Research On Mechanical Analysis For Beijing-tianjing-tangshan Expressway Based On Old Road With Three Dimensional Horizontal Crack

Beijing-tianjing-tangshan expressway was open to traffic at the end of eighties. The transportation artery drove economic construction of beijing,tianjing and tanggu area. With more than ten years of running, its traffice increased every year by the rate of 20%, so traffic volume gradually reached a saturation value and pavement performance and service degree seriously degraded, which couldn't meet the need of the develop of social and economy, upgrading and expansion is imperative.Highway upgrading design firstly must survey the performance-weakening condition of present pavement to obtain pavement basis designing parameters. The paper detected load-carrying ability of typical section, carried on performance tests over cored boring samples sectionally and made scientific evaluation for pavement performance of each section. On the base of which the paper designed overlay for different sections mainly according to the whole using condition of beijing-tianjing-tangshan expressway and pavement damage characteristics of different sections. So the technic support for the upgradation of the road was provided.With beijing-tianjing-tangshan upgrading projects depended on, local climatic condition and damage condition of old road were surveyed and analysed, which showed that crack and rut were still the main damages for each section. In order to make the overlay designing more adopt to present old road condition, the paper built a overlay mechanical model with old road bearing three dimensional crack and added pavement temperature field in the model by large finite element software ANSYS10.0,deeply studied overlay mechanical law under load model,temperature model and coupling modes of load and temperature, analyzed the sensitivety of pavement parameters,environmental condition and loading mode towards the mechanical response of overlay, so the influence old road crack had on the force distribution of overlay under different loading modes was revealed, which could reflect the reasons for the generation of reflection crack to some extent. By theoretical calculation and comprehensive analysis, the paper put forward overlay designing method for beijing-tianjing-tangshan expressway based on damaged old road. What's more, the paper also recommended typical pavement structure for beijing-tianjing-tangshan expressway upgrading projects.