Mechanical Response And Damage Analysis Of Typical Pavement Structure Under Different Interlayer Bonding States

For a long time,how to reduce the diseases of all kinds of pavement structure and improve its service life has been concerned;as two typical pavement structures,cement concrete pavement and asphalt pavement,have been widely used.However,due to the layered paving,layered rolling and block paving of each structural layer of pavement,and the influence of climate conditions and the difference of materials of each structural layer,it is easy to cause the interface between layers not to bond tightly,which is difficult to achieve the ideal state of interface bonding.As a result,the asphalt pavement appears cracks,swelling and cement concrete pavement appear breaking boards,wrong unit and other diseases.Based on this,this paper will take the cement concrete pavement structure and inverted asphalt pavement structure as the research object,analyze the influence of different interlayer bonding state on the mechanical response of the two pavement structures and the damage rule,in order to provide theoretical support for improving the service life of pavement structure.The main results are as follows:(1)The results show that the order of the influence of different interlayer bonding states on the surface deflection,tensile strain at the bottom of asphalt mixture layer,tensile stress at the bottom of inorganic binder layer and vertical compressive strain at the top of subgrade is as follows: fully slipping interfaces between surface layers > fully slipping interface between middle and lower layers > fully slipping interface between upper and middle layer;the influence of interlayer bonding states on the spatial distribution of mechanical responses of asphalt pavement is small.When the inverted asphalt pavement and semi-rigid base asphalt pavement are fully slip interface between the middle and lower layers,the tensile strain at the bottom of the asphalt mixture layer and the tensile stress at the bottom of the inorganic binder layer are the largest.Therefore,rutting and fatigue cracking are more likely to occur under the two working conditions of fully slipping interfaces between surface layers and fully slipping interface between middle and lower layers,and the bonding interface of the above two working conditions should be strengthened during construction and maintenance.(2)Fatigue cracking and permanent deformation damage of inverted asphalt pavement structure are the largest the condition of fully slipping between surfaces and layers;on the whole,the influence of different periods on the fatigue cracking and permanent deformation damage of asphalt pavement structure are the largest in summer and the smaller in winter.From the superposition of the two damage modes,the damage caused by the fully slipping interface between middle and lower layers is more than that of fully slipping interface between upper and middle layers.The total damage of fatigue cracking at the end of a year is more than that of permanent deformation under different bonding conditions,so the inverted asphalt pavement may be mainly affected by fatigue cracking.The results show that the total damage of fatigue cracking at the end of a year is more than that of permanent deformation under different bonding conditions,so the inverted asphalt pavement may be mainly affected by fatigue cracking.Therefore,more attention should be paid to the fatigue cracking of inverted asphalt pavement,and attention should be paid to the bonding of interface and overload limitation in summer.(3)The results show that the maximum stresses of the two slabs are increased by 52.35% and 37%respectively under the condition of full slipping between the base and surface layers of cement concrete pavement;the shear force of the dowel bar under the condition of full slipping between the base and surface layers is greater than that under the condition of full bonding between the base and surface layers of cement concrete pavement under the direct action of traffic load,and the opposite is true under the condition of no direct action of wheel load.When the base surface layer of cement concrete pavement changes from fully bonding to fully slipping,the stress of surface layer increases and the stress of base layer decreases;the vertical deformation resistance of cement concrete pavement is not affected by the interlayer bonding condition.(4)Under uniaxial load,the fatigue cracking index of cement concrete pavement with fully slipping between base and surface layers increases by 51.66% and the design life decreases by 3.8 years compared with that with full bonding between base and surface layers.Under multi axial load,the fatigue cracking index of cement concrete pavement under the condition of full slipping between the base and surface layers increases by 62.2% and the design life decreases by 2.77 years compared with that with full bonding between base and surface layers;under different interlayer bonding conditions,the order of contribution factors of the sum of multi axial load cracking index is uniaxial > biaxial > triaxial.Therefore,in the design and maintenance of cement concrete pavement,it is necessary to strengthen the bonding between the base and the surface layer,control the overload,increase the thickness of the surface slab and other methods to reduce the fatigue cracking of cement concrete pavement.