Numerical Simulation Of Early-age Mechanical Behavior Of Concrete Pavement Due To Temperature And Humidity Effect

In recent years,a new theory about jointed plain concrete pavement(JPCP)shows that early age behavior has significant impact on the performance of its service,and early age parameters can be a link to consider the effect of construction,material,structure,environment together on pavement performance,and make it possible to analyze pavement mechanical behavior in a whole life from early age to service life.All of these are very useful for improving theory and practice of JPCP.But the neglect of the feature of three dimensional pavement thin slab,interaction and evolution of early age behaviors may lead to a great simplification and many defects in application.Consideration of the above mentioned problems,the research goal of this paper is to improve the early numerical simulation program of early age solidification evolution of concrete pavement.The new numerical simulation program has more functions including consideration of slab length,size and moisture effect.And main target is to conduct numerical simulation of early age mechanical behavior study of cement concrete pavement under the improved program on temperature and moisture fields.The specific research work and achievements are as follows:Firstly,we investigate the early numerical simulation program and make effort to improve it.In comparison with the concrete shrinkage model at home and abroad,early age autogenous shrinkage and drying shrinkage of concrete integration model which is created by Zhang Jun tsinghua university is choosed.And using Fortran software programmed in to contract model,and validates with ABAQUS and the experimental verification.Finally,numerical simulation program of the three-dimensional early age concrete pavement slab was developed,considering of paving time,size of slab and effecting of temperature and moisture.Under the coupling study of temperature and moisture on concrete pavement slab,the results show as follows.On the influence of temperature profile,slab during day and night is under the positive and negative temperature gradient,respectively.Hence,center and corner of slab uplift in turn.However,considering the effect of moisture,due to decreasing quickly on the top of slab moisture,slab forms a larger surface drying shrinkage.Considering coupling effect of temperature and moisture,slab corner uplift most of the time at early ages.The research of long-term mechanical behavior of the pavement slab shows that stress and displacement of the pavement slab increases gradually,when the stiffness of slab is promoting at the early ages.Then with the reason of creep and self-weight of concrete,the warp and stress of slab drop gradually.Moreover,the study found that the specific time point for variation of the warp and stress of slab changing is directly related to environmental conditions.The study of different size of pavement slab found that the stress and displacement of early age pavement increases with the increase of size,the increased tendency of the stress and displacement significantly weakened while the slab length surpasses 3m.It is illustrate that small size concrete pavement slab(less than 3m)can significantly reduce the deformation and stress of early age concrete.The size of pavement slab effect the deformation and stress of the early age pavement is not obvious when the size surpasses 3m.Research on the traits in early age slab shows that:characteristics of concrete slab in early age are closely related to the construction season and paving time in a day.Mainly due to the changes of the construction environment,the concrete slab will form different initial baseline characteristics and its traits will change with the experiences of different temperature and moisture profile.Comparison between computer program and field monitoring tests shows that:the improved computer program is able to simulate the actual changes of mechanical behaviors of concrete pavement slab in early-age period more precisely.The calculation accuracy of temperature and moisture field in pavement slab and the improvement of contact interface should be emphasized in the next step.