Studies On Analysis Of Airfield Pavement And Its Application Into Structural Monitoring

Under the long-term effect of aircraft wheel loads and natural deterioration, airport pavement will undergo distress to a certain extent, which is the hidden danger to airplane taking off and landing. The main health monitoring method for airport pavement is to use the Falling Weight Deflectometer(FWD) or the Rolling Wheel Deflectometer(RWD) to measure the deflection of several points on the surface of pavement when the testing load is applied. Then, the analysis is performed so as to detect the bearing load capacity of the pavement from these data. By taking use of the so-called inertial point(IP) the multivariable recognition problem on pavement structures is expected to be simplified. But current studies on pavement recognition based on IP are insufficient. Especially, the related studies on theoretical analysis, appraisal of complex pavement structures, field investigations are required.First of all, the bending differential equations of infinite or finite single or double-layer plate model on the Winkler or two-parameter foundation model are solved using the analytical method to obtain theoretical deflection curve. Then, using the FEM method influence factors on IP have been studied. The main factors that affect the IP of pavement are analyzed. After that, the inversion method of double-layer pavement structure based on IP is carried out by establishing the regression formula between the thickness of slab and subgrade reaction modulus(SRM) through.NET programming frame and secondary development of ANSYS, and determining method how to choose the initial value for the inversion. Further, the proposed acquisition method is applied to examine the airport pavement of East China Airport. Finally, in order to realize the automated detection of the whole pavement, a structure health monitoring system based on GIS(Geographic Information Systems) had been developed. The following conclusions are drawn up:(1) By means of Gauss-Legendre numerical integration and.NET programming the existence of IP on infinite pavement plate under a circular uniform load or finite pavement plate under free boundary condition and double axisymmetric load has been proved by theoretical and FEM analysis. IP is only relevant to SRM, but independent on the elastic modulus of the pavement slab.(2) FEM analysis has shown that there exists IP for the single or double-layer plate on the Winkler foundation model. The distance of IP from the central point of the slab and the deflection of IP are influenced by parameters of the subgrade model, the size of slab, the moving speed of the monitoring device on the pavement, but the density of the slab, Poisson's ratio, the elastic modulus of the base and damping of subgrade make little effects.(3) The inversion method for SRM of airport pavement structure by using such parameters as the distance and the deflection of IP has been brought out. The algorithm using the fitting deflection curve from the FWD test and the regressive formula between parameters of IP and SRM and thickness of the slab can solve the selection of the initial value of IP in the procedure of inversion.(4) The analysis program is used to perform the monitoring of airfield pavement in East China Airport. The testing result is consistent with that obtained using the commercial TJBACK analysis software, indicating the feasibility of the detection method based on IP. This program combined with GIS technology has realized the health monitoring of the whole for airfield pavement.