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Analysis of the behaviour of a natural expansive soil under cyclic drying and wetting

  • Geremew Zemenu
  • Audiguier Martine
  • Cojean Roger
Original Paper

Abstract

Expansive soils swell and shrink regularly when subjected to moisture changes. Clayey soils are available worldwide and are a continual source of concern causing substantial damage to civil engineering structures. Cyclic expansion and shrinkage of clays and associated movements of foundations may result in cracking and fatigue to structures. In France, the damage caused by this phenomenon was estimated to be more than 3.3 billion euros in 2002 (Vincent in 3ème conférence SIRNAT-Forum des journées pour la Prévention des Risques Naturels, Orléans, janv. 2003) and the Paris region is one of the most affected. The objective of this study is to investigate the swell–shrink behaviour of a natural clayey soil considered to be responsible for a lot of damage observed on buildings in the Paris region, and thus contributing to the characterisation and understanding of expansive clayey soils. The studied soil, Argile verte de Romainville, is a lagoonal-marine deposit and is part of the Paris Basin Tertiary (Oligocene) formations (Fig. 1). It is a clayey soil sampled in the eastern region of Paris. The mineralogical and geotechnical properties of the soil are presented in Table 1. The soil contains quartz (15–20%), carbonates (12–20%) and traces of mica and feldspars. X-ray diffraction showed that carbonates are essentially dolomite and the clay minerals are dominantly illite, kaolinite and a small amount of smectite (Fig. 2). A grain size analysis shows that the clay content (<2 μm) varies between 78 and 80%. The study of its microstructure by means of the scanning electron microscope indicates that the clayey soil has structural elements oriented in the direction of bedding. The structure of the sample generally consisted of dense and continuous clay matrices with very limited visible pore spaces (Fig. 3). At its natural water content (w = 25%), the soil shows mainly a unimodal pore size distribution with an average pore radius of 0.07 μm and a very limited porosity with radii larger than 10 μm (Fig. 4). To assess the effect of suction on the simultaneous changes in void ratio and degree of saturation under zero external stresses, drying–wetting tests are performed on the natural samples. The osmotic technique (Polyethylene glycol solutions) and various salt solutions are used to control the suction values ranging from 1 to 300 MPa. Once equilibrium is reached at the given suction, the samples are weighed and their volume is measured. A synthesis of the drying–wetting paths is given on Fig. 5. The swelling potential of the soil is evaluated using both indirect (or empirical methods Tables 2 and 3) and direct methods. Swell percentage and swell pressure of the soil are measured in a conventional oedometer apparatus according to ASTM (D 4546-85). The test specimens are 70 mm in diameter and the height varies between 12 and 24 mm. The swell percentage is measured under a nominal pressure of 0.7, 2.0 and 6.3 kPa. Swelling pressure of the soil is measured by the conventional consolidation test method (free swell and load, ASTM D 4546-85 method A) and by a constant volume method (ASTM D 4546-85 method C). The test parameters and results for each specimen are given in Tables 4 and 5, and on Fig. 7. Cyclic swell–shrink tests are carried out on similar samples taken from the same monolith. A scheme that permits the study of the clayey soil behaviour at the extreme states of wetting and drying is chosen. The test begins by wetting the samples at their natural moisture content and density. When swelling is stabilized, the water is removed from around the samples and they are dried in an oven maintained at 45°C until the vertical deformation (shrinkage) is stabilised and are then rewetted and so on. Some experiments are stopped at different swelling phases for microstructural study of the soil. The test parameters of the specimens are given in Table 9 and the results are shown in Figs. 9 and 10. The evolution of the microstructure during wetting and drying cycles is investigated using scanning electron microscope and mercury intrusion porosimetry. Observations are made only on soil specimens taken at the end of the swelling phase of the selected cycles. In order to preserve the microstructure, the specimens are cut in small pieces, frozen by liquid nitrogen and finally sublimated. The results of the drying–wetting path including the water retention curve are shown on Fig. 5. The results show that on the drying path (in the void ratio versus water content plane) the soil first follows nearly the saturation line and then, as the water content decreases, the void ratio tends towards a constant value. A shrinkage limit of w = 14.5 % and a corresponding suction value of 15 MPa is deduced from this path. An air entry value of 10 MPa is obtained from degree of saturation versus suction curve. The wetting path shows that the wetting–drying path is reversible for suction values higher than 60 MPa. The different indirect methods used to assess the swelling potential of the Argile verte de Romainville show a general agreement with respect to its swelling potential ranging from high to very high (Table 3). Examination of the free swell test results shows that the Argile verte de Romainville exhibits swell percentage in the range of 15–26% and that its degree of swelling depends on the initial conditions (water content, dry density) and the applied load (Table 4). The higher the water content and the applied load, the lower the swell percentage. A specimen taken parallel to the bedding plane shows similar values of swell percentage with a steep volume change versus time curve indicating an anisotropy of permeability. The two direct methods used to assess the swelling pressure of the Argile verte de Romainville give different values (Table 5). The values obtained by the constant volume method are relatively close and are about 700 kPa. Lower values varying between 360 and 540 kPa are obtained by the conventional consolidation test (free swell-consolidation). This indicates that besides the initial conditions, the swelling pressure is strongly dependent on the stress path followed. The results obtained from the wetting–drying cycle tests show that the magnitude of the first swell cycle is controlled by the initial water content, the maximum deformation occurring on the second cycle and the stabilization of swelling deformation from the third cycle (Figs. 9, 10). Furthermore, the experimental data indicate that upon repeated wetting and drying, the swelling rate of the soil becomes faster, which is explained by an increase in permeability of the soil due to the development of preferential flow paths (micro cracks) on drying. With an increasing number of cycles, a permanent increase in the volume of the samples is observed. This suggests that the swelling–shrinkage behaviour of expansive soils is not completely reversible. Mercury intrusion porosimetry analysis and SEM observations before and after different numbers of cyclic swelling indicate that the swelling–shrinkage cycles are accompanied by a continual reconstruction of the soil structure (Figs. 11, 12). The mercury intrusion porosimetry results show that with an increasing number of wetting–drying cycles the pore volume and the average diameter of the pores increase progressively (Fig. 11). Larger modifications are observed in the pores with radius in the range of 0.1–5 μm. SEM observations also show further destruction of large aggregates and disorientation of structural elements as the number of cycles increases (Fig. 12). After the fifth cycle, the soil original structure is totally lost and a disoriented homogeneous and loose structure with more homogeneous pore spaces is observed (Fig. 12d).

Keywords

Clayey soils Shrink/swell Swell tests Retention curves Porosimetry Wetting–drying cycles 

Analyse du comportement d’un sol argileux sous sollicitations hydriques cycliques

Résumé

Une étude expérimentale des cycles de drainage-humidification a été réalisée sur les Argiles vertes de Romainville du bassin de Paris, afin de caractériser leur aptitude au retrait-gonflement par l’analyse de courbes de rétention, par la mesure de paramètres mécaniques (pression et taux de gonflement), et par une étude microstructurale (MEB, porosimétrie). Les résultats expérimentaux montrent que les déformations volumiques les plus grandes se produisent dans le domaine où le potentiel de l’eau est inférieur à 15 MPa, avec des valeurs de pression et de taux de gonflement élevées. Par ailleurs, au cours des cycles successifs de sollicitations hydriques, alors que les échantillons présentent une augmentation du taux de gonflement cumulé, une stabilisation des déformations de gonflement s’amorce à partir du troisième cycle, en rapport avec une réorganisation de la microstructure du sol mise en évidence par l’analyse microstructurale. Enfin, l’étude menée sur la prévision du taux et de la pression de gonflement montre que les modèles de prévision ne sont pas systématiquement applicables à tous les sols.

Mots clés

Sols argileux Retrait-gonflement Essais de gonflement Courbes de rétention Porosimétrie Cycles drainage-humidification 

Notes

Remerciements

Ces travaux ont été réalisés dans le cadre du projet de recherche: « Aléa et risque sécheresse » soutenu par la Fondation MAIF, du projet ARGIC: « Analyse du retrait–gonflement et de ses incidences sur les constructions » soutenu par l’ANR et de la fiche recherche « Sécheresse géotechnique et bâti » du R2DS (Réseau de Recherche sur le Développement Soutenable), soutenu par la région Ile-de-France.

Références

  1. AFNOR (1995) Sols, Reconnaissance et essais—Essai de gonflement à l’oedomètre—Détermination des déformations par chargement de plusieurs éprouvettes. Normalisation française, XP P 94-091, 13pGoogle Scholar
  2. Al-Homoud AS, Basma AA, Malkawi AIH (1995) Cyclic swelling behaviour of clays. J Geotech Eng 121(7):562–565CrossRefGoogle Scholar
  3. Al-Mukhtar M, Belanteur N, Tessier D, Vanapalli SK (1996) The fabric of a clay soil under controlled mechanical and hydraulic stress states. Appl Clay Sci 11:99–115CrossRefGoogle Scholar
  4. Arnould M, Audiguier M, Delage P, Pellerin F-M, Struillou R, Vayssade B (1980) Etude des sols argileux par la porosimétrie au mercure. Contrôle des variations de texture sous diverses conditions. Bull Int Assoc Eng Geol 22:213–223Google Scholar
  5. ASTM (1986) Standard test methods for one-dimensional swell or settlement potential of cohesive soils, ASTM D 4546–85Google Scholar
  6. Audiguier M, Geremew Z, Laribi S, Cojean R (2007) Caractérisation au laboratoire de la sensibilité au retrait-gonflement des sols argileux. Revue Française de Géotech 120–121:67–82Google Scholar
  7. Basma AA, Al-Homoud AS, Malkawi AH (1995) Laboratory assessment of swelling pressure of expansive soils. Appl Clay Sci 9:355–368CrossRefGoogle Scholar
  8. Basma AA, Al-Homoud AS, Malkawi AIH, Al-Bashabsheh MA (1996) Swelling–shrinkage behavior of natural expansive clays. Appl Clay Sci 11:211–227CrossRefGoogle Scholar
  9. CEBTP (1991) Détermination des solutions adaptées à la réparation des désordres des bâtiments provoqués par la sécheresse. Guide pratique CEBTP sous l’égide de l’AQC, l’APSAD, l’AFAC, la CCR et la FNB, 3 fasciculesGoogle Scholar
  10. Chassagneux D, Stieljes L, Mouroux P, avec la coll. de Ducreux GH (1995) Cartographie de l’aléa retrait-gonflement des sols (sécheresse/pluie) dans la région de Manosque (Alpes de Haute-Provence). Échelle communale et départementale. Approche méthodologique. Rapport BRGM R 38695, 90pGoogle Scholar
  11. Chen FH, Ma GS (1987) Swelling and shrinkage behaviour of expansive clays. In: Sixth international conference expansive soils, New Delhi, pp 127–129Google Scholar
  12. Day RW (1994) Swell–shrink behaviour of compacted clay. J Geotech Eng 120(3):618–623CrossRefGoogle Scholar
  13. Day RW (1995) Ultimate density of a compacted clay subjected to cycles of wetting and drying. Environ Eng Geosci 1(2):229–232Google Scholar
  14. Dif AE, Bluemel WF (1991) Expansive soils under cyclic drying and wetting. Geotech Test J 14(1):96–102CrossRefGoogle Scholar
  15. Donsimoni M, Clozier L, Motteau M, Vincent M (2003) Cartographie de l’aléa retrait—gonflement des sols argileux dans le département du Val-de-Marne. BRGM/RP-52224-FR, 136pGoogle Scholar
  16. Donsimoni M, Hatton C, Giraud F, Vincent M (2004) Cartographie de l’aléa retrait–gonflement des sols argileux dans le département du Val d’Oise. BRGM/RP-52598-FR, 170pGoogle Scholar
  17. El-Sohby MA, Rabba EA (1981) Some factors affecting swelling of clayey soils. Geotech Eng 12:19–39Google Scholar
  18. Fleureau JM, Kheirbek-Saoud S, Soemitro R, Taibi S (1993) Behaviour of clayey soils on drying–wetting paths. Can Geotech 30:287–296CrossRefGoogle Scholar
  19. Gromko GJ (1974) Review of expansive soils. J Geotech Eng Div 100(GTG):667–687Google Scholar
  20. Holtz WG, Gibbs HJ (1954) Engineering properties of expansive clays. In: Proceeding of ASCE Vol. 80, Separate No. 516Google Scholar
  21. Komine H, Ogata N (1992) Swelling characteristics of compacted bentonite. In: Proceedings of 7th international conference on expansive soils 1:216–221Google Scholar
  22. Komine H, Ogata N (1994) Experimental study on swelling characteristics of compacted bentonite. Can Geotech J 31:478–490CrossRefGoogle Scholar
  23. Komine H, Ogata N (1996) Prediction for swelling characteristics of compacted bentonite. Can Geotech J 33(1):11–22CrossRefGoogle Scholar
  24. Komornik A, David D (1969) Prediction of swelling pressure of clays. Proc ASCE, J Soil Mech Found Div 95(SM1):209–225Google Scholar
  25. Parcevaux P (1980) Etude microscopique et macroscopique du gonflement de sols argileux. Thèse doctorat, Université Paris VI, Ecole Nationale Supérieure des mines de ParisGoogle Scholar
  26. Pomerol Ch, Feugueur L (1986) Guides Géologiques Régionaux, Bassin de Paris, 3rd edn. Masson, ParisGoogle Scholar
  27. Seed HB, Woodward RJ Jr, Lundgren R (1962) Prediction of swelling potential for compacted clays. J Soil Mech Found Div ASCE 88:53–87Google Scholar
  28. Serratrice JF, Soyez B (1996) Les essais de gonflement. Bull Labo P et C 204:65–85Google Scholar
  29. Sridharan A, Rao AS, Sivapullaiah PV (1986) Swelling pressure of clays. Geotech Test J GTJODJ 9(1):24–33CrossRefGoogle Scholar
  30. Subba Rao KS, Satyadas GG (1987) Swelling potential with cycles of swelling and partial shrinkage. In: Sixth international conference expansive soils, New Delhi, pp 137–142Google Scholar
  31. Tripathy S, Subba Rao KS, Fredlund D (2002) Water content-void ratio swell–shrink paths of compacted expansive soils. Can Geotech J 39:938–959CrossRefGoogle Scholar
  32. Vincent M (2003) Retrait-gonflement des sols argileux: méthode cartographique d’évaluation de l’aléa en vue de l’établissement de PPR. 3ème conférence SIRNAT-Forum des journées pour la Prévention des Risques Naturels, Orléans, janv. 2003Google Scholar
  33. Vincent M, Bouchut J, Fleureau J-M, Masrouri F, Oppenheim E, Heck J-V, Ruaux N, Le Roy S, Dubus I, Surdyk N (2006) Étude des mécanismes de déclenchement du phénomène de retrait-gonflement des sols argileux et de ses interactions avec le bâti—rapport final. BRGM/RP-54862-FR, 378 pGoogle Scholar
  34. Yong RN, Warkentin BP (1975) Soil properties and behaviour. Elsevier, Amsterdam, pp 197–222Google Scholar
  35. Zein AKM (1987) Comparison of measured and predicted swelling behaviour of a compacted black cotton soil. In: Sixth international conference on expansive soils, New Delhi, pp 121–126Google Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Geremew Zemenu
    • 1
  • Audiguier Martine
    • 1
  • Cojean Roger
    • 1
  1. 1.Mines ParisTech, Centre de GéosciencesFontainebleauFrance

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