Structure Response And Non-linear Analysis Of Asphalt Pavement Based On Full-scale Loop Test

Can the structure analysis method describe objectively the real service status of the pavement is the main issue for design of asphalt pavement.Due to the complexity and variety of pavement materials,the responses of pavement structure under the action of vehicle load and environment condition show obvious non-linear characteristic.Accurately obtaining these responses and taking full account of it during calculation is the key to ensuring scientific and reasonable structural analysis.Currently used methods are linear elastic layer system and structural layer modulus method,they can not describe the nonlinear behavior and mechanical response during service.So the structure analysis and calculation based on these theories are limited.Based on above reasons,full-scale loop road test,model test,material test and mechanical analysis method of pavement were used to study the real response of pavement structure,nonlinearity of pavement materials and structure analysis method.The main research contents are as follows.The real mechanical response of pavement structure was studied by full-scale loop road test.The actual service environment and mechanical response law of asphalt pavement structure were obtained by sensor testing technology.The temperature change description model was established.The temperature parameter determination method used for structural analysis was given,and the temperature dependence and load dependence of the true mechanical response were revealed.The results show that the Bigasusian function can effectively characterize the atmospheric temperature and the internal temperature of the structure.It can be used as a mathematical model to describe the temperature distribution characteristics.The mechanical response of deflection,stress,strain and etc.have significant temperature dependence.In addition to the temperature increase and decrease caused by temperature rise and decrease,the mechanical response direction will be changed.Based on the full-scale loop road under zero load test results,the power function is used.The three mechanical response parameters were used for temperature correction.At high temperatures,the load-dependence and the nonlinear response of deflection,stress,and strain are much significant.Based on the model tests,the real response law of asphalt pavement structure was studied.Similarity theory was used to design the asphalt pavement structure model test,and a real test method for the pavement structure based on the model test was proposed.The load and temperature dependence of the strain response between the surface and the layer was revealed,and the interlayer condition used for the structural analysis was given.The results show that when the plane size of the model test is 100 cm in diameter,the model structure has good similarity with the original structure.The model test method has good parallelism,good reproducibility and high reliability,and can be used as a real road structure.There are three distinct mechanical response characteristic points on the surface of cement stabilized macadam and asphalt concrete model: the maximum point of compressive strain,the boundary point of tension and pressure and the peak point of tensile strain.Obvious characteristics are existed in these two models.The inter-layer strain response of homogeneous and heterogeneous material structures has a certain temperature and load dependence.In the structural analysis,continuous hypotheses can be used between asphalt material layers and semi-rigid material layers.A semi-continuous,semi-slip hypothesis should be used between the asphalt material layer and the semi-rigid material layer.Based on the material tests,the nonlinear properties of the full-scale loop road surface material were studied.Through the analysis of the structural behavior of materials,the temperature and load dependence of asphalt mixture and semi-rigid materials were revealed,and the modulus-dependent models of pavement materials based on stress or strain,temperature or strength were constructed,and the cross mechanism from material modulus to the structural layer modulus is built.The structural layer modulus method for structural analysis was given.The results show that the asphalt mixture has obvious temperature and load dependence,and the dynamic modulus dependent model of asphalt mixture based on the expression of temperature and strain parameters can be constructed.The semi-rigid material has certain strength and load dependence and the semi-rigid material modulus-dependent model can be constructed based on stress and parameters expression.The Mises equivalent stress and the equivalent strain can be used to coordinate the indoor single stress state and the on-site complex stress state,to achieve the span of the modulus of the material to the structural layer modulus,and the method of determination between layers can be verified according it.Based on the analysis theory of road mechanics and the real response behavior,the nonlinear analysis method of asphalt pavement structure was studied.Based on the analysis of the real response behavior of the pavement structure,the basic theory of nonlinear analysis of asphalt pavement was established,and the analysis method of asphalt pavement structure based on material nonlinearity was proposed.The effectiveness of the method was verified based on the measured results of the full-scale loop road test.The results show that under the assumptions of material nonlinearity,interfacial bonding conditions,structural response uniqueness,and most adverse temperature,an asphalt pavement structure analysis method based on material nonlinearity can be established,which can simulate the nonlinear characteristics of real responses better.Modulus values,stress states,calculated temperatures,and calculated point positions have a significant effect on the nonlinear analysis results.There is a consistent trend and correlation between the results of the analysis and the true response of full-scale loop road.This method has certain scientificity and rationality and it can be used as a calculation method for the nonlinear analysis of asphalt pavement.This study obtains the real response law of pavement structures and the nonlinear properties of materials,and an asphalt pavement structure analysis method based on the nonlinear service behavior of pavement structures is proposed.The research results can further improve and develop the theory of asphalt pavement structure analysis and provide foundation for building durable asphalt pavement.This reaearch has a certain degree of academic significance and application value.