Study On Formation Mechanism And Control Methods For Rutting Of Asphalt Pavement In Long And Steep Longitudinal Slope Sections

China is a mountainous and hilly country. Thus, with the continual extension of the highways to the mountain areas, the road designers will inevitably encounter the "long" and "steep" slope problem during the design process. But they didn't take the pavements, which have long and steep slopes, into special consideration during the existing road design, making road sections in such regions go through serious rut deformation in a relatively short period of time after the completion of the road sections.Combined with the collected rut disease data of a highway in Zhejiang province, the paper made a field survey about the rut disease of another two long and steep road sections in Shandong province, and analyzed the distributions of the longitudinal and transverse rut. Then the paper analyzed the factors of the rut disease, and suggested to study the Formation Mechanism of the Rut Disease by studying the climbing speed of multi-axial heavy capacity vehicles.By founding a finite element model, the paper studied the permanent deformation process of the long and steep asphalt pavements, and made a sensitivity analysis of the parameters C1, C2 and C3 of the creep model, which stimulated the rut deformation. Meanwhile, the paper studied the influences of the vehicle speed on the permanent deformation, stress and the creep strain along the road depth of the long and steep road sections.Associated with the founding of moving load model, the paper stimulated the climbing process of vehicles on the long and steep road sections. And the stimulation included the pre-accelerated state before going uphill, and the constant state of driving after slowing down to the ideal state when the slopes were long enough. According to the stimulation, the paper analyzed the distributions of the vertical displacement, the maximum shear stress and compressive stress along different directions under different road conditions, and analyzed the influences of the vehicle speed and the horizontal force coefficients on roads under moving load.Finally, combined with relevant researches and theoretical analysis, the paper defined the long and longitudinal grade rut based on the rut of asphalt pavements. And in the light of the characteristics of rut disease in the special long and steep road sections, the paper put forward an optimization design proposals based on controlling the mid-surface course, and proposed a series of relevant non-structural prevention measures.