Capturing snapback in indirect tensile testing using AUSBIT - Adelaide University Snap-Back Indirect Tensile test

Verma, Rupesh Kumar; Nguyen, Giang D.; Karakus, Murat; Taheri, Abbas

doi:10.1016/j.ijrmms.2021.104897

Cited by 12 publications

(8 citation statements)

References 60 publications

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“…12,42 The input parameters (strength, elastic and fracture properties of rock, i.e., Bluestone, in this study) for these numerical simulations were derived from the laboratory experiments, including lateral strain-controlled uniaxial compression tests and in-house AUSBIT (Adelaide University Snapback Indirect Tensile Strength Test). 43,44 Section 4 presents the detailed numerical results, verifying the applications of the proposed burst envelope in analysing burst failure. Section 5 proposes a new 'Strain burst index (₽)', enabling the quantification of the burst magnitude.…”

Section: Introductionmentioning

confidence: 71%

A size‐dependent energy‐based strain burst criterion

Verma,

Nguyen,

Karakus

et al. 2024

Num Anal Meth Geomechanics

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This paper presents a size‐dependent energy‐based strain burst criterion linking strength, elasticity, fracture energies and specimen size effect with stress state due to changes in boundary conditions. It proposes the concept of a ‘Burst Envelope’, a surface in three‐dimensional principal stress space derived based on energy storing and dissipation characteristics of a rock sample, taking into account the size of the specimen and potential localised failure pattern. A scalar burst index is also proposed to quantify the bursting scale. To illustrate and verify its functioning, a numerical modelling framework based on the distinct element method and employing a new cohesive‐frictional contact model is used to perform virtual strain burst experiments under different polyaxial loading‐unloading scenarios, mimicking various underground excavation scenarios. The obtained results are in good agreement with the theoretical prediction of burst occurrence. On that basis, the variation of burst possibility and magnitude are investigated with key factors, including confinement level and the material's elastic, strength and fracture properties. The effect of the specimen's aspect ratio and size on the rock burst potential is elaborated and verified using virtual strain burst experiments, facilitating the linking of the proposed theoretical framework with the evaluation of in‐situ strain bursts in rock masses around underground openings.

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Section: Introductionmentioning

confidence: 71%

A size‐dependent energy‐based strain burst criterion

Verma,

Nguyen,

Karakus

et al. 2024

Num Anal Meth Geomechanics

Self Cite

View full text Add to dashboard Cite

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“…The bottom platen was fixed, and the top platen moved with the pre-defined loading scenario to compress the disc specimen diametrically. This load application is collaborated with the Digital Image Correlation (DIC) technique, i.e., a non-contact and non-destructive method to obtain the full-field strain evolution [13,14,15,16]. The disc specimens were exposed to the randomly distributed black speckles on a white background to allow the image correlation.…”

Section: Experiments Setupmentioning

confidence: 99%

“…The AUSBIT applies the lateral displacement control to stabilise the sudden cracking of the disc specimens. The application of the AUSBIT aims to obtain the snap-back response for the strain analysis of the post-peak behaviour [16]. The vertical deformation of the disc specimen was continuously adjusted to maintain a pre-defined constant lateral deformation rate of 0.5 μm/min.…”

Section: Experiments Setupmentioning

confidence: 99%

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Effect of layer orientation on behaviour of 3D-printed rock specimens in indirect tensile testing

Yang

Huang

Verma

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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The mineralogical composition, texture and fracture of natural rocks can be complicated due to the inherent heterogeneity of geomechanical properties, making it challenging to understand their behaviour. Due to the intrinsic layer by layer manufacturing process, 3D printing technology enables to create rock-like materials and specimens with known and controllable inhomogeneity. In this study, disc specimens of a rock-like material are fabricated using 3D printing of cement mortar for testing to understand fabric orientation effect on fracture behaviour better. For the first time, a novel technique, named AUSBIT (Adelaide University Snap-back Indirect Tensile test), for Brazilian disc tests is applied for obtaining both strength and snap-back post-peak behaviour of the 3D printed rock-like materials. Adopting Digital Image Correlation (DIC) technique, in conjunction with the use of AUSBIT, allows obtaining full-field strains and their evolutions, showing strong effects of fabric orientation on strain distributions and both pre-and post-peak responses.

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“…Cook and Ortlepp initially proposed the concept of yielding support in South Africa's deep gold mines (Cai et al 2010). Since then, various dynamic bolt designs such as Conebolts, Modified Conebolts, Durabar, Duracable, MCB33, Roofex, Garford bar, D-bolts, He bolts, Dynamic Omega bolts and Dyna Rock bolts have emerged in the market (Bayati et al 2021;Fuławka et al 2023;Chen & Li 2015;Kaiser & Moss 2022;Cai 2013;Verma et al 2021). However, the mechanical performance of existing bolt designs still needs to be improved to better withstand the substantial rock deformations encountered in ultra-deep mining.…”

Section: Introductionmentioning

confidence: 99%

Dynamic impact and static testing of self-drilling dynamic bolt types installed in Normet’s urea-silicate injection resin: a new path forward to reducing worker exposure to high-stress ground conditions

Punkkinen,

Li,

Taheri

2023

Ground Support 2023: Proceedings of the 10th International Conference on Ground Support in Mining

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In deep mining operations, large deformation of surrounding rock and rockbursts have become unavoidable concerns worldwide, exposing workers to high-stress hazards. In response to these challenges, Normet has developed high-energy dissipation self-drilling dynamic bolt (SDDB®) varieties installed in urea-silicate injection resin. This research evaluates the static and dynamic performance of Normet's fully encapsulated SDDB. To enable a comprehensive evaluation, an innovative test method utilising continuous and split tube configurations was developed to assess the installation of fully encapsulated bolts in both intact surrounding rock and jointed rock mass. The tests included pull tests, shear tests, continuous tube drop tests and split tube drop tests. Static tests provided insights into the yield load, maximum load, failure load, and bolt elongation under tensile and shear stress, while the dynamic tests evaluated the performance of the SDDB during impact and characterised the failure patterns of the bolts. The fully encapsulated Leinster SDDB exhibited a maximum load capacity of 349.8 kN with 80 mm elongation in the pull test. In comparison, the Onaping SDDB withstood a shear load of 282.6 kN and generated a displacement of 27 mm. Furthermore, the Nevada and Nordic coupled SDDB demonstrated a total elongation of 196 mm and withstood an impact load of 271 kN in the drop test. These research findings highlight the exceptional mechanical properties of Normet's SDDB and its efficacy as a dynamic ground support component in high-stress environments.

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Capturing snapback in indirect tensile testing using AUSBIT - Adelaide University Snap-Back Indirect Tensile test

Cited by 12 publications

References 60 publications

A size‐dependent energy‐based strain burst criterion

A size‐dependent energy‐based strain burst criterion

Effect of layer orientation on behaviour of 3D-printed rock specimens in indirect tensile testing

Dynamic impact and static testing of self-drilling dynamic bolt types installed in Normet’s urea-silicate injection resin: a new path forward to reducing worker exposure to high-stress ground conditions

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