Modified deflection ratio procedures for backcalculation of concrete pavements

摘要

The main objective of this study was to develop a general purpose rigid pavement backcalculation program for various nondestructive deflection testing (NDT) devices. The study strives to minimize the maor limitations and deficiencies of traditional backalculation procedures by modifying the most widely-used AREA defection basin concept. A modified deflection ratio (W/W_o) backcalculation procedure is introduced using the ILLI-SLAB finite element (F.E) program and the principles of dimensional analysis. Prediction models were developed using the proejction pursuit regression technique for the modifed deflection ratio. Subserquently, the proposed backcalulation procedure was implemented in a user-friently backalculation program (TKUBAK) to expand its applicability for any different NDT loading radius, sensor locations, finite slab sizes, as well as locations of loading plate (interior, edge, and corner of the slab). The effects of random error in deflection measurements, a second layer, a temperature dieffential, and adjacent slabs on backcalculation should be further investigated to account for more practical pavement conditions.