Study On Mechanical Response And Drainage Characteristics Of OGFC Pavement Based On Spatial Variability

With increasing occurrence frequency of city-type floods,Open Graded Friction Course(OGFC)with drainage function has draw much attention.Road designers generally consider pavement materials are uniform when designing OGFC pavement.In fact,due to the complexity of material structure and compaction,there is non-uniformity in surface layer materials and base layer materials of asphalt pavement.The ununiformity has influence on mechanical response of pavement under the load of vehicles.Besides,drainage is one of the most important functions of OGFC pavement,and drainage characteristics are significant for studying OGFC seepage and evaluating drainage performance of OGFC pavement,but a lack of studies lay on drainage characteristics of OGFC.Based on random field theory,3D finite element models are developed for considering spatial variability.Statistical methods are used to analyse mechanical response and drainage characteristics of OGFC pavement.The main work includes the following two aspects:(1)Analyse the influence of spatial variability on mechanical response of OGFC pavement.A computer program was written to simulate the spatial variability of material modulus,and the random data was imported into a 3D finite element model of the pavement structure for calculating the mechanical response of pavement.A comprehensive analysis is made for studying the effect of random field digital characteristics(mean,coefficient of variation,correlation distance)on mechanical response of pavement.The results describe: the mean and standard deviation of strain at the bottom of surface layers,strain at the top of roadbeds,deflection of road surfaces both reduce with the increase of mean modulus of surface layers and mean modulus of base layers;the mean and standard deviation of stress at the bottom of base layers reduce with the increase of mean modulus of surface layers,but raise with the increase of mean modulus of base layers;the mean and standard deviation of strain at the bottom of surface layers raise with the increase of coefficient of variation(COV)of surface modulus and COV of base modulus;the standard deviation of strain at the bottom of surface layers increases as correlation distance of surface modulus and correlation distance of base modulus getting larger.(2)Study drainage characteristics of OGFC.A 3D finite element model is developed to simulate the rainfall infiltration and drainage process of OGFC.A study is carried to clarify the effect of cross-anisotropy of permeability parameter on OGFC rainfall infiltration and drainage process.An analysis is made for studying the influence of spatial variability of permeability coefficient on the drainage performance of OGFC.The results present: thedrainage capacity of OGFC improves with the increase of cross-anisotropy coefficient of permeability parameter;the drainage performance of OGFC raises with the increase of mean of permeability coefficient,but reduces with the increases of COV.The results of this study clarify the impact of spatial variability on mechanical response and drainage performance of OGFC pavement,and it’s significant for improving the mechanical analysis method of asphalt pavement and evaluating the drainage performance of OGFC.