Geotechnical Testing Journal

Geotechnical and Geological …, 2009

In Tunis City, the sensitivity of the marine deposits at shallow depth (z = 0-20 m) varies significantly. The influence of the process of the leaching out of Tunis soft soil on its geotechnical parameters is a focal point in this research. This process leads finally to moderate levels of sensitivity for Tunis clays since it appears to happen in a two steps with increasing sensitivity. The ''hard water'' leaching out and the dispersive action of organic matter (humus) lead unexpectedly to higher but still moderate level of sensitivity as measured on many Tunis sites. These sensitivity variations result from the combination of leaching out with hard ground water and high content of organic matter. This sensitivity attracted our attention and remains of high interest for the study of the behaviour of the Tunis soft clay.

Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 50 No. 4 December 2019 ISSN 0046-5828, 2019

Tunis soft clay being known as one of the most problematic soils has poor mechanical characteristics, high compressibility and exhibits fragile shear strength. This paper considers the geotechnical characterization of Tunis soft clay by compiling results from in situ and laboratory tests. Accordingly, some correlations are suggested. The assessment of observed behaviour of Tunis soft clays in the zone of interchange ramps was investigated. The follow up of ramps behaviour was performed for a period of three months. The evolution of settlement was monitored by rod settlement, hydraulic settlement and multi-points settlement. A plane strain model was built for numerical investigation conducted by Plaxis software to simulate the behaviour of the ramp's embankment. Hardening Soft Soil Model (HSM) and Soft Soil Model (SSM) were adopted for the soft clay layer. The results showed an agreement between the predictions of the two models of the behaviour of the soft clay. Using measured settlement, the adopted behaviour for Tunis soft clay is justified.

International Journal of Geomate, 2012

Soft clays represent a well known category of problematic soils which are generally encountered under the form of deposited layers in coastal areas. Several problems are faced when dealing with the study of soft clays from field investigation, soil characterization, behavior modeling, and stability of geotechnical structures up to ground improvement solutions. Studying the behavior of soft clays especially requires a thorough determination of their geotechnical parameters. Hence, it is needed to carry out laboratory tests on extracted specimens either from cored samples or remolded samples in laboratory. Recent studies on Tunis soft clays have been conducted in order to address essentially their geotechnical characterization and mechanical behavior. Tunis soft clay is a problematic soil because of its weak strength characteristics and high compressibility. Then, designing foundation on Tunis soft clay requires a thorough study especially for the short term behavior and for the long term behavior as well. At the National Engineering School of Tunis, early in the eighties, the first investigation [11] had been dedicated to the analysis of dynamic behavior of undisturbed cored samples of Tunis soft clay subjected to torsional shear. Later, in the nineties, [6] has investigated the geotechnical properties and behavior of scaled models made up of remolded Tunis soft clay reinforced by sand columns. In the last decade special care was accorded to the study of the behavior of Tunis soft clay by performing experimental works and conducting numerical computations of various soil mechanics applications, [23]. This paper, first, introduces in brief the geological aspects of Tunis City. Then, the identification and the classification of Tunis soft clay are briefly described. Second, recorded results from oedometer and triaxial tests conducted on Tunis soft clay samples are presented. Third, numerical results of a high embankment resting on Tunis soft clay are analyzed, and finally the feasibility and the design of ground improvement techniques (vertical drains, stone columns) is illustrated through selected Tunisian case histories. It has been described, [21], in details the history of geological geotechnical context of the ancient Tunis City that was built on a depression surrounded by hills. The old town was established in the southern side, and the new residential suburbs are located in the north. The plateau is identified as an important deposit of the recent Quaternary age that includes sandy levels and is overlaid by anthropogenic formations. The recent Quaternary is resting on clayey to sandy-clay layer of ancient Quaternary. This latter represents the rigid stratum of Tunis City. The alluvial sedimentation in the Tunis estuary can be associated with simultaneous intensive subsidence, [16]. The lagoon depressions, nearby lake-Essijoumi and the Lake of Tunis, are generally filled with mud of the recent Quaternary and of clayey sand or silt sand of the riverbeds. Divergent displacement of Medjerda and Méliane riverbeds during the recent Quaternary are the consequence of a synchronous upward block displacement of the Tunis region. Thereafter, the soft deposits were filled up to create the zones of urban extensions with anthropogenic formations of thickness varying between 1 and 8 m. The analysis of geotechnical and electronic atlas maps and the geological profiles deduced from the geotechnical and geological information system (GGIS), [9], has conducted to the subdivision of Tunis City in four homogeneous zones: I, II, III and IV. Three main formations constitute the soil of Tunis plateau (zone I): a heterogeneous fill layer of variable thickness 1 to 8m, the muddy complex and the sandy-clay complex that is assumed as a rigid stratum.

The marine environment deposits of Tunis soft soil during the quaternary age and the abundance of non swelling minerals (quartz) resulted in a low electro-kinetic potential and a flocculated structure. The Tunis soft soil leached out afterwards under "hard" ground water (cations Ca 2+ ) conditions, leading finally to pore water quality with a high concentration of polyvalent ions and therefore with limited possibilities to developing highly sensitive clay. At locations where Tunis soft soil remained in contact with active organic matter, increasing the negative charges at the particle surface, the double layers around the particles were expanding. The electro-kinetic potential became higher, implementing larger repulsive forces between particles. At any type of remoulding of such type of soft soil, these forces will prevent flocculation of the clay particles. This reduces remarkably the remoulded shear strength and therefore largely increases the sensitivity of the clay leading to high sensitivity of many of the Tunis soft soils. The levels and the origin of such sensitivity in Tunis soft soils are going to be pointed out.

The need for urban growth and development has been driving man to occupy areas once considered improper or of low interest, due to the presence of low-resistance and highly compressive soft soil. Nowadays it is possible to improve soil by installing prefabricated vertical drains (PVD) with geosynthetics. These drains can also be assisted by applying vacuum, equivalent to the pressure of an embankment up to 4m high, but with less need for earth movement to mobilize and demobilize the temporary overload. This technology is being applied in a highway construction in an alluvial soft soil deposit extending for over 100 km, currently in progress in Latin America. Several undisturbed samples were extracted and tested in laboratory to determine soil compressibility and consolidation time. To assess the efficiency of the methods employed for sampling and molding specimens, quality indexes of consolidation tests carried out in the highway construction site are presented. Given the variable nature of this soil formation, back analyses were carried out to assess the compressibility and consolidation time of the alluvial soft soil.

International Journal of Engineering and Technology, 2012

Assessing the geotechnical parameters helps in improving the soil settlement which usually causes damage to the civil structure. In this study, geotechnical investigations at UET, Kala Shah Kaku Campas (KSK), Lahore site are carried out for undisturbed samples at depths of 2 ft, 3 ft, 4 ft and 5 ft. in orderto soil classification and assess the consolidation parameters on undisturbed and disturbed/remolded samples. Results indicate that the soil grade from top layer of silty clay (CL-ML) to lean clay (CL) from 3ft to 5ft depth. The natural moisture content is very low and the plastic limit varies from 20 to 23. The liquidity index shows that the soil of the study area is of semisolid or solid state. Void ratio varies from 0.70 to 0.96 for undisturbed samples and 0.60 to 0.90 for disturbed samples. Specific gravity and Bulk density range from 2.68 to 2.69 and 14.0 to 16.0 kN/m 2 respectively. The over consolidation ratio (OCR) values up to 5ft depth are in the range of 4.1 to 7.0. It is found that compressibility characteristics decrease with depth. The coefficient of primary and secondary consolidation decreases with increase in applied pressure and tends to be more or less constant at high pressures.

Int. J. of GEOMATE, 2012

The design of foundations resting on Tunis soft clay still remains a very challenging issue to address. However some works have been dedicated to the characterization and the study of behavior of this problematic soil on which recent investigations more focused on improvement solutions. This paper first summarizes the geotechnical properties of Tunis soft clay on the basis of data collected from experienced projects and results obtained from laboratory tests. It has been discussed how Tunis soft clay properties can be affected by disturbance? Some correlations are also suggested from recorded data. Besides, the study of behavior of built embankments on Tunis soft clay is analyzed from numerical computations carried out by 2D version of Plaxis software. It is then concluded, that the improvement of Tunis soft clay by classical techniques like geodrains, sand piles and stone columns is necessary to guarantee the short term and long term stability of structures to be built on such weak soil. Illustrated case histories show the efficiency of these improvement techniques as competitive solutions compared to piled foundation that remains the most used especially for building projects in Tunisia but not cost effective.

Internal Report: Jimma University, 2025, 2025

This laboratory research study provides a comprehensive geotechnical characterization of black clay soil sampled at a depth of 3 meters from Jimma Town, Ethiopia. Carried out as a Master's degree academic project in Geotechnical Engineering at Jimma University (2025), the research study was conducted with the objective to provide important information on soil behavior required for foundation design and construction planning. The undisturbed soil sample was subjected to the laboratory test for moisture content, specific gravity, grain size distribution, Atterberg limits, soil classification, compaction, California Bearing Ratio (CBR), unconfined compressive strength (UCST), direct shear, swell index, permeability, consolidation, and in-situ field density tests. Standard test procedures were followed as per ASTM and AASHTO standards in order to ensure consistency in the methodology. Due to the disturbed nature of the sample, certain tests such as permeability and consolidation were limited in reliability, and therefore a second sample was utilized to improve the validity of the consolidation data. Please note that this study was conducted for academic purposes only, and due to time constraints and resource limitations, there could be slight inconsistencies or errors. Nevertheless, the study offers valuable data on the geotechnical characteristics of black clay soil in the region and serves as a baseline for further detailed research.

Southeast Asian …, 2010

In Tunis City, the sensitivity of the marine deposits at shallow depth (z = 0-20 m) varies significantly. The influence of the process of the leaching out of Tunis soft soil on its geotechnical parameters is a focal point in this research. This process leads finally to moderate levels of sensitivity for Tunis clays since it appears to happen in a two steps with increasing sensitivity. The ''hard water'' leaching out and the dispersive action of organic matter (humus) lead unexpectedly to higher but still moderate level of sensitivity as measured on many Tunis sites. These sensitivity variations result from the combination of leaching out with hard ground water and high content of organic matter. This sensitivity attracted our attention and remains of high interest for the study of the behaviour of the Tunis soft clay.

The study focus on the geotechnical characterization of Albanian soils by in situ and laboratory tests. In particular, Tirana Bussiness Park and Tirana Epoka University (Tirana, Albania) were investigated by means of boreholes, trial pists, standard penetration tests (SPT), seismic dilatometer test (SDMT), particle size analyses, oedometer tests, direct shear tests, triaxial tests, and unconfined compression tests. The paper illustrates the Sciacca method, an innovative procedure to carry out a SDMT test by using a drill rig as a penetrometer. In situ results were compared and integrated with laboratory geotechnical properties, both required for the design of the soilstructure interaction in Albania. These data would created an inventory useful for an information database of the geotechnical properties of Albanian soils and for the safe design of buildings. RÉSUMÉ L'objectif de l'étude sur la caractérisation géotechnique des sols albanais par des essais in situ et en laboratoire. En particulier, Tirana Bussiness Park et University Epoka (Tirana, Albanie) ont été étudiés au moyen de forages, PISTES des essais, des tests de pénétration standard (SPT), Essai au dilatomètre sismique (SGMPS), analyse granulométrique, oedomètre essais, essais de cisaillement direct, triaxial des tests et des essais de compression simple. Le document illustre la méthode Sciacca, une procédure innovante pour effectuer un test de SGMPS en utilisant une plate-forme de forage d'un pénétromètre. Résultats in situ ont été comparés et intégré avec laboratoire propriétés géotechniques, à la fois nécessaires à la conception de l'interaction sol-structure en Albanie. Ces données créé un inventaire utile pour une base de données des propriétés géotechniques des sols albanais et pour la conception sécuritaire des bâtiments.