Damage Softening Model And Behavior Of Reinforced Soil Interface Based On Weibull Distribution

With its unique performance and good economic benefits,geogrid has become a kind of reinforced material widely used in practical engineering.In the overall structure of reinforced soil,the interface of reinforced soil is most prone to damage and destruction,which will cause engineering safety accidents.Therefore,It is an indispensable step to make progress in reinforced soil engineering to study the interaction between reinforced soil interface effect and reinforced soil interface.In this paper,the characteristics of the reinforced soil interface and the interaction mechanism between reinforced soil and geogrid-reinforced soil are studied from the Angle of reinforcement interface theory and numerical simulation.(1)Study on damage softening constitutive model of geogrid-reinforced soil interface.The relationship between shear stress and displacement at each stage of reinforcement soil interface drawing was deduced by the basic equation of reinforcement soil interface drawing.By introducing damage factor and assuming that it was in accordance with Weibull distribution function,a trilinear damage softening constitutive model was derived.Comparing with the existing research results,the influences of each parameter on shear stress at the reinforcement soil interface were analyzed.The evolution law of interfacial shear stress at different drawing stages and the progressive failure mode of the interfacial of reinforced soil under the action of drawing force are revealed.The results show that the trilinear damage softening model based on Weibull distribution has the accuracy of elastic index softening model and the simplicity of bilinear model,which has a certain guiding role in engineering practice.(2)Finite element simulation based on cohesive region model.The cohesive zone model was originally used to study the damage and fracture of metal interfaces.Based on the bilinear cohesive zone model,this paper establishes a separate drawing model of the transverse rib and longitudinal rib of the geogrids as well as a whole drawing model.A bond unit is set up at the interface of the reinforced soil,and the interaction between the reinforced soil interface is studied through the failure of the bond unit.The reinforcement effect of geogrid is studied through the different forces of transverse rib and longitudinal rib on soil under the action of pulling force,and the change of reinforcement effect of geogrid during the whole drawing process is analyzed.The results show that compared with the penalty function,the cohesive zone model can better simulate the interface softening and residual stress in the drawing test of geogrid.(3)Application of trilinear cohesive zone model to study the interfacial effect of reinforced soil.The bilinear cohesive region model is simple but accurate,while the exponential cohesive region model is accurate enough but complicated and not easy to converge.In this paper,turning point stress ratio and initial fracture energy are introduced in the damage evolution stage,and a trilinear cohesive zone model is proposed.The theory and constitutive equation of the trilinear cohesive zone model are studied.Based on the bilinear cohesive region model,the feasibility of the trilinear cohesive region model in studying the stiff-soil interface is verified.The results show that trilinear cohesive zone model is better than bilinear model in simulating the interaction between reinforcement and soil interface,but its implementation in numerical simulation software needs to be further studied.