Effects of Environment on the Performance of Shallow Foundations

Hamilton, J. J.

doi:10.1139/t69-008

Cited by 17 publications

(9 citation statements)

References 3 publications

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“…These fluctuations are usually insufficient to allow full equilibrium to be reached at any given depth. Because the stress-strain behaviour of clays is nonreversible, the measured water contents are usually dry of complete equilibrium, even after climatic cycles lasting perhaps 7-8 years which are encountered in the Canadian Interior Plains (Hamilton 1969). For similar reasons, the depth H, of seasonal changes in water content is usually less than the depth Hd to the permanent water table.…”

Section: Moisture Content and Suction Distributionsmentioning

confidence: 99%

“…The 6 m depth corresponds to the depth of atmospheric weathering and a colour change from brown near the surface to grey-blue at depth. Since the current climate produces seasonal moisture changes only to about 3-4 m depth (Hamilton 1969), the cracks to 6 m depth correspond to warmer and drier climatic conditions during the hypsothermal period 9000-4500 years ago follow-ing the draining of proglacial Lake Agassiz. Inclined fissures and slickensiding are also found in these deposits.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Cracking in drying soils

Morris¹,

Graham²,

Williams³

1992

Can. Geotech. J.

458

236

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Cracking in soils that are undergoing drying is controlled by soil suctions and by soil properties such as compression modulus, Poisson's ratio, shear strength, tensile strength, and specific surface energy. The paper reviews the occurrence and morphology of cracks in dry-climate regions of Australia and Canada. After reviewing the behaviour of unsaturated soils and the mechanics of cracking, solutions are developed based on ( i ) elasticity theory, ( i i ) the transition between tensile and shear failure, and (iii) linear elastic fracture mechanics. The solutions are compared and related to crack depths observed in the field.La fissuration dans les sols subissant une dessiccation est contr81Ce par la succion et par les propriCtCs du sol telles que le module de compression, le rapport de Poisson, la rksistance au cisaillement, la rCsistance en tension, et 1'Cnergie de la surface spkcifique. L'article passe en revue la distribution et la morphologie de fissures dans les rCgions B climat sec de 1'Australie et du Canada. Aprks avoir pass6 en revue le comportement des sols non saturts et la mCcanique de fissuration, des solutions ont Ct C dCveloppCes sur la base de ( i ) la thCorie d'ClasticitC, ( i i ) la transition entre la rupture en tension et en cisaillement, et (iii) la mCcanique de fissuration Clastique 1inCaire. Les solutions sont comparCes et relikes aux profondeurs des fissures observCes sur le terrain.

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Section: Moisture Content and Suction Distributionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cracking in drying soils

Morris¹,

Graham²,

Williams³

1992

Can. Geotech. J.

458

236

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“…Drying at the ground surface has caused considerable reductions in moisture content in the Winnipeg clay (Hamilton 1969). Extensive joint sets may extend almost vertically to the underlying till and bedrock at an average depth of around 20 m (Baracos et al 1983).…”

Section: Freeze-thaw and Softening Processes: Generalmentioning

confidence: 99%

Effects of freeze–thaw and softening on a natural clay at low stresses

Graham¹,

Au²

1985

Can. Geotech. J.

139

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Weathering processes such as softening and freeze-thaw cycling affect the properties of clays. Care must therefore be taken when selecting strength and compressibility parameters for analysis of natural slopes, compacted clay embankments, and trench excavations in which significant proportions of the cross section can be affected by climatic weathering.Samples of plastic Lake Agassiz clay from Winnipeg were consolidated anisotropically in the laboratory to axial stresses less than or equal to the in situ effective overburden pressure. They were therefore all overconsolidated with respect to the field preconsolidation pressure. The samples were then loaded under drained or undrained conditions along steeply rising stress paths in p', q stress space. One group of samples was tested immediately to identify the "undisturbed behavior, a second group was subjected to freeze-thaw cycles, and a third group allowed to swell freely before testing.The freeze-thaw cycling produced increased compressibility and pore-water pressures, and reduced strengths at low stresses compared with the behavior of undisturbed clay. Freezing also caused the development of a clearly defined fissure structure. Softening at low stresses with access to water produced less marked effects.Les processus d'altkration tels que le ramollissement et les cycles gel-dCgel affectent les propriCtCs des argiles. 11 faut donc &tre prudent lorsqu'on choisit les paramktres de rCsistance et de comprCssibilitC pour l'analyse des pentes naturelles, des remblais en argile compactCe et des excavations de tranchCes dans lesquels une proportion importante de la section peut &tre affectCe par 1'altCration climatique.Des Cchantillons d'argile plastique du lac Agassiz de Winnipeg ont Ct C consolidCs anisotropiquement au laboratoire sous des contraintes inferieures ou Cgales B la pression effective des terres. 11s Ctaient par consCquent tous surconsolidCs par rapport B leur pression de prCconsolidation. Les Cchantillons ont ensuite Ct C chargCs en condition drainCe ou non-drainCe suivant des cheminements de contraintes montant rapidement dans un espace p', q. Un groupe d'Cchantillons a Ct C test6 immkdiatement pour identifier le comportement "intact," un second groupe a Ct C soumis B des cycles gel-dCgel et un troisikme groupe a Ct C laissi: en gonflement avant essai. Les cycles gel-dCgel ont produit une augmentation de la compressibilitC et des pressions interstitielles et une diminution de la resistance sous faible contrainte, par rapport B 1'Ctat intact. Le gel a aussi produit le dCveloppement d'une structure de fissures clairement dCfinie. Le ramollissement sous faible contrainte avec accks libre de I'eau a produit des effets moins marques.

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“…3, has been approximated because elevation readings made by others between August 22, 1961 andAugust 15, 1962 were found to be unreliable. The shape of the curve has been made similar to that of a plot of heave over time for another test area in Regina (Hamilton 1969). This latter test area was flooded intentionally and showed that heaving took place almost irnmediately.…”

Section: History Of the Study Sitementioning

confidence: 68%

Prediction of total heave of a slab-on-grade floor on Regina clay

1983

International Journal of Rock Mechanics and Mining Sciences &am

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Geotechnical Journal, 20, 1, pp. 69-81, 1983 The prediction of total heave on a slab-on-grade floor on regina clay Yoshida, R. T.; Fredlund, D. G.; Hamilton, J. J. Reprinted from Canadian Canadian Geotechnical JournalThe prediction of total heave of a slab-on-grade floor on Regina clay S veral analytical methods for the prediction of total heave of desiccated, expansive soils have been proposed for various geo raphic regions. The proposed method herein is based on a general theory for unsaturated soil. The in-situ stress conditions, as a sessed from the corrected swelling pressure and the required soil moduli, are deduced from the constant volume oedometer test. iVtrification of the proposed method was accomplished using data accumulated from the m~nitoring of movements of a floor slab n a light industrial building in north-central Regina, Saskatchewan. A leak in a water line buried under the floor slab resulted in a f, aximum heave of about 106 mm. Of the three final pore-water pressure distributions assumed, the one where pressure is consbnt with depth and equal to atmospheric pressure appears to be representative of the field conditions corresponding to the max'mum measured heave. The measured heave represents 89% of the predicted heave for the zero pore-water pressure t distvbution. It is concluded that the proposed method of analysis, based upon a general theory for unsaturated soils, provides a practical method to accwately assess total heave. Plusieurs mCthodes analytiques de prkdiction du soultvement total des sols expansifs dtssCchCs ont Bt C proposkes pow diffkrentes rkgions gkographiques. La mCthode proposte ici est fondCe sur une thkorie gtnCrale des sols non saturCs. Les conditions de constraintes en place, telles que dtduites de la pression de gonflement corrigke, et les modules du sol necessaires sont ddduits d'un essai oedomktrique A volume constant.La ~Crification de la mCthode proposCe a Ct C faite A partir des donnCes accumulCes 101-5 de I'obsemation d'une dalle de plancher dans un bltiment industriel lCger dans le centre-nord du RCgina, Saskatchewan. Une fuite dans une conduite d'eau enterrCe sous cette dalle a provoquC un soultvement maximum de 106 mm. Des trois distributions finales de pression interstitielle suppodes, la pression interstitielle constante avec la profondeur et Cgale A la pression atmosphCrique semble Ctre representative des conditions du terrain correspondant au soultvement maximum. Le ...

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Effects of Environment on the Performance of Shallow Foundations

Abstract: /npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

Cited by 17 publications

References 3 publications

Cracking in drying soils

Cracking in drying soils

Effects of freeze–thaw and softening on a natural clay at low stresses

Prediction of total heave of a slab-on-grade floor on Regina clay

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