Mechanism And Control Methods Of Water Damage Of Asphalt Pavement

At present a lot of highway pavement condition investigation and experience home and abroad show that the free water which penetrates into the road structure is the major cause that induces or accelerates the road damages. On the basis of refering to domestic and foreign research documents, through theoretical analysis, experimental study and numerical simulation, effect of various environmental factors to water damage, the relationship between ultrasonic wave, permeability coefficient and injury tolerance are discussed, the design of road constructure and drainage method in the rainy condition are studied. The research work followed is carried out:(1) Test the water damage of asphalt road surface materials through the Hamburg rutting test, penetration test, ultrasonic test and uniaxial compression test. According to the test data, the model which contains the dynamic modulus, ultrasonic wave, the permeability coefficient and the injury tolerance is established, its development tendency and cause are analyzed.(2) The damage and defects of the asphalt mixture in actual use are simulated through methods such as setting different temperature, laying rubber blanket under the specimens, compressing the specimens in advance. The effects of rolling times, temperature and injury tolerance in soaking conditions on strength of materials, smooth and permeable coefficient of asphalt are discussed.(3) On the basis of unsaturated seepage flow theory, unsaturated seepage numerical simulation of highway structure is made using SEEP/W finite element analysis software. The infiltration laws in and after the raint condition are observed, through the relationship curve between the volume and moisture content, we find that bacause lacking of effective internal drainage Settings, the water in close-grained road structure layer can not be drained in time; and because transverse drainage path is too long, the edge drainage system drains ineffective; but the dewatering base layer combined with edge drainage system can drain quickly. Evaluating the effect of various drainage system, water table, embankment height, rainfall and cracks to the drainage performance.This work was supported by the Chinese Natural Science Foundations (Nos.51078222, 50708056 and 50978207) and Independent Innovation Foundation of Shandong University, IIFSDU (No.2010JQ001).