Research On Moisture Transfer Characteristics Of Excavation Section Of Expressway And Subgrade Resilient Modulus Prediction

The subgrade is the basis of pavement structure whose intensity, stiffness, stability andservice performance are determined by its resistance to deformation. The performance ofsubgrade is remarkably affected by the factors of hydrogeology, earthiness, soil dry densityand so on, in which moisture migration is a key factor in the effect to the performance ofwhole pavement structure.The most of previous studies related to the moisture migration are based on fillembankment, rarely on excavation cutting. Base on this, the moisture migration characteristicsof excavation section was studied by the way of field measurement, laboratory test, numericalsimulation and so on in this paper, in the selected section of expressway of Zhang Jia-kou toZhuo Zhou, He Bei Province. The resilience modulu prediction model was deduced by thefield test data. Meanwhile, the law of whole resilience modulus which has been covered bythe pavement was analyzed and concluded based on temperature field simulation, thus themost advantageous and the most adverse construction time was established in this area;Finally, the correction coefficient of resilience modulus model which had considered theinfluence of pavement was put forward.The relationship between resistivity and moisture content had been obtained by thecalibration lab test by tracking measurement the resistivity and temperature on differentdepths in the choosen test sections with different excavation depth; Based on therelationship，a series of engineering measures were put forward.The law of subgrade temperature variation had been obtained based on the temperaturefield model which with different excavation depth, and the association between moisturetransfer and temperature field mode had been further analyzed; The parameters oftemperature field model had been fixed and the subgrade temperature with differentpavement construction time had been analyzed.The trend of the subgrade resilient modulu had been got though the moisture transfer lawand characteristics; The effectiveness of engineering measures had been proved by contrastingthe different of resilient modulus before and after using engineering measures and thestrength and stability of subgrade had been improved because of inhibiting the moisturetransfer; The numerical relations between temperature and moisture content was establishdand the rule of subgrade moisture transfer after pavement construction had been forecasted;The resilient modulus trend for pavement construction, and the correction coefficient forsubgrade resilient modulus had been obtained considering the change of subgrade resilientmodulus with different pavement construction time.