AN OVERVIEW OF DEFLECTION PARAMETERS FOR PERFORMANCE ANALYSIS

Structural analysis of pavements, particularly with respect to bearing capacity, is one of the most significant aspects of pavement management; transportation engineers have, for many years, focused on developing rational design schemes that accurately predict pavement structural performance. Rational analyses of pavement performance are performed within the framework elastic and viscoelastic theories and take into account the magnitude of stresses, strains, and displacements. The magnitude of the stresses and strains induced in a pavement system have long been recognized as indicators of pavement performance. The occurrence of fatigue cracking, rut depth and disintegration within the pavement structure are associated quantitatively with the magnitudes of stresses and strains within a pavement layer system. However, measurement of these quantitative indicators (stress and strain) and/or their components which are related to the distress manifestations are not easily achievable unless sophisticated instrumentation is used in the procurement of the data. In lieu of stress and strain measurements in the field, measurements of pavement surface deflection and surface curvature have been universally recognized as indicators of performance and numerous field investigations have been performed to develop the relationships between distress and deflection, using A number of methods which include: (1) bearing tests; (2) static deflection techniques; (3) dynamic deflection tests; (4) impact tests; (5) wave propagation tests. The deflection of a pavement system and its curvature under load are influenced by many variables, including moduli and thickness of pavement components, the geometric ratio of load radius to pavement thickness, load magnitude, and the moduli ratios. Pavement deflections and curvature are commonly employed for structural analysis, bearing capacity calculations, and estimations of the life expectancy of pavement systems.(a) the covering abstract for the