Study On The Influence Of Base Surface Interface Morphology On The Mechanical Properties Of Asphalt Pavement

The current theory of pavement design assumes a complete continuous contact between the various structural layers of the asphalt pavement and ignores the thickness of the contact interface between the layers.However,in engineering practice,the contact interface between the structural layers of the pavement does exist,and the interface morphology is also varied due to factors such as materials or construction.The interface has a complex spatial structure that affects the embedding force and bonding force between the two layers of material.In order to effectively reduce the occurrence of slippage and reflection cracks in the asphalt pavement,it is necessary to study the relationship between the interface between the base and the surface and the cracking fatigue of the asphalt pavement.The research object of this paper is semi-rigid base asphalt concrete pavement,starting from the interfacial interface morphology between semi-rigid base layer and asphalt surface layer,using fractal theory and three-dimensional imaging technology,semi-rigid base layer and asphalt.The three-dimensional reconstruction of the interfacial interface between the surface layers is carried out,and the calculated fractal dimension is used as an index for the description of the interface between the base and the surface layer.Based on this,the influence of interfacial interface morphology on the mechanical properties of asphalt pavement is studied.The specific research contents are as follows:(1)Using the three-dimensional imaging technology and the fractal theory of application,the interface between the base and the surface layer is treated,and three different interface modes of the base-surface layer are obtained.Three dimensional reconstruction of the interface between the base and the surface of semi rigid base asphalt pavement is carried out.Then,using the fractal theory and MATLAB software,the fractal dimension of three different interface forms between the base and the surface is calculated by the improved cube covering method,and the fractal dimension is used to characterize the interface form between the base and the surface of the asphalt pavement.(2)The semi-rigid base asphalt pavement structure is formed into test pieces of various sizes,and the shear test,the pull test,the split test,and the three-point bending test are respectively performed,and the base-surface interface of the asphalt pavement is combined and characterized.The fractal dimension of the morphology explores the influence of the interface morphology on the mechanical strength between the layers.(3)A two-dimensional discrete element model is generated for the cross-section of the trabecular specimen of a semi-rigid base asphalt pavement by means of digital image processing technology.In order to avoid the influence of aggregate size,shape,position and micro-parameter parameters on the stress state of the model,in order to better analyze the influence of inter-layer interface morphology on the inter-layer stress response,the base-surface layer of the two-dimensional discrete element model is used.The interface morphology is randomly divided into five types,and other parameters remain unchanged,and the fractal dimensions of the five interface forms are obtained.Then,the load and constraint are applied to the discrete element model,and the stress response of the model under different interface modes is obtained.The relationship between the interface morphology and the interlaminar stress response of the asphalt pavement base-surface layer is established.(4)The three-point bending fatigue test of semi-rigid base asphalt pavement was carried out to study the relationship between interlayer interface morphology and fatigue life.Then,the two-dimensional discrete element model is used to simulate the three-point bending test to study the relationship between the interface morphology and pavement cracking.Then,three-point bending fatigue tests with stress levels of 0.4,0.5 and 0.6 were carried out on the first interface model,and the virtual results were compared with the laboratory tests.The results show that the three-point bending fatigue test can well simulate the fatigue process of asphalt pavement with semi-rigid base and the generation and propagation of cracks,and truly reflect the fatigue test results,which shows the rationality and feasibility of the virtual test.Finally,the three-point bending fatigue virtual test was carried out on five models with different Base-Surface interface morphology,and the effect of Base-Surface interface morphology on fatigue life was analyzed.The fatigue cracking mechanism of semi-rigid base asphalt pavement was revealed from the microscopic point of view.(5)Based on the laboratory fatigue test,the fractal dimension,which represents the interface morphology between base and surface,is firstly used as the influencing factor of fatigue life,and the fatigue prediction model of semi-rigid base asphalt pavement is established considering the stress,temperature and age.