FWD Analysis of Pavement Sections with Geotextile Separators

摘要

In an effort to quantify the contribution of geotextile separators to the long-termrnperformance of pavement sections, falling weight deflectometer (FWD) testing wasrncarried out over a 12-year period at a test section in southwest Washington State.rnFive different geotextile separators as well as a soil-only control section wererninstalled in the test section with a different base course thickness in the two lanes of arnlow volume but heavily loaded rural state highway. The performance of thernseparators was evaluated during construction and 5 and 12 years after construction.rnField and laboratory tests were conducted on the subgrade, granular base materials,rnand the geotextiles as part of the effort to correlate the performance of the pavementrnsection to the presence of the geotextile separators. As part of the most recentrnevaluation, the FWD results were analyzed using two recently developedrninterpretation methods, the FWD Area Program (version 2.0) and Evercalc PavementrnBackcalculation Program (version 5.20).rnThe results from the FWD Area Program generally showed a decrease in the adjustedrndeflections, and increases in the area parameter and subgrade modulus along the testrnsection over the 12-year period. The greatest increase in subgrade modulus occurredrnin the six months following construction. The control sections exhibited behaviorrnsimilar to the sections with geotextiles, suggesting that for relatively thick pavements,rngeotextiles separators may not provide a significant contribution to the long-termrnperformance of the pavement.rnThe Evercalc backcalculations indicated an increase in the adjusted pavement andrnsubgrade moduli over the 12-year period. The sections that contained geotextilesrngenerally showed an increase in the base course modulus, however, some of thernanalyses showed little to no increase in the base modulus in the control (soil only)rnsections. The results suggest that geotextiles might contribute to an increase in thernbase course modulus over time. These findings were also correlated with the resultsrnof the field and laboratory investigations.