BACK ANALYSIS TECHNIQUES FOR PAVEMENT CONDITION DETERMINATION --BEARING CAPACITY OF ROADS AND AIRFIELDS. PROCEEDINGS OF THE 2ND INTERNATIONAL CONFERENCE, PLYMOUTH, ENGLAND, SEPTEMBER 16-18, 1986

The highway maintenance engineer wishes to determine the structural integrity of a road pavement by non destructive means. Various methods have been employed ranging from the purely empirical, based largely on the transient deflection of a pavement under a known moving wheel load, to the analytical, based on the full transient deflection bowl obtained under either a known moving wheel load or such devices as the falling weight deflectometer. Considerable research has also been effected into materials characterisation which allows different materials to be modelled in computer representations of pavement structures. However, whilst it is known that pavement materials do not behave in a simple linear elastic manner, most analytical techniques rely on this linearity. Furthermore it is clear that many pavement structures, that are the subject of investigation in the maintenance process, have inadequate records from which to deduce layer thicknesses and characteristics. A critical study of certain of these methods is given. In addition a sensitivity study is undertaken which indicates the effect of inappropriate assumptions regarding material behaviour and pavement geometry. As a result of this, recommendations are made on the use of transient deflections combined with analytical techniques to minimise the risks inherent in such methods.(a) for the covering abstract of the conference see IRRD 815528.