An Investigation on Failure Behaviour of a Porous Sandstone Using Single-Stage and Multi-stage True Triaxial Stress Tests

Autor: Vida Minaeian, Vamegh Rasouli, David N. Dewhurst
Rok vydání: 2020
Předmět:
Zdroj: Rock Mechanics and Rock Engineering. 53:3543-3562
ISSN: 1434-453X
0723-2632
DOI: 10.1007/s00603-020-02134-y
Popis: The deformational characteristics of a set of synthetic sandstones when subjected to true triaxial stress conditions were investigated in this study. The experimental results showed that the lateral stress anisotropy (σ2 ≠ σ3) significantly affected the rock’s compressive strength, elastic modulus, inelastic deformation, dilatancy and failure mode. By increasing the intermediate principal stress (σ2) over quasi-isotropic conditions (σ2 = σ3), the measured compressive strength increased more than twice in some cases, and the onset of dilatancy was suppressed to more than 80% of the peak stress. The obtained failure stresses were examined against a Mogi-type true triaxial criterion and indicated a good fit to the empirical model. Furthermore, multistage-true triaxial tests were carried out on the sandstones, and their results were compared against the single-stage test data to examine the suitability of this testing method for evaluation of the σ2 impact on the rock’s mechanical properties. Over the course of each multistage-true triaxial test, a sample was loaded to several levels of intermediate principal stress, while the minimum stress was held constant. Comparing the results of the multistage-true triaxial tests on the synthetic sandstones with the equivalent single-stage true triaxial measurements revealed noticeable differences between the resultant rock strengths and elastic properties. The findings of these tests are discussed and the potential mechanisms responsible for the observed disagreements are explained in this paper.
Databáze: OpenAIRE
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