Prediction of Deterioration of Asphalt Pavements by MechanisticEmpirical
Prediction of Deterioration of Asphalt Pavements by Mechanistic-Empirical Methods Eugene OBrien • University College Dublin • Professor of Civil Engineering • Eugene. OBrien@ucd. ie • Portorož, Slovenia
Trucks bounce & rock; axles hop. . Portorož, Slovenia
Impact Factor Spatial Repeatability – same truck on same stretch of road Distance (m) Portorož, Slovenia
Spatial Repeatability can be detected with multiple-sensor WIM Portorož, Slovenia
Impact Factor Lack of Spatial Repeatability for ‘similar’ trucks Distance (m) Portorož, Slovenia
Impact Factor ‘Statistical’ Spatial Repeatability (France) Distance (m) Portorož, Slovenia
Dynamic Force ‘Statistical’ Spatial Repeatability (Netherlands) Distance (m) Portorož, Slovenia
Implications for Road Damage • Traditionally assumed that impact force was applied at random locations along pavement • In fact, certain locations will repeatedly attract high impact loading • This damages & changes the road profile • New road profile changes pattern of Spatial Repeatability • Feeds on itself: Road profile influences truck dynamics spatial repeatability pattern change in profile change in spatial repeatability pattern . . . Portorož, Slovenia
Computer model to represent truck dynamics Elevation (m) Quarter Car Model used to represent entire truck fleet IM sor W n e S 16 y Arra Tr an sv e rs e. D ist an ce (m ) 09 tance s i D l na di tu Longi Portorož, Slovenia (m)
Probabilistic Quarter-Car Model Portorož, Slovenia
Optimisation to find Quarter-Car Properties Find μi & σi which minimise Σ(SSRmeas – SSRtheory)2 Portorož, Slovenia
Dynamic Force Predicting Statistical Spatial Repeatability Distance (m) Knowing μi & σi, we can predict patterns of SSR for any profile Portorož, Slovenia
Road Damage Model – Collop & Cebon Portorož, Slovenia
Surface profile evolution – 1 st 3 million axles Portorož, Slovenia
Mean Dynamic Force (k. N) Mean dynamic force – 1 st 3 million axles Distance (m) Portorož, Slovenia
Surface profile change – 1 st 3 million axles Portorož, Slovenia
Main profile changes – 1 st 3 million axles Portorož, Slovenia
Profile after 6 th, 7 th & 8 th million axles Portorož, Slovenia
Change in Profile (m) Change in profile after 6 th, 7 th & 8 th million axles Portorož, Slovenia
Mean Dynamic Force (k. N) Mean force after 6 th, 7 th & 8 th million axles Distance (m) Portorož, Slovenia
Mean Dynamic Force (k. N) Evolution of dynamic forces in pavement life Distance (m) Portorož, Slovenia
Profile Elevation (m) Evolution of profile during pavement life Distance (m) Portorož, Slovenia
Conclusions • Pattern of Statistical Spatial Repeatability changes during the pavement life • Pavements with the same properties (stiffnesses, etc. ) but different initial profiles have substantially different lives • Failure eventually occurs at a frequency that relates to applied force patterns Portorož, Slovenia
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