Numericalanalysis And Fatigue Life Study Of Cracks In Cement Concrete Pavement

With the increasing investment in infrastructure in China,cement concrete pavement as the main form of pavement is widely used.As the traffic tends to be overloaded,cracks on the cement concrete pavement will accelerate the destruction of the pavement slab.Study on the crack of cement concrete pavement in China are mainly concentrated in the crack causes and remedial measures for the study of crack propagation and the effect on fatigue life is not deep enough,and did not consider the temperature load effect on the crack growth of cracks.Therefore,it is necessary to study the crack propagation of cement concrete pavement under the coupling action of temperature and load.A three-dimensional numerical model of cement concrete pavement structure is established based on ABAQUS finite element analysis platform.Respectively study the crack length,load,temperature and load coupling effect and overweight effect of axial load on crack propagation,but also do the corresponding sensitivity analysis on Influence Factors of crack propagation and fatigue life.It provides a reasonable basis for cracking resistance design and fatigue life prediction of cement concrete pavement.The main contents and conclusions of this paper are as follows:1.Based on the basic theory of fracture mechanics,the mechanism of crack propagation and the critical failure mode are discussed;the temperature effect is introduced into the study of crack analysis,and the user subroutine of solar radiation,air temperature and convective heat exchange is applied to ensure the authenticity and reliability of the calculation results.2.In view of six different working conditions of temperature and load,nine kinds of different crack length and six kinds of overloading action are considered in each working condition,and three dimensional model of pavement structure is established respectively,taking the stress intensity factor as the evaluation index,and the analysis results of six kinds of working conditions are compared,and the law of crack propagation is studied.It can be found that the crack propagation tendency is more positive than the positive load under the eccentric load.The coupling action of temperature and load intensifies the crack propagation,and the low temperature condition is more serious.At the high temperature in summer,the crack has no open type expansion trend.The effect of overloading greatly accelerates the cracking of cracks.3.The equivalent stress intensity factors obtained under different working conditions are calculated,and the curve fitting is carried out.The fatigue life of pavement slabs is obtained by integrating the Paris formula.It can be found that the fatigue life of pavement slabs decreases with the crack propagation,and the fatigue life under the action of partial load is slightly larger.The coupling effect of temperature and overweight load makes the fatigue life sharply reduced,which should be avoided in practice.4.Sensitivity analysis was carried out by influencing factors such as thickness and modulus of the facing layer.It can be found that increasing the thickness of the surface layer,the modulus of the base layer and the thickness and modulus of the subbase can effectively slow down the cracking and increase the fatigue life of the cement concrete;Among them,the increase of surface layer thickness is the most significant to improve the fatigue life,while the change of soil parameters has no influence on the fatigue life.