Abstract: Based on the ideal elastic-plastic model of reinforced soil pull-out interface,aiming at the strain hardening and strain softening phenomena of geosynthetics during pull-out,a bilinear shear stress-displacement elastic-plastic hardening model and a trilinear shear stress-displacement elastic-plastic softening model were proposed.The pull-out process of strain hardening reinforcement was divided into three stages:elastic stage,elastic-hardening transition stage and pure hardening stage.The pull-out process of strain softening reinforcement was divided into elastic stage,elastic-softening transition stage,pure softening stage,softening-residual transition stage and pure residual stage.To verify the accuracy and applicability of the two elastic-plastic models,the predicted results were compared with the experimental results,and several classical models of pull-out interface between reinforcement and soil were introduced for comparative analysis.Based on the basic control equation of reinforcement-soil interface,the expressions of interface tension,shear stress and displacement at different stages of reinforcement of two kinds plastic deformation,strain hardening and strain softening,under pull-out load were derived respectively,which well reflect the progressive failure of the pull-out interface between reinforcement and soil.Moreover,to directly reflect the stress evolution law of the two types of reinforcement at different pull-out stages of reinforcement-soil interface,the evolution law of interface shear stress at different pull-out stages was analyzed.The results show that the predicted results of the two elastic-plastic models are in good agreement with the pull-out test data,which can better reflect the hardening or softening characteristics of the pull-out interface between reinforcement and soil,and the calculation is more simple and has better applicability,it also verifies the validity of the proposed two elastic-plastic models for the progressive failure analysis of reinforcement at the pull-out interface.In the pull-out process of reinforcement,the transition stage of the two elastic-plastic models is not obvious.The results can comprehensively reflect the progressive failure of reinforcement-soil interface with different strain types,and provide a theoretical support for the study of the interface characteristics of reinforcement-soil pull-out.