Method for optimizing double-layer pa pavement structure into three-layer structure based on equal permeation rate

A method for optimizing double-layer PA pavement structure into three-layer structure based on equal permeation rate, comprising the following steps:

• S1, studying a relationship between a pavement structure and a material composition segregation of different nominal maximum particle sizes and different paving thickness, determining a multiple relationship between paving thickness and nominal maximum particle size, and compressing the thickness of an upper layer and a lower layer of a double-layer PA pavement, and obtaining the thickness and the nominal maximum particle size of an added layer by combining a principle that the total thickness of the pavement before and after optimization is unchanged, so as to form an initial three-layer PA pavement;
• S2, studying the effect of air voids, paving thickness and nominal maximum particle size on a permeation rate, and establishing a prediction model of permeation rate based on an XGBoost algorithm;
• calculating the air voids of the upper layer and an intermediate layer of the initial three-layer PA pavement according to the permeation rate of the upper layer of the double-layer PA pavement before optimization, and completing an optimization design of the material composition of the upper layer and the intermediate layer;
• S3, studying the effect of different distribution amounts of emulsified asphalt between the intermediate layer and lower layer on the permeability of the lower layer and interlayer bonding capacity according to the feasibility of the actual construction process of the three-layer PA pavement, and based on the effect of different dosages of emulsified asphalt on an interlayer shear strength of the intermediate layer and lower layer and permeability of the lower layer, determining the dosage of emulsified asphalt between the intermediate layer and lower layer, and determining the amount of interlayer emulsified asphalt of the intermediate layer and lower layer;
• S4, studying a relationship between the air voids and the permeation rate of the lower layer PA pavement under a given amount of emulsified asphalt, based on the principle that the permeation rate of each layer of the three-layer PA pavement is equal, determining the air voids size of the lower layer, and determining the thickness and material composition of the final three-layer PA pavement.