Numericalanalysis Of Multi-crack Cement Concrete Pavement And Its Overlay Structure

Cracking failure is one of the main forms of cement concrete pavement damage.When the cracks in the pavement structure reach a certain length,it will greatly affect the driving safety and reduce the driving comfort.If there are multiple cracks in the pavement structure,as the number of cracks increases,there may be certain interactions between cracks.The interaction between cracks may accelerate the expansion of cracks,thereby shortening the service life of the road.With the ABAQUS---a large finite element analysis software,this paper builds a three-dimensional model of the concrete concrete pavement with multiple initial cracks,obtain the stress intensity factor at the crack tip to analyze the interactions between cracks and the extension regularity of cracks.Furthermore,a 3d model of adding a layer to an old cement concrete pavement with several initial cracks is established.The overlay structure is rubber asphalt stress absorption layer and asphalt concrete surface layer.Through the model analysis,the influence of the modification measures to increase the asphalt overlay on the crack propagation is analyzed,so as to provide a basis for the structural safety assessment and reinforcement maintenance of the cement concrete pavement structure with multiple cracks.The specific content of this paper is as follows:Firstly,the three-dimensional finite element model of cement concrete pavement with single crack and two initial cracks is established when the vehicle is traveling at a uniform speed.Calculate the stress intensity factor value and J integral value of the crack tip By comparing and analyzing the calculation results of the cement concrete pavement structure with a single crack and two cracks to obtain the change law of the crack tip fracture parameters.The results show that there is an interaction between the cracks.At the same time,the influence of different structural parameters on the variation law of stress intensity factor of multi-crack tip was also discussed.Secondly,a three-dimensional model of a cement concrete pavement containing three initial cracks and four initial cracks when the vehicle is traveling at a uniform speed are established in order to analyze the effect of the number of cracks on the crack propagation law of the cement concrete pavement structure with multiple initial cracks.At the same time,the BP neural network was used to establish the prediction model of the stress intensity factor at the crack tip of the cement concrete pavement structure with initial cracks By statistically analyzing the crack tip stress intensity factor value of a cement concrete pavement structure with a single crack,two cracks,three cracks,and four cracks when the vehicle is traveling at a constant speed to predict the value of the stress intensity factor at the crack tip of a pavement structure with multiple cracks.Finally,a three-dimensional finite element model of a pavement structure with a rubber asphalt stress absorption layer between the overlay and the old cement concrete pavement with two initial cracks is established to calculate the stress intensity factor of the multi-crack tip on the pavement structure after the overlay.Then compare the calculated stress intensity factor value with the stress intensity factor value of the multi-crack tip before paving to study the effect of asphalt pavement overlay on the crack resistance of cement concrete pavement structure with multiple cracks.At the same time,this paper further explores the effect of different overlay structure parameters on its crack resistance.