Simulation of unbound material resilient modulus effects on mechanistic-empirical pavement designs: Fid-Bau Portal

Simulation of unbound material resilient modulus effects on mechanistic-empirical pavement designs

Xu, Qinwu / Ruiz, J. Mauricio / Moravec, Mike / Rasmussen, Robert O.

Abstract The variability of resilient modulus (MR) of unbound materials and subgrade due to laboratory test conditions affect pavement performance and designs. The performance-based mechanistic-empirical pavement design guide (MEPDG) is gaining more popularity in recent years for pavement design use. However, limited research efforts have quantitatively studied MR effects based on ME models. This research targets to evaluate the influences of MR variability on pavement performance and designs based on the MEPDG performance models. With a normal-distribution of MR seed values, pavement responses were computed with a layer-elastic analysis model, pavement performance was then predicted using MEPDG models, and design variability was studied via Monte Carlo simulation. Results indicate that the relationship between layer design thickness and MR varies from almost linear to nonlinear, which is highly dependent on the pavement structure and material properties. For the evaluated specific pavement structure and range of MR values, the least susceptible is the HMA design thickness as a function of MR under fatigue with a design Coefficient of Variance (CV) of 7.51 %, while the most susceptible is the base design thickness as a function of MR also under fatigue with a CV of 54.32 %. The combined effect of both rut depth and fatigue life considering the variability of both base and subgrade results in a design CV of 22.58 % for asphalt layer and 26.08 % for base layer. When using a weaker base layer or a thinner HMA layer, the modeled thickness design CV has changed −4.19 to 1.14 %.