Research On Structural Optimization And Measurement Of The Pore Pressure For Asphalt Pavement

The pore water pressure which washed asphalt mixture repeatedly could contribute to theseparation of asphalt and aggregate, expand the crevice, increase voidage of mixture and finallydecrease the entire strength of the asphalt pavement construction and then lead to various moisturedamage. Thus, it is crucial to investigate the pore pressure of asphalt pavement and present theoptimized design considering the influences of the pore pressure.Firstly, on the basis of the working principle of fiber Bragg grating (FBG) sensing, a sort of newnovel pressure sensors were designed and created. The sensors then were installed in the surface layer,the interface of surface layer and lower surface layer, and the interface of lower surface layer andstone base to measure the pore water pressure.Secondly, the actual porosity ratio of every specimen drilled from pavement is measured. A kindof test equipment system was invented to measure the hydraulic conductivity of specimens in thecondition of different pressures, and then the hydraulic conductivity of the specimens in differentconditions could be obtained. The relationships between the hydraulic conductivity and the waterpressure are also discussed along with the discussion of the relationship of the hydraulic conductivityand porosity ratio.Thirdly, on the basis of porous media and Biot theory and axial symmetry finite element analysismethods, depending on the practical parameters of pavement, the pore water pressure in asphaltpavement which is in water-saturated was simulated, calculated and analyzed by using of ABAQUSsoftware. Comparison of theoretic simulation values and measured values shows that both values areconsistent, and the feasibility of measurement of pore water pressure of asphalt pavement by fiberBragg grating (FBG) stress sensor is confirmed.Additionally, according to the sensibility analysis method, numerical simulation of water-saturated asphalt pavement is performed. The results indicate that the most important factor toinfluence the pore water pressure is the hydraulic conductivity of asphalt mixture, and the other fourfactors can be put in order as tire stress, velocity, modulus, and thickness according to the influencedegree from high to low.Finally, calculation and analysis of excess pore water pressure regarding to several typicalpavements are conducted, the hydraulic conductivity of surface layer is optimized, and then theoptimization design of the hydraulic conductivity of several typical pavements are confirmed.