The Research On Rigid-Flexible Continuously Reinforced Concrete Composite Asphalt Pavement

Composite asphalt pavement of continuously reinforced concrete (CRC+AC) is a new composite pavement structure that combines high-intensity of CRC with comfort driving of AC; As a rigid foundation, CRC plays the major role of a load-bearing , AC surface layer plays the major role of function. With its overall high intensity, long service life and small maintenance cost, it is one of the development directions of the long-lived asphalt pavement structure for the heavy load traffic expressway.This paper relies on the technology of the overhaul engineering of the first grade highway such as Changtan expressway, Changyong expressway and the 325 national highway of Guangdong Enping. According to the CRC+AC structural features and on the design theory and method of CRC+AC, this paper carries out the research of load stress, temperature stress, end displacement and structure, tension bars of longitudinal joints stress analysis and design as shoulder slab unreinforced, analysing interlaminar shear stress, shear strength testing of interlaminar materials, structural design of CRC+AC, reinforcement design and construction technique, materials performance and entitative engineering application and then form a more effective research results.According to the CRC+AC structural features, this paper forms the structure system theory of CRC+AC, analyzes the damage model CRC+AC structure, proposes three major damage forms of interlaminar interface sliding and lapse, CRC slab edge thrust destruction and reinforced abruption damage, etc. Interlaminar sliding needs to be controlled by AC layer thickness design and interlaminar structure and materials design. CRC slab edge thrust damage could be controlled through the design of slab thickness and reinforcement. Reinforced abruption damage meet the concrete volume shrinkage stress primarily through reinforcement design.Applied the space isoparametric element finite element model, this paper analyzes the load stress and temperature stress of CRC+AC structure. This analysis is about the influence rule of unfavorable load position and all other parameters of the structure to CRC slab stress, obtains the two critical load positions of CRC slab as the different crack spacing L_d appeared in such slab and points out that the stress states of CRC structure get to the best at the best crack spacing of L_d =1.5～2.0m. To facilitate structural design, this paper analyzes the CRC slab stress without AC surface layer, draws nomograph, regresses calculation formula and proposes the correction coefficient K_d of foundation modulus E_t.To the assumption and practice of shoulder edge slab unreinforced, this paper analyzes the end displacement of CRC slab when edge slab is reinforced or unreinforced and then verifies it with finite element method, and analyzes the calculation of the sliding area length L₁ in the constraint condition of shoulder edge slab tension bars of longitudinal joints. According to end displacement situation of CRC+AC structure and engineering practice, in view of the difference to CRCP, this paper proposes the end disposal method of bridge expansion joints and the way combined with bridge structure expansion device, as well as corresponding structure form. This paper proposes the AC layer thickness design model considered of interlaminar shear index based on the CRC+AC structure interlaminar interface shear stress analysis and test of interlaminar bonding layer materials shear strength. This paper also considers the interlaminar interface shear stress, bond layer materials shear strength, determination ways of AC layer thickness under the rutting permitted depth and the requirement of interlaminar interface structure form and materials.According to the critical load position and load combination of CRC+AC, in the basis of current codes JTG D40-2002, taking the slab-bottom integrated fatigue stress for index, this paper proposes the CRC thickness design methods. The content is to propose the load combination I consisted of the middle of transverse joint edge load stress and transverse thermal curling stress of corresponding position as the most unfavorable load model to control the CRC slab edge thrust damage, and proposes the checking method of CRC slab edge thrust damage in the condition of the extreme crack spacing.Based on the reinforcement design of CRC slab in the JTG D40-2002, the best crack spacing (1.5m～2.0m) and the appropriate crack width (0.7mm～1.0mm) is analyzed. Selection principles, layout and requirements of longitudinal reinforcement diameter and spacing are proposed. The plane size of CRC slab, the setting of joint and tension bars of longitudinal joints design as shoulder edge slab unreinforced is also proposed.Through the construction of CRC+AC and CRCP test road, the actual investigation of the CRC+AC road performance, and the accumulation of CRC+AC pavement design and construction of experience, a number of key technical issues in construction is successfully solved, including reinforcement fabrication, installation and stent, concrete mix design and index, double amount of concrete materials swelling properties control, construction burden distribution and vibrating control, end disposal construction, etc. The test road is observed and the situation of cracks changes of CRC slab of test road is surveyed.