El Khadir Lakhal

Optimization of the maintenance strategies of roads in Morocco: calibration study of the degradations models of the highway development and management (HDM-4) for flexible pavements

ABSTRACT The Highway Development and Management 4 (HDM-4) model was developed by the World Bank and used for pavements management system. An approach of the adaptation to local conditions is therefore required by adjusting the calibration factors, with the consideration of the context in which they are to be applied. The aim of the present work is to suggest these calibration factors for predicting the deterioration (structural cracking, ravelling, potholes and their resultant roughness) of roads in Morocco. The careful choice of such maintenance work planning is based on the result of these models. This study is based on the exploitation of road database, obtained from visual inspections and measurements performed by the National Center of Road Study and Research. The monitoring covered 6 years and concerned 55 test sections located on the Moroccan territory. Four kinds of structures were analysed involving different pavement bodies, constituting materials and thicknesses. The used method is based on a statistical analysis using equations implemented in HDM-4 models. The calibration process of the pavement behaviour was performed by a linear regression between the predicted values and observed values. Thereafter, the calibration factors for the initiation and the propagation of each damage in the models were determined. The obtained results allow us performing a quite good calibration for a pertinent use of HDM-4 in the local context.

Approximate Analytical Solution for One-Dimensional Solidification Problem of a Finite Superheating Phase Change Material Including the Effects of Wall and Thermal Contact Resistances

This work reports an analytical solution for the solidification of a superheating phase change material (PCM) contained in a rectangular enclosure with a finite height. The analytical solution has been obtained by solving nondimensional energy equations by using the perturbation method for a small perturbation parameter: the Stefan number, . This analytical solution, which takes into account the effects of the superheating of PCM, finite height of the enclosure, thickness of the wall, and wall-solid shell interfacial thermal resistances, was expressed in terms of nondimensional temperature distributions of the bottom wall of the enclosure and both PCM phases, and the dimensionless solid-liquid interface position and its dimensionless speed. The developed solution was firstly compared with that existing in the literature for the case of nonsuperheating PCM. The predicted results agreed well with those published in the literature. Next, a parametric study was carried out in order to study the impacts of the dimensionless control parameters on the dimensionless temperature distributions of the wall, the solid shell, and liquid phase of the PCM, as well as the solid-liquid interface position and its dimensionless speed.