Propriétés géotechniques de quelques formations géologiques propices aux glissements de terrains dans l'agglomération de Constantine (Algérie)

Résumé

L'étude présentée se compose de deux parties. La première explique certaines formes de glissement de terrain observées dans l'agglomération de Constantine comme témoins d'une activité néotectonique. La seconde partie présente quelques caractéristiques géotechniques, des formations géologiques instables, obtenues par différents moyens: les essais de laboratoire, les essais in-situ, les corrélations.

Abstract

 The article can be conveniently divided into two parts. The first part of the paper describes certain forms of landslides observed in the urban area of Constantine which indicate neotectonic activity. The detailed surveys of present and fossil ground movements showed the geological formations to be of Mio-Pliocene age and to consist of two lithological groups: clayey marls and conglomerates. The slope terrain and potential for instability varies considerably with the two lithologies. The clayey-marl group contain local sand and gravel horizons of varying thickness. These water-bearing levels are confined and hence if the natural egress points become blocked, the increased water pressure within the material causes instability. Landslides rarely occur within the conglomerates, even when they are at quite steep angles. However, where conglomerates are found interbedded with the marly sediments, significant landslides can take place, The location and geology of the El Menia (1), Bardo (2), Aouinet El Foul (3) and Oued zied (4) slides are presented. The second part of the paper presents some geotechnical characteristics of the unstable geological formations, obtained by in situ and laboratory testing and the correlations drawn between them.