Abstract

Dynamic Probing Test (DPT) allows a fast and economical soil strength characterization. However, its analysis is based on different theoretical-empirical approaches, which yield, at same conditions, no reliable results. The purpose of this article is to evaluate the reliability of dynamic cone resistance () obtained with different conventional methods based on Newtonian and wave equation approaches. For this purpose, an instrumented dynamic penetrometer (P.A.N.D.A.3) is employed. Its fundamental principle is to measure (for each blow throughout the driving) strain, acceleration and displacement at the anvil in order to separate the waves that propagate into the bars. It allows to reconstruct the dynamic load-penetration curve at cone/soil interface. A simple elastic-perfectly plastic Mohr-Coulomb model enables to obtain from each curve the dynamic and pseudo-static resistance, dynamic rigidity, mechanical impedance as well as wave velocity of soils. To evaluate the performance of different methods and to propose a more realistic approach, the results of a series of tests carried out in a calibration chamber (state) on Fontainebleau's sand are presented. For each sample, density samples and vertical pressure varies. Cone resistance were then compared. Experimental tests were performed with instrumented DPT and CPTu test in two sand embankments. Comparison between static () and dynamic () cone resistances obtained with different approaches is presented. The results show differences between the results obtained by the methods considered. However, it is possible to conclude that the methods based on wave analysis and DCLT curve allow a more realistic result to be obtained. RÉSUMÉ : L'essai de sondage dynamique (DPT) permet une caractérisation rapide et économique de la résistance des sols. Cependant, ses analyses sont basées sur différentes approches théoriques-empiriques, qui ne donnent, dans les mêmes conditions, aucun résultat fiable. Le but de cet article est d'évaluer la fiabilité de la résistance dynamique du cône () obtenue avec différentes méthodes conventionnelles basées sur les approches newtoniennes et de l'équation des vagues. Dans ce but, un pénétromètre dynamique instrumenté (P.A.N.D.A.3) est utilisé. Son principe fondamental est de mesurer (pour chaque coup tout au long du battage) la déformation, l'accélération et le déplacement au niveau de l'enclume afin de séparer les ondes qui se propagent dans les barres. Il permet de reconstruire la courbe dynamique charge-pénétration à l'interface cône/sol. Un simple modèle de Mohr-Coulomb élastique-parfaitement plastique permet d'obtenir à partir de chaque courbe la résistance dynamique et p​s​e​u​d​o​