Study On Failure Mechanism And Remediation Technology Of Asphalt Pavement Under Extreme Climate

Global climate warming is the background of all kinds frequent extreme weather climate events. Extreme weather event directly increase the damage and disease of pavement structure, reduce its service performance and service life, the economic efficiency and social efficiency suffer serious loss. This paper based on the southern area extreme low temperature climate (include freezing rain and ice disaster), northern area extreme high temperature and summer flood climate for research background, taking expressway asphalt pavement as the research object, synthesize methods of site investigation, laboratory test, numerical simulation and theoretical analysis, the failure mechanism and remediation technology of high-grade highway asphalt pavement which under various extreme climate conditions were systematically studied.The main achievements of the paper are as follows:(1) Aiming at the specific environment which is acting on highway engineering, the definition and action sphere of three extreme weather and climate events have been given, that is southern area extreme low temperature (include dreezing rain and ice disaster), northern area extreme high temperature and summer flood. The difference between each extreme climate and normal climate, and its typical failures and exprerssive characteristics to asphalt pavement structure and road transportation were obtained.(2) By means of site investigation, laboratory test and numerical simulation,the typical diseases and cause of south asphalt pavement which suffer extreme low temperature climate have been illustrated. The porosity, low-temperature bending strain, bending stifffness modulus and water stability of AH-70, SBS and CMA mixtures under different frost and thaw condition were obtained. The attenuation law of low-temperature crack resistance and freeze-thaw stability of each material were obtained. The pavement ice expansion model which concerned crack regional water in pavement structure has been built, and the mechanical response characteriatics of asphalt pavement local ice inflation under frozen action have been analyzed. (3) The typical damage features of north asphalt pavement which suffer extreme high temperature climate have been summarized. The rut factor, creep stiffness, dynamic stability and shear parameter of base asphalt, SBS and CMA binders and mixtures were obtained. Based on the temperature distribution of asphalt pavement under each extreme high temperature, the relationship between perment deformation and shear stress of structure layers which under different pavement structure and extreme temperature condition has been estabilished. The failure mechanism of north asphalt pavement which under heavy load and high temperature was put forward.(4) The typical breakage form and interlayer connection situation of north asphalt pavement which suffer summer flooding climate have been investigated and analyzed. The attenuation discipline of strength and water stability of each layer which suffered water immersion were obtained. The dynamic response model of pavement structure which under moving load was estabilished, and the pore water pressure of different pavement structure which under water-force coupling condition have been calculated. The disaster-causing mechanism of structural rutting of asphalt pavement in north region after was obtained.(5) Based on the present disease treatment scheme evaluation of asphalt pavement, the basic properties of repair material which appropriate each extreme weather condition have been analyzed. The suitable repair measures and optimum repairing time of typical diseases have been proposed, the construction technology of crack sealing and pothole repair were epurated. The best preventive maintenance time of asphalt pavement before extreme climate disaster has been determined by life cycle cost method.The research results can provide theoretical basis and data support to improve the effectiveness and reliability of pavement structure design, it also can alleviate pavement diseases, reduce the maintenance and repair costs. Furthmore, it has important reference value to revise and perfect the current design, construction and maintenance specification of pavement structure and material.