Study On Dynamic Response Of CRC+AC Composite Pavement Under Moving Load

Composite pavement of rigid and flexible is composed of two layers of different material types and mechanical properties, Composite asphalt pavement of continuously reinforced concrete (CRC+AC) is a new composite pavement structure that combines high-intensity of CRC with flexible of AC, Compared with continuous reinforced concrete pavement (CRCP), It not only has high intensity, good durability, also has comfort driving, long service life, small maintenance cost and other benefits, from the long term performance, it is one of the development directions of the Long Life Asphalt Pavement structure for the heavy load traffic expressway with good economy.A three-dimensional numerical model for cracked CRC + AC was presented by using finite element software ABAQUS in this paper, at present the study on the pavement structure mechanical response is mostly based on the premise of static load of vehicle, which is quite different from the force condition of actual roads. User subroutine Vdload is used to simulate uniform motion of the vehicle; and user subroutines Dload and Utractload were used to simulate brake model. Based on the analysis of composite pavement structure under different condition, the main conclusions are the following:After compared with static loads, we can see the influence scope of uniform motion is greater in vertical displacement; the maximum of steel stress and shear stress in the pavement structure is less than the corresponding value under static load, after the depth analysis of the dynamic response of moving loads of the composite pavement, you can see the deflection of the pavement is mainly resulted from subgrade; CRC+AC surface course of pavement is mainly in the three dimension compressive stress; the maximum horizontal tensile stress and transverse tensile stress were located in the joint of CRC and the subbase course; Compared with CRCP, The AC layer provides some protection for CRCP, and can reduce the dynamic response of pavement structure under moving load.A brake model is built to simulate intersection or charging stations which have lots of braking in chapter 4. After compared with uniform load, with the increasing of horizontal loads, dynamic response index of pavement structure have increased, which deflection and the vertical stress were affected relatively small, but the brake loading have a remarkable effect on the horizontal stress, the horizontal shearing stress and steel stress. At the same time, with the increase of depth, the effect of brake load will gradually weaken, the main influence area concentrated in the AC layer and CRC layer.Analyzed pavement deflection, steel stress, the horizontal shearing stress, the horizontal tensile stress of CRC and subbase course by changing the influence factors which influence composite pavement. It is concluded that the reinforcement arrangement of "small diameter, small spacing" can better play the mechanical properties of the pavement structure in the same ratio of reinforcement; with the increase of crack width, mechanical indexes will increase, which steel stress most affected; the selected mechanical indexes and load are basically linear relationship, for pavement structure, there is an optimal AC thickness, the function of AC will decrease and the horizontal tensile stress will increase when AC layer become too thick; the subbase modulus have little influence on pavement deflection, with the increase of the subbase modulus, the maximum horizontal tensile stress of subbase will increase; while the subgrade modulus play an important role in pavement deflection, and with the increase of the subgrade modulus, the maximum horizontal tensile stress of subbase will decrease; the vehicle speed have a remarkable effect on the dynamic response of CRC+AC, there is a critical speed, which is 60km/h to 100km/h in this paper, effect tendency is different at two sides.