under different corrosion conditions is analyzed.With the increase of corrosion rate,the damage zone of specimens is more widely distributed and the damage is more serious in the drawing process.Compared with the experimental results,the numerical simulation bond stress-slip curve is obtained,and its average error is controlled within7.45%,which proves the rationality of the numerical simulation method and the correctness of the fitting constitutive mentioned above. |
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