An Expanded Wing Crack Model for Fracture and Mechanical Behavior of Sandstone Under Triaxial Compression

Area of Science:

• Geotechnical Engineering
• Materials Science
• Rock Mechanics

Background:

• Predicting the mechanical behavior of brittle sandstone under triaxial compression is crucial for engineering applications.
• Existing models may not fully capture the complex crack interactions influencing rock failure.

Purpose of the Study:

• To develop a novel model for predicting the failure strength of brittle sandstone under triaxial compression.
• To estimate normalized critical crack length (L) for failure strength prediction using fracture mechanics.

Main Methods:

• Adopted the wing crack model to calculate total stress intensity at the crack tip, considering crack initiation and interaction.
• Derived the normalized critical crack length (L) and set it equal to the crack length.
• Equated total stress intensity to rock fracture toughness to estimate failure strength (σ).

Main Results:

• The proposed model accurately predicts sandstone failure strength (σ) under triaxial compression.
• Theoretical predictions showed strong agreement with laboratory data from Wyoming sandstone and published literature.
• Achieved the lowest Root Mean Square Error (RMSE) and Mean Absolute Deviation (MAD) values of 36.95 and 30.93, respectively, compared to other models.

Conclusions:

• The developed fracture mechanics-based model offers a superior method for predicting brittle sandstone failure strength.
• The model's accuracy is validated by its performance against experimental data and comparison with existing failure criteria.
• This approach enhances the understanding of crack interaction effects on rock mechanical behavior.