The Research On Water Damage Mechanism Of Semi-rigid Base Asphalt Pavement And The Fatigue Performance Of Its Structural Sheaf

Semi-rigid asphalt pavement is the main form of highway pavement structure in our country, although we have made a deep research on semi-rigid asphalt pavement, but its features haven’t been fully understood, this lead a direct result that highway pavement early damage issues of semi-rigid asphalt pavement highlighted,under this research background, the thesis expanded research on damage problems of semi-rigid base asphalt pavement.Through the full investigation in damage problems along the highway semi-rigid asphalt pavement, we use pavement flatness, rutting and pavement structural strength detection methods to analysis the water distress condition and its causes of a highway according to relevant regulations; thus analysis the causes of water damage and make a assessment on the semi -rigid base asphalt pavement,the results show that the standard asphalt mixture density of the water damaged asphalt core samples is low and the residual porosity of the asphalt pavement is larger than normal,which is prone to water leakage,resulting in water damage to asphalt pavement; flexural-tensile strain at the bottom of the asphalt layer under load flexural tensile cracked first, and then gradually extended upward,which becoming a source of water damage; The surface of asphalt mixture and water stable macadam mixture has a thick mixture of mud layer which softened by water, making the adhesion between cementing material and stone gradually lose and then lead to loose occur, resulting in water damage to asphalt pavement is mainly embodied in the form of pot holes, loose and slurry pump; The water damage is divided into the following types: The surface layer of water damage from top to bottom and destroy the whole structure of watersurface layer water from the bottom to the top, it is a destructive phenomenon due to the loss of adhesion between asphalt and aggregate,so it will not only lead to loose road surface damage, but also reducing road durability and may induced other damage problems, and even lead to the rapid destruction of the integrity of the pavement structure, which is very dangerous; On the basis of the formation mechanism of the typical semi-rigid structural fatigue cracks in asphalt pavement, according to two typical computational scheme design of the asphalt pavement, the mechanism of the mechanical response of pavement structure was revealed,The results show that tensile stress of the semi-rigid layer under the interlayer sliding state was bigger than tensile stress in the same position under the layer of a continuous state, which indicating that the increasing thickness of the pavement structure helps for lowering levels of internal tensile stress significantly.On the basis of the formation mechanism of the typical semi-rigid structural fatigue cracks in asphalt pavement, according to two typical computational scheme design of the asphalt pavement, the mechanism of the mechanical response of pavement structure was revealed,The results show that tensile stress of the semi-rigid layer under the interlayer sliding state was bigger than tensile stress in the same position under the layer of a continuous state, which indicating that the increasing thickness of the pavement structure helps for lowering levels of internal tensile stress significantly.The thesis proposes preventive measures to prevent early damage to the asphalt pavement, which has important practical significance,and can be a reference for similar projects.