A mechanistic approach was applied in a study of stability of open-graded drainage layers where there is substantial truck traffic. In the research, three drainage test sections were constructed on a segment of I-469 in northeastern Indiana, USA. The drainage system components include an asphalt bound open-graded (OG) drainage layer underlain by dense filer layer, trench/pipe collector system and outlet. The OG drainage layer thickness varies and the filter layer includes combinations of dense asphalt bound and dense unbound aggregate bases. In the study, laboratory triaxial tests were conducted on all asphalt mixtures, unbound aggregate materials and subgrades. As a result, modulus and shear strength was determined for all materials. Field pavement response was obtained from Falling Weight Deflectometer (FWD) tests. Finite element analyses (FEA) with the laboratory determined material properties were used to validate pavement response to the FWD loads, examine layer shear stability in terms of shear stress and strength and compare predicted and measured rutting. (a)
Abstract