Pavement damage due to heavy loads on thaw weakened flexible pavements is a major
concern for road agencies in Western Canada. To protect weaker, low volume roads,
agencies impose spring weight restrictions (SWR) during the spring thaw to reduce
pavement damage. While SWR may be cost effective for highway agencies, reducing the
spring weight allowances can have a major impact on truck productivity and shipping
costs. Therefore an improved process that links SWR loads to pavement damage, and
based on limiting failure strain, is required.
This thesis developed Local mechanistic-empirical damage models to predict fatigue and
rutting failure on two spring weight restricted (SWR) flexible pavements in Manitoba.
The Local damage models were used to assess the SWR loads that regulate commercial
vehicle weights in Manitoba based on a limiting strain relationship between truck loads
and damage. The Local damage models and a calibrated Finite Element Model (FEM)
were used to predict the equivalent single axle load (ESAL) repetitions to fatigue and
rutting failure at varying B-Train axle loads at the Manitoba sites. The Local model
predictions were compared to predictions from the Asphalt Institute (AI) and Mechanistic
Empirical Design Guide (MEPDG) damage models. The results of the analysis showed
that for each 1% increase in load, there was a corresponding 1% increase in strain, and up
to 3% decrease in ESAL repetitions to failure, depending on the Local, AI, or MEPDG
damage models. The limiting failure strains, computed from the Local model for design
ESALs of 100,000, were 483μm/m and 1,008μm/m for fatigue and rutting failure,
respectively. For the Manitoba sites, the predicted FEM strains at B-Train normal and
SWR loads were higher than the Local model limiting strains. Therefore the Manitoba ii
SWR loads regulating B-Train operations on the two pavements during the spring period
appeared to be reasonable. It is recommended that the research findings be verified with
further calibration and validation of the Local damage model using a larger data set of
low volume flexible pavements. A strain-based concept on how to manage the SWR
regime in Manitoba based on the limiting strains was developed and presented.
| Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/21691 |
| Date | 27 June 2013 |
| Creators | Kavanagh, Leonnie |
| Contributors | Shalaby, Ahmed (Civil Engineering), Rasmussen, Peter (Civil Engineering) Clayton, Alan (Civil Engineering) Luo, Yunhua (Mechanical Engineering) Zaniewski, John (Civil Engineering West Virginia University USA) |
| Source Sets | University of Manitoba Canada |
| Detected Language | English |
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