Investigation on the Use of Equivalency Factors for the Design and Evaluation of Flexible Airfield Pavements

摘要

With over 1.5 billion square feet of airfield pavements in its portfolio, the U.S. Air Force has a vested financial interest in refining its design, maintenance, and inspection criteria to increase the efficiency of its investment in its infrastructure. As part of its strategic pavement assessment, the Air Force is currently moving to adopt the new design method (CBR-Beta) developed by the U.S. Army Corps of Engineers (USACE) on the basis that the new methodology more accurately represents the performance of flexible airfield pavements, particularly with newer, heavier aircraft. Supporting this adoption of the new method, this research primarily focused on evaluating the current set of equivalency factors in use by the Air Force and the USACE using a meta- analysis approach. Building on this initial success, the research shifted to analyzing the life-cycle costs of the various flexible pavement design methods relative to a common design standard to eliminate the problems associated with comparing the methods each with its own assumptions and processes. Looking to further refine the predictability of the CBR-Beta method, the research analyzed the formulation of O.K. Frohlich's concentration factor. Additionally, the research assessed the possibility of expanding the empirical airfield data set with highway testing data. Ultimately, this research led to recommending new equivalency factors for stabilized layers, a new two-layer concentration factors model, an extension to CBR-Beta for highway pavements, and provides evidence to reformulate Beta as a stress-derived variable as opposed to failure- derived.