Direct and Indirect Tensile Tests for Measuring the Equivalent Effective Stress in a Kaolinite Clay

Vesga, L. F.; Vallejo, Luis E.

doi:10.1061/40802(189)106

Cited by 16 publications

(5 citation statements)

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“…The Brazilian tensile strength test is commonly used to measure the tensile strength of rock and concrete specimens (Sundaram and Corrales 1980;Chen et al 1998;Nazir et al 2013). This method was advanced to measure the tensile strength in soils by Vesga and Vallejo (2006) and Li et al (2015). A set of tests was run to assess the tensile strength of the fine-grained soils at different degrees of saturation.…”

Section: Brazilian Tensile Strength Testmentioning

confidence: 99%

Shear strength and stiffness behavior of fine-grained soils at different surface hydration conditions

Jeong-Ki¹,

Fratta

Akin

2022

Can. Geotech. J.

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We developed an experimental program to monitor how interparticle forces control fine-grained soils' mechanical behavior when saturation changes from the tightly adsorbed regime to saturation. The testing program uses stiffness (i.e., S-wave velocity) and strength (i.e., Brazilian tensile strength) tests on kaolinite, silica flour, and diatomaceous earth soil samples at very low confining stresses (< 5 kPa). Three fine-grained soils yield a range of different properties, including particle size, specific surface area, negative charge density, and internal/external particle porosity. Results show that shear stiffness and tensile strength follow similar trends, emphasizing that the same interparticle forces control the mechanical responses. In particular, the interpretation of S-wave velocity measurements shows three different behavior ranges: a van der Waals attraction range, a capillary-dominated interparticle forces range, and the continuous decrease in the capillary forces from the saturation at the air-entry pressure until full saturation. We show that the interparticle forces respond to a complex function of water content, particle size, particle separations, surface charge density, and the presence of internal particle porosity.

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Section: Brazilian Tensile Strength Testmentioning

confidence: 99%

Shear strength and stiffness behavior of fine-grained soils at different surface hydration conditions

Jeong-Ki¹,

Fratta

Akin

2022

Can. Geotech. J.

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“…The Brazilian tensile strength (BTS) test is an indirect tensile test originally developed for rock (ASTM D3967-16 ) but has been used to obtain the tensile strength of soils (e.g., Khrishnayya and Eisenstein 1974, Das et al 1995, Vesga and Vallejo 2006, De Souza Villar et al 2009, Beckett et al 2015, Iravanian and Bilsel 2016, Akin and Likos 2017. A review on the development of the BTS test can be found in Li and Wong (2013).…”

Section: Brazilian Tensile Strength (Bts) Testmentioning

confidence: 99%

“…Comparison between direct and indirect tensile tests show no significant differences between the tensile strength (e.g., Vesga and Vallejo 2006, Fahimifar and Malekpour 2012, Kim et al 2012.…”

Section: Introductionmentioning

confidence: 99%

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Tensile strength of unsaturated coarse and fine-grained soils

Bulolo

Leong

Kizza

2021

Bull Eng Geol Environ

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Soils at the ground surface experience multiple cycles of drying and wetting. On drying, the soils experience shrinkage and cracks may appear. The development of cracks depends on the tensile strength of the soil. Such cracks increases the permeability of the soil and can cause slopes and earth structures to fail due to rainfall. Several tensile strength models have been proposed for unsaturated soils considering the effect of matric suction. However, the tensile strength models proposed are for either cohesionless (coarse-grained) or clayey (fine-grained) soils. The tensile strength models were shown to be different in their definition of suction stress and the presence or absence of a cohesion term. As tensile strength data of fine-grained soils with the same soil structure and soil-water characteristic curve data are lacking in the literature, Brazilian tensile tests and SWCC tests were conducted on compacted fine-grained soils from two residual soil formations. The test data highlighted the problem in the friction angle used in existing tensile strength models. Using a general form of the suction stress and the extended Mohr-Coulomb criterion with the Brazilian test Mohr circle, a new tensile strength model applicable to both coarse-grained and fine-grained soils was proposed. The proposed model was shown to perform better than existing models using independent data.

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“…Preparation of rock specimen for a DTT is usually time consuming and expensive; hence this test is not usually performed in rock mechanic laboratories (Butenuth et al 1995;Coviello et al 2005;Mellor and Hawkes 1971). Nevertheless, DTT methods have been used by geotechnical researchers to investigate the tensile strength of unsaturated soils, over-consolidated clays, and cemented sands, even though sample preparation is not easy for these materials and test equipment has to be tailored to accommodate the specific soil properties (Ajaz and Parry 1974;Lu et al 2007;Vesga and Vallejo 2006).…”

Section: Introductionmentioning

confidence: 99%

Measurement of the Tensile Strength of Organic Soft Rock

2014

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Understanding all potential slope failure mechanisms is a pre-requisite for predicting the likelihood of batter movements during excavation in open cut mines. The tensile behavior of soils and rocks may be a significant contributor to a slope failure and must be known in order to quantify the risks of slope failure. The contribution can be particularly significant for Intermediate Geotechnical Materials (IGMs) that possess characteristics of both soils and rocks and where the failure mechanisms are complex due to the interplay between ductile and brittle behavior. Brown coal is such an intermediate geotechnical material. Recent batter movements in the brown coal mines in the Latrobe Valley, Australia have raised doubts about the current understanding of the mechanisms of slope failure in this material.Research is underway to re-evaluate all properties of the brown coal applicable to slope failure. This paper describes the investigation of brown coal tensile strength. There are alternative test methods available to determine the tensile behavior of materials, including direct tensile tests, beam bending tests and Brazilian compression tests. The applicability of each test method is material dependent and, as such, it is necessary to confirm the validity of the methods for each material. Beam bending tests have achieved mixed results for both rocks and IGMs previously. Thus, the present work has explored only the use of Direct tensile and Brazilian test methods. Both methods were implemented using a modified direct shear apparatus and valid test procedures for both test methods were developed. Each test procedure has been verified by Finite Element Modelling (FEM) using ABAQUS 6.12.1 FEM code. The results from the laboratory test methods are in good agreement and show that brown coal is a predominantly brittle material with a peak tensile strength slightly greater than 100 kPa. The finite element analyses confirm that non-uniformity of the tensile stresses during sample loading tends to lead to the underestimation of tensile strength for both tests, but the Brazilian test has less bias for brown coal. It is observed that the rate of Manuscript

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Direct and Indirect Tensile Tests for Measuring the Equivalent Effective Stress in a Kaolinite Clay

Cited by 16 publications

References 0 publications

Shear strength and stiffness behavior of fine-grained soils at different surface hydration conditions

Shear strength and stiffness behavior of fine-grained soils at different surface hydration conditions

Tensile strength of unsaturated coarse and fine-grained soils

Measurement of the Tensile Strength of Organic Soft Rock

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