The prediction models of permanent deformation under repeated load for unbounded granular aggregate and subgrade soil
Professor, Department of Road and Airport Engineering
Tongji University, 1239 Siping Road, Shanghai 200092, People’s Republic of China
Tel.: (86-21)-6598-1430, Fax: (86-21)-6598-1430,
Unbounded granular aggregate could cause unrecoverable deformation under repeated load, and then pavement will be damaged rapidly. First, some kinds of permanent deformation prediction models are compared and analyzed. Second, test the permanent deformation of a common unbounded granular aggregate changing different water contents using dynamic tri-axle method on the UTM100 testing system. Lastly, based on the deformation curve, through regression method, get the prediction models and analyze the effect of water content on the permanent deformation of unbounded granular aggregate.
According to the asphalt pavements widely used in China and some specifications of America, such as LTPP P46-96, NCHRP 1-28 and NCHRP 1-28A, the proposal for the permanent deformation test of subgrade soil in China was put forward. One model was proposed in 2002 AASHTO Design Guide to predict the permanent deformation of subgrade soil. This model includes only two parameters and has been field calibrated in MnRoad. What’s more, the results got through the model were very close to the results got through the laboratory tests carried out in China. For the reasons above, the permanent deformation model for subgrade soil in 2002 AASHTO Design Guide was recommended to be used in China.
PRESENTER’S QUESTIONS: I would like to receive comments, suggestions, and feedback from the meeting's attendees on the following matters:
1. How to realize the permanent deformation characteristic based on the test data and different prediction models of unbound granular aggregate?
2. When the permanent deformation model of subgrade soil has been determined by the test data, how to consider the design index of compress strain on the top of the subgrade based on the model?
PRESENTER’S STATEMENT: This work is still in progress, and has not been submitted for presentation or publication at another meeting.