Aims/hypothesis One of the critical mechanisms determining creep in granular materials is the bre... more Aims/hypothesis One of the critical mechanisms determining creep in granular materials is the breakage of soil particles. This study aims at evaluating the time-dependent creep deformation of calcareous sand at low effective stress conditions. Methods K0 creep tests were performed for both calcareous and silica sands at low stresses of 65 and 120 kPa, and the results of creep tests were compared with the results of constant rate of strain (CRS) tests at high stress levels up to 12 MPa. For a quantitative evaluation of the effect of the particle breakage on the creep deformation of calcareous sand, the relative breakage ($$B_{r}$$ B r ) was determined based on the results of sieve analyses. Results The results demonstrate that Tunisia calcareous sand experiences significant particle breakage during creep and the consequent creep deformation at low stress level. The determined $$B_{r}$$ B r after creep at low stress level is comparable with that after the CRS test at high stress level...
Soil Testing, Soil Stability and Ground Improvement, 2017
The present paper comments on the evaluation of the initial stiffness of sensitive soft soils as ... more The present paper comments on the evaluation of the initial stiffness of sensitive soft soils as an outcome of several testing methods: Resonant Column (RC), Bender Element (BE) tests, Seismic cone tests and Empirical relationships (correlations). The RC, BE and common geotechnical laboratory tests were carried out on soft clays adjacent to the Tunis Lake in Tunisia. The database was completed making use of existing studies carried out on other types of Swedish soft clays from the literature related to seismic cone tests. A number of empirical correlations for determining the initial value of the shear modulus of soils in the literature was adopted in order to re-analyze the available data set. The authors suggested an adapted empirical lower bound correlation aiming at evaluating the analyzed soft soils' small strain shear modulus (G max), probably even useful for less undisturbed sampling. The proposed equation aims at giving an indication of the effect of, for example, the mean effective stress (p′) and the corresponding void ratio (e) on the initial soil stiffness more clearly.
Soil particle shape analysis was conducted on two calcareous sands from Dissa and Matmata in Tuni... more Soil particle shape analysis was conducted on two calcareous sands from Dissa and Matmata in Tunisia and one silica sand from Jumunjin in Korea using an image analysis method. This technique uses complex Fourier shape descriptors and image analysis of sand grains SEM photographs to provide accurate quantification of particle morphology and texture. The Fourier descriptors, denoted “Signature Descriptors”, provide measures of Elongation, Triangularity, Squareness, and Asymmetry and identify the overall shape of soil particles. A summary of higher-order descriptors provides textural information linked up to local roughness and texture characteristics. After analyzing the Fourier descriptors, elongation was found to be the major characteristics of the three sands, mainly for the Dissa and Matmata carbonate sands. In addition, the elongation signature descriptors for the Dissa and Matmata sands have very high values compared to those of Ras Alkhair (Saudi Arabia) and Dog’s bay (Ireland)...
Les argiles molles de Tunis Etude de la sensibilité
L'objectif de ce travail consiste à étudier le comportement des argiles molles de Tunis (amT)... more L'objectif de ce travail consiste à étudier le comportement des argiles molles de Tunis (amT) et la détermination des caractéristiques physiques et mécaniques relevantes. En effet, l'identification des paramètres physiques, minéralogiques, sédimentologiques et mécanique, d'une part, et l'étude du comportement mécanique des amT, d'autre part, a permis dans un premier volet d'estimer le degré de sensibilité de divers argiles molles de Tunis et suggérer le processus qui a conféré à ces argiles leur métastabilité. Un modèle physique de développement de la sensibilité dans les amT a été élaboré. Les classifications (selon la sensibilité) suggérées par plusieurs auteurs, montrent une divergence des résultats. La proposition d'une classification propre aux amT a été élaborée. Dans un deuxième volet l'étude du comportement mécanique des amT a permis d'abord de confirmer le caractère métastable de ces argiles; ensuite de trouver l'impact de la sensibil...
In Tunis City, the sensitivity of the marine deposits at shallow depth (z = 0-20 m) varies signif... more 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.
L'objectif de ce travail consiste à étudier le comportement des argiles molles de Tunis et l... more L'objectif de ce travail consiste à étudier le comportement des argiles molles de Tunis et la détermination des caractéristiques physiques et mécaniques relevantes. En effet, l'identification des paramètres physiques, minéralogiques, sédimentologiques et ...
Ga onmiddellijk naar paginanavigatie. Tunis soft soil sensitivity. Please use this identifier to ... more Ga onmiddellijk naar paginanavigatie. Tunis soft soil sensitivity. Please use this identifier to cite or link to this item: Record Details. Record ID, 804906. Record Type, conference. Author, Lamia Touiti; Mounir Bouassida; William Van ...
The present experimental investigation aims at investigating the small strain stiffness of calcar... more The present experimental investigation aims at investigating the small strain stiffness of calcareous sand as a function of applied stress. The calcareous sand was sampled at Tunisia's Dejebel Dahar region, and the shear wave velocity (Vs) of calcareous sand was measured using modified oedometer cell equipped with bender elements. The results of this study demonstrate that the Vs of the tested calcareous sand is smaller than that of silica sand with minimal crushable particles at relatively low applied stress (σ); however, Vs of calcareous sand is greater than that of silica sand at high σ, reflecting strong dependency of calcareous sand on σ. The applied stress dependency of soils can be expressed as a power function of applied stress (Vs = α (σ / 1 kPa)β, where α = Vs at σ = 1 kPa and β = stress exponent). Generally, the single α-β can capture the dependency of Vs on σ, and the typical β value for sand is around 0.25. The measured β of tested silica sand was around 0.20; while...
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