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ACCELERATED CHARACTERIZATION OF FULL-SCALE REINFORCED FLEXIBLE PAVEMENT MODELS USING A VIBROSEIS | ||||
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Brady Cox, Ph.D., P.E. John McCartney, Ph.D., P.E.
July 1, 2008 - June 30, 2009
Geosynthetic basal reinforcement has been used in flexible pavements to limit the occurrence of rutting,
fatigue, and environmental-related cracking, and to permit reduction in base course thickness. However,
the lack of an accelerated test to evaluate the behavior of full-scale pavement test sections in an
economical and representative manner has limited our understanding of the role of variables that may
affect the performance of basally-reinforced flexible pavement. Current accelerated tests involve either
cyclic plate load tests or heavy vehicle simulators. Cyclic plate load tests often have scale effects,
while heavy vehicle simulators require significant space, high construction cost, and long durations.
These shortcomings have prevented parametric analyses of important variables such as pavement geometry,
geosynthetic properties, depth of geosynthetic placement, stress state, and load (magnitude and frequency).
The research objective of this study is to develop and validate a new accelerated testing approach to
characterize full-scale pavement models with the capability of considering these variables in a timely
manner. Specifically, this study will involve construction of full-scale pavement test sections which will
be characterized using a vibroseis (shaker truck). The vibroseis can apply static wheel loads as well as
dynamic normal and shear loads at selected frequencies. In the tests, dynamic loads will be applied to the
pavement surface, and nonlinear stiffness-strain relationships for the pavement layers (base, geogrid, and subgrade)
will be inferred using geophones and suction sensors embedded at different depths in the pavement section. This
information will be useful to perform long-term dynamic modeling of pavements. Cycles of ESALs will then be
applied until pavement failure is observed, similar to traditional heavy vehicle simulator tests. Accordingly,
this test is expected to be faster and yield more useful information than existing tests, while still
maintaining representative loading conditions. An important component of this study will be the selection of the
geometry of the test sections and the characteristics of the applied loads to ensure test conditions representative
of actual pavements. This study will only involve the development and validation of this testing approach. However,
future projects will apply this new test in parametric evaluation of design alternatives, permitting selection of
the optimal pvement design before implementation in the field. Information from such tests can be used to develop
design guidelines for reinforced pavements, perform cost-benefit design analyses, evaluate the impact of environmental
variables in a controlled setting, and calibrate design codes for lifetime prediction of reinforced pavements (MEPDG).
TRB Keywords: Geosynthetics, Soil Stabilization, Flexible Pavements.
Product: In Progress (MBTC-3013)
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