Numerical Simulation Analysis Of Anti-reflection Ability Of Road Structure And Material

Reflection crack is a common disease problem in the road structure,it mainly happens on the road at the grass-roots level,and on the base of road structure,cushion layer and surface extension,in the road structure through crack and eventually lead to its damage,its production is the main cause of road base and surface of the material strength and structure of set unreasonable,in extreme temperature and load conditions,The probability of reflection cracks in the road will greatly increase,greatly reduces the driving comfort,and serious cases will threat to road safety,in order to completely solve the problem,must on the cracking of the reflection and extension mechanism are analyzed,and based on this road material and structure of antireflective capacity study.A lot of preliminary investigation,literature review and data analysis on the reflection crack problem of semi-rigid base road are carried out.Based on the existing mechanism of road reflection cracks,this paper makes a deep theoretical analysis and thinks that the main reason of reflection cracks is that the semi-rigid base material with hydraulic rigidity shrinks and cracks under the action of temperature and water.The development of reflection cracks is mainly divided into temperature cracks and load cracks according to their causes.The expansion of load reflection cracks is mainly related to the bending and tension action and shear action in the type Ⅰ and Ⅱ cracking modes,while the temperature reflection cracks are only related to the bending and tension action in the type ⅰ cracking mode.On the basis of clear theoretical analysis of reflective cracks,the technical analysis of anti-reflective ability of typical road engineering materials and typical road engineering structures is carried out by numerical simulation.The finite element microscopic models of six typical road surface materials and four typical road base materials were established.The displacement and mechanical responses of these materials with and without cracks were studied by means of mid-span loading method,and the most suitable materials for anti-reflection crack structure were judged.The results showed that both in the road surface or at the grass-roots level,when cracks,stress and strain field of the material will have obvious change,the biggest concentration in the crack tip part,internal force and displacement in the surface material,the material’s ability to resist reflection with the percentage of coarse aggregate is enhanced by the rising,the SMA materials of antireflective ability significantly stronger than AC materials;However,among the base materials,the antireflection ability of macadam is much stronger than that of stabilized soil structure,mainly because the higher modulus of macadam can dissipate the stress and strain of cracks.Based on the existing road design specifications,typical road structure schemes are selected,and five kinds of structures representing secondary roads,expressways and long-life roads are selected respectively.The finite element models of five kinds of road structures were established by extended finite element method（XFEM）,and the anti-reflection ability of various road structures was analyzed by setting strip cracks at the bottom of the road structure base to simulate the cracking of the base.The results show that the tensile strain at the bottom of the surface layer increases obviously after the crack appears in the base layer,and the stress concentration phenomenon appears at the crack tip,which accelerates the crack expansion and leads to the deterioration of the road structure performance.The anti-reflection ability of the two kinds of long-life pavement structures is obviously stronger than that of expressway and secondary highway,which provides guidance for the design of anti-reflection crack pavement structures.