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Geomechanics and Engineering
  Volume 32, Number 1, January10 2023 , pages 49-68
DOI: https://doi.org/10.12989/gae.2023.32.1.049
 


A new extended Mohr-Coulomb criterion in the space of three-dimensional stresses on the in-situ rock
Mohatsim Mahetaji, Jwngsar Brahma and Rakesh Kumar Vij

 
Abstract
    The three-dimensional failure criterion is essential for maintaining wellbore stability and sand production problem. The convenient factor for a stable wellbore is mud weight and borehole orientation, i.e., mud window design and selection of borehole trajectory. This study proposes a new three-dimensional failure criterion with linear relation of three in-situ principal stresses. The number of failure criteria executed to understand the phenomenon of rock failure under in-situ stresses is the Mohr-Coulomb criterion, Hoek-Brown criterion, Mogi-Coulomb criterion, and many more. A new failure criterion is the extended Mohr-Coulomb failure criterion with the influence of intermediate principal stress (o2). The influence of intermediate principal stress is considered as a weighting of (o2) on the mean effective stress. The triaxial compression test data for eleven rock types are taken from the literature for calibration of material constant and validation of failure prediction. The predictions on rock samples using new criteria are the best fit with the triaxial compression test data points. Here, Drucker-Prager and the Mogi-Coulomb criterion are also implemented to predict the failure for eleven different rock types. It has been observed that the Drucker-Prager criterion gave over prediction of rock failure. On the contrary, the Mogi-Coulomb criterion gave an equally good prediction of rock failure as our proposed new 3D failure criterion. Based on the yield surface of a new 3D linear criterion it gave the safest prediction for the failure of the rock. A new linear failure criterion is recommended for the unique solution as a linear relation of the principal stresses rather than the dual solution by the Mogi-Coulomb criterion.
 
Key Words
    3D failure criterion; extended Mohr-Coulomb; geomechanics; in-situ stresses; triaxial principal stresses
 
Address
Mohatsim Mahetaji and Rakesh Kumar Vij: Department of Petroleum Engineering, School of Energy Technology, Pandit Deendayal Energy University- PDEU,
Gandhinagar, Gujarat, India
Jwngsar Brahma: School of Technology, Pandit Deendayal Energy University- PDEU, Gandhinagar, Gujarat, India
 

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