Crack Initiation and Propagation of Clays Under Indirect Tensile Strength Test by Bending Related to the Initial Suction

Ameur, Lamine Ighil; Hattab, Mahdia

doi:10.1007/978-3-319-52773-4_19

Cited by 3 publications

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“…The tests aim to understand the shrinkage mechanisms, to study the conditions that lead to the appearance of drying cracks, as well as to follow the cracked network in the soil from different parameters such as: the water content, the total crack area, the average crack width, the number of segments and crack rate. [ 8–23 ] In these studies, various laboratory techniques have been used to describe the soil strains variations during the drying process, from shrinkage to initiation and propagation of cracking. Let us mention below the digital image correlation (DIC) technique and the extensometry technique.…”

Section: Introductionmentioning

confidence: 99%

“…While in the presence of shear stresses in the vicinity of the crack, this direction tends to follow the maximum principal mechanical strain ahead of the crack tip. Thereafter, Ighil Ameur and Hattab [23] combined the DIC technique with an experimental indirect bending tensile device on an industrial kaolinite beams of 35 × 10 × 10 mm 3 initially submitted to different suction levels (361, 110 and 38 MPa). They showed for all cases that critical strain was reached when the stress reaches the maximum tensile strength of the beam, itself depending on the initial suction.…”

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Shrinkage cracking of unsaturated fine soils: New experimental device and measurement techniques

Hajjar

Ouahbi

Eid

et al. 2020

Strain

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Clay fine soils are characterised by an ability to change volume when subjected to suction. Soil cracking due to desiccation is a phenomenon of great importance in the environmental geotechnical engineering domain. Aiming to understand shrinkage mechanism, and conditions that lead to appearance of drying cracks, a new experimental testing coupled device digital image correlation-clay ring test (DIC-CRT) was developed to investigate fine soils shrinkage and cracking. The new feature of this paper is to link both measurement techniques, based on 2D/3D-DIC and an innovative CRT, in order to assess stress and strain in soils during desiccation. Tests were carried out on a kaolinite having a liquid limit of w L = 40%, and prepared as a slurry with w = 1.5 w L of water content. The results highlight the relevance in combining these two techniques, particularly to assess internal stresses developed in the material using CRT and link them to strains leading to cracking measured by DIC method. K E Y W O R D S clay ring test, digital image correlation, kaolinite, shrinkage cracking, soil strain, strain gages 1 | INTRODUCTION From geotechnical point of view, the suction increases in the soil, due to the evaporation which causes a gradual loss of water. Clay fine soils are characterised by their ability to volume change when subjected to high suction. [1-3] This results in a shrinkage settlement and sometimes in cracks opening on the soil surface. Cracking phenomenon accelerates further the phenomenon of evaporation on the soil's surface by exposing the soil in depth to climatic effects, which create new evaporation through the cracks surfaces. Thus, evaporation is no longer only along the surface of the soil, but also through the surfaces created by cracking. [4] These effects lead to changes in the thermal, hydraulic and mechanical properties, particularly in terms of hydraulic conductivity and its water retention capacity. [5-7] Shrinkage and cracking phenomenon studies have been studied in the literature on clay materials. The tests aim to understand the shrinkage mechanisms, to study the conditions that lead to the appearance of drying cracks, as well as to follow the cracked network in the soil from different parameters such as: the water content, the total crack area, the average crack width, the number of segments and crack rate. [8-23] In these studies, various laboratory techniques have been used to describe the soil strains variations during the drying process, from shrinkage to initiation and propagation of cracking. Let us mention below the digital image correlation (DIC) technique and the extensometry technique.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%