MEASURED PAVEMENT RESPONSE TO TRANSIENT AIRCRAFT LOADINGS

THOMAS DALE WHITE, Purdue University

Abstract

A testing program was designed and undertaken to collect pavement deformation response to aircraft traffic. Linear variable differential transducers (LVDT's) were installed in an active taxiway at Kirtland Air Force Base, Albuquerque, New Mexico. The LVDT's were attached to reference rods anchored at 16, 36, 120, and 209 in. Results were basic pavement responses, information on how pavement layers accommodate dynamic loads, as well as data to compare vertical deformations predicted by a theoretical model. As shown in this study, pavement deformation at a particular offset may display a range of possible values depending on the pavement's traffic history. Additionally, the conventional negative or downward deformation of a loaded pavement cross section can be a net summation of vertical extension (tension) and compression in horizontal zones of the pavement except immediately under a wheel where compression occurs in all horizontal zones. Net extension is recorded in a zone at least 36 in. deep. At 120 in. there is a net compression. The difference between a pair of gages in different events may agree, even though extension is recorded by one of the gages in an event. For example, within a range of offsets that depict similar deformation patterns, the difference between gages 1 and 2 is approximately the same from one event to another, even though one gage records net extension and another net compression or both record net compression. Rebound defines the pavement's initial state for the next application of load. The rebound may be a positive or negative residual. Both testing experience with nondestructive testing equipment and actual aircraft indicate significant energy is dissipated in the pavement surface. Laboratory tests and procedures recommended in the literature were used to develop input for an N-layered elastic model. Additional input values were assumed in an attempt to predict measured surface deflections under the wheels of a B-727 aircraft. A finite difference solution was used to predict pavement temperatures. The solution is shown to have limited application for predicting pavement temperatures. The pavement response phenomena reported are significant. They expose pavement responses that have been minimized in past research but must now be considered. Current theoretical models used in pavement analysis or design are limited in predicting pavement response phenomena. They do not represent the observed compression and extension in a pavement under and away from actual aircraft loads.

Degree

Ph.D.

Subject Area

Civil engineering

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