Experimental analysis on the consolidation of Tunis soft soil improved by multiple Prefabricated Vertical Drains

¹ Univ. de Tunis El Manar, Ecole Nationale d’Ingénieurs de Tunis, LR14ES03-Ingénierie Géo-technique, BP 37 Le Belvédère, 1002 Tunis, Tunisia
² Univ.de Carthage, Institut Supérieur des Technologies de l’Environnement de l’Urbanisme et de Bâtiment, 2 Rue de l’Artisanat Charguia 2 - 2035 Tunis, Tunisia.
³ Univ. de Tunis El Manar, Ecole Nationale d’Ingénieurs de Tunis, LR14ES03-Ingénierie Géo-technique, BP 37 Le Belvédère, 1002 Tunis, Tunisia Setec International 42-52 Quai de la Rapée Central Seine Building 75583 Paris Cedex 12. France

Abstract

The purpose of this paper is to experimentally investigate the consolidation of the reconstituted Tunis soft soil ‘TSS’ improved by Prefabricated Vertical Drains PVD. After geotechnical characterization, a consolidation test with vertical loading is performed on a mutli-drains cell, i.e. cell with soil improved by three drains installed in triangular pattern. The PVD used in this study is the Mebradrain 88 (Mb88) type which is commonly used in previous soil improvement projects in Tunisia. The test is conducted through a specific laboratory test apparatus “consolidometer”. The settlements of soft soil specimen were measured during the consolidation test. Soil samples were extracted from different positions to measure water content ω variation after consolidation test. Results show that a significant water content reduction is observed after consolidation tests (approximately 64%) mainly at the vicinity of the PVD. Finally, the assessment of consolidation settlement was investigated using Asaoka’s method. It’s found that the ultimate settlement predicted by Asaoka method showed a good agreement with the measured value with difference less than 1%.