Modeling Splitting and Spalling of Columnar Ice Compressed Biaxially: The Role of Crack Nucleation

Kolari, Kari

doi:10.1029/2018jb017032

Cited by 4 publications

(1 citation statement)

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“…7b. This process also occurs in less granular materials like ice and is geometrically somewhat more complicated in 3D, (Kolari 2019). In a vertical borehole, the equibiaxial stress, which increases with depth, drives the core through the same sequence of C CC and the stress thresholds C CI , C CD , and C P as in uniaxial compression.…”

Section: Progressive Brittle Failure In Multiaxial Loadingmentioning

confidence: 99%

An Extension Strain Type Mohr–Coulomb Criterion

Staat

2021

Rock Mech Rock Eng

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Extension fractures are typical for the deformation under low or no confining pressure. They can be explained by a phenomenological extension strain failure criterion. In the past, a simple empirical criterion for fracture initiation in brittle rock has been developed. In this article, it is shown that the simple extension strain criterion makes unrealistic strength predictions in biaxial compression and tension. To overcome this major limitation, a new extension strain criterion is proposed by adding a weighted principal shear component to the simple criterion. The shear weight is chosen, such that the enriched extension strain criterion represents the same failure surface as the Mohr–Coulomb (MC) criterion. Thus, the MC criterion has been derived as an extension strain criterion predicting extension failure modes, which are unexpected in the classical understanding of the failure of cohesive-frictional materials. In progressive damage of rock, the most likely fracture direction is orthogonal to the maximum extension strain leading to dilatancy. The enriched extension strain criterion is proposed as a threshold surface for crack initiation CI and crack damage CD and as a failure surface at peak stress CP. Different from compressive loading, tensile loading requires only a limited number of critical cracks to cause failure. Therefore, for tensile stresses, the failure criteria must be modified somehow, possibly by a cut-off corresponding to the CI stress. Examples show that the enriched extension strain criterion predicts much lower volumes of damaged rock mass compared to the simple extension strain criterion.

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Section: Progressive Brittle Failure In Multiaxial Loadingmentioning

confidence: 99%