Structure Research Of Composite Long-life Pavement

Currently, the design time limit of highway is generally 20~30 years in our country, but actual service life only lasts 8~10 years, even some highway start appearing more serious damage after 2~3 years. For highway, the maintaining will bring inconvenience to customers, prolong travel time of customers, result in great waste about Maintain expenses and custome expenses, bring huge economy loss to the society in the meantime. In all the highway life span period, this is uneconomical obviously. How to prolong the usage life of highway, currently become one of the most important researches about highway in our country. This paper aims at the shortage of design life and actual life for highway, researches definition and standard about long-life pavement, analyses structure style of long-life pavement, slab division of cement concrete and the stress of structure etc.The research in this paper consists of some aspects as follows: (1) Through the reseach for the definition of long-life pavement in different countries, analyse the definition of long-life pavement, and the design requirement and standard of long-life pavement was given. At the same time, the structure style of long-life pavement for actual engineering was suggested. (2) Through the reseach about lane width, the safe drive speed of highway was gotten.The slab division of cement concrete was analyzed. In order to ensure the vehicle loads exsiting between two sides of cement concrete slab, and ensure the cement concrete slab in low stress condition, the 3m×4m slab division way was given. Through the analysis for load stress and temperature stress, the superiority of slab division way was reasearched. Combining the research of lane width, the design project for building six lanes in 28 meter basement was suggested. (3) This paper suggests the temperature condition about the area where the actual engineering exsits. The pavement temperature diagram about different typical season was given. Through the relevant theory about temperature field and temperature gradient, the maximum temperature gradient of composite long-life pavement was calculated. This provides the basis for the structure desigh and analysis. (4) Through specification way and finite element analysis, the factor that influences the curved stress of cement concrete was analyzed. This provides the theory basis for pavement design. (5) Through finite element analysis, the shear stress was calculated, and the position where maximum shear stress appens was gotten. At the same time, the influence to shear stress from the thickness of asphalt concrete was researched, and the suitable thickness of asphalt concrete about composite long-life pavement was given. (6) According to stress analysis and experiment, material design for each flexible layer of composite long-life pavement was reasearched, and the suitable mixture proportion design was give. At the same time, the standard about mixture design was suggested. (7) The influence to ideal life estimating of long-life pavement from some sensitive factor was analyzed. Through the life estimating way, the ideal life of composite long-life pavement was estimated. At the same time, the superiority of long-life pavement about the economy factor was contracted with asphalt concrete pavement and cement concrete pavement respectively. (8) In order to ensure that cement concrete pavement combines to asphalt concrete pavement closely, the surface baring technique about cement concrete was given, and baring time and baring depth requirement was suggested.