The Tensile Strength of Compacted Clays as Affected by Suction and Soil Structure

Cui

et al. 2010

Engineering Geology

260

When drying a clayey soil, shrinkage and then cracking on soil surface occur due to water loss by evaporation, this phenomenon seems to be temperature dependent. In the present work, experimental tests were conducted on saturated slurry to investigate the desiccation cracking behavior at three temperatures (22, 60 and 105 °C). The initiation and propagation of desiccation cracks during drying was monitored using a digital camera. By applying computer image processing technique, the surface crack ratio (R SC ) which is the ratio of the surface area of cracks to the total surface area of specimen, was defined to quantify crack networks at different water contents. The experimental results show that the initial critical water content (w IC ), which corresponds to the initiation of desiccation crack, increases with temperature rise. After the initiation of a crack, the ratio R SC increases with decreasing water content and then keeps almost constant when the water content becomes lower than the critical water content (w FC ). By comparing the cracking curve with shrinkage curve, it has been found that the cracking curve, to some extent, reflects the shrinkage properties of soil since the w FC is related to the shrinkage limit and slightly influenced by temperature.

Section: Initiation Of Desiccation Crackmentioning

confidence: 99%

Experiment evidence on the temperature dependence of desiccation cracking behavior of clayey soils

Cui

et al. 2010

Engineering Geology

260

“…compression) such that the specimen fails in tension. Direct tests include modification of triaxial testing apparatus (Tang and Graham, 2000;Heibrock et al,2005;Zeh and Witt, 2007) and modification of direct shear testing apparatus (Nahlawi et al, 2004;Tamrakar et al, 2005;Trabelsi et al, 2012). Indirect tests include the Brazilian tensile test (Frydman, 1964;Krishnayya and Einsenstein, 1974), Hollow Cylinder Triaxial test (Alsayed, 2002) and beam bending (Thusyanthan et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…The preparation of beam bending specimens is relatively simple; however, results are sensitive to specimen and loading geometry in addition to strain rate. Modification of a standard triaxial testing system, such as that by Zeh and Witt (2007), requires complex specimen preparation in which a textile fabric drain is placed down the centre of the specimen, risking damage in the process. Direct testing of rectangular, bow tie or dog bone shaped prisms involves less complex specimen preparation but there is the potential for squeezing of low stiffness material by shear keys and loading jaws leading to uneven stress distributions and inaccurate measurement.…”

Section: Introductionmentioning

confidence: 99%

Tensile behaviour of unsaturated compacted clay soils — A direct assessment method

Stirling

Hughes

Davie

et al. 2015

Applied Clay Science

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThis paper presents a new method for testing the behaviour of soils placed under tensile load and demonstrates its suitability for testing a number of soil types under various conditions including saturation, compaction and stabilisation. Validation of the results obtained for the soils at relatively low saturation has been conducted using the established Brazilian (indirect) test for measuring the tensile strength of brittle materials. A fair comparison has been found and the results highlight the limited applicability of the Brazilian method to soils at very low water contents at which the tensile failure criterion has been assumed using this methodology. Optical characterisation of the performance of both testing methods has also been conducted using Digital Image Correlation. The consistent, accurate measurement of directly induced tensile strains using the proposed new method has been confirmed, verifying its capability to apply a direct tensile stress in the absence of shearing, a problem commonly associated with other tensile testing methods. The developed technique has then been used to investigate the water content -tensile strength relationship for compacted, unsaturated soils and offers significant advantages in the characterisation of clay soils subjected to variable climatic loading.

Unsaturated Soils: Research &Amp; Applications

“…These can be separated into two categories, direct and indirect tests. Direct tests include modification of triaxial testing apparatus (Tang and Graham, 2000;Heibrock et al, 2003;Witt and Zeh, 2007) and modification of direct shear testing apparatus Tamrakar et al, 2005;Trabelsi et al, 2012). Indirect tests include the Brazilian tensile test (Frydman, 1964;Krishnayya and Eisenstein, 1974) & Hollow Cylinder Triaixial test (Alsayed, 2002).…”

Section: Introductionmentioning

confidence: 99%

Cyclic relationship between saturation and tensile strength in the near-surface zone of infrastructure embankments

Stirling¹,

Hughes²,

Davie³

et al. 2014