Mechanical Properties and Failure Patterns of Double-fracture Sandstones With Different Configurations
In this paper,two sand-like samples of prefabricated fractures are made from similar materials.The effects of different fracture con-figurations and fracture angles on the mechanical characteristics and failure modes of rock samples are studied by uniaxial compression and dig-ital image processing(DIC)imaging.The results show that,the peak strength of the samples with different fracture configurations is related to the fracture inclination.When the fracture inclination is(α≤30°),the peak strength of the samples with coplanar double fracture is the lar-gest,followed by echelon fracture,and X-shaped cross fracture is the smallest.The maximum elastic modulus is obtained at the coplanar double crack and the minimum value is obtained at the en echelon crack.The damage of coplanar double crack and X-shaped cross crack is mainly tensile failure,while the mixed damage of tension and shear occurs in en echelon crack.The peak strength of en echelon fracture speci-mens is the highest at fracture inclination(α≥45°),followed by coplanar double fracture,and X-shaped cross fracture is the smallest.The minimum values of the elastic modulus are obtained at the X-shaped cross crack.Both coplanar double fracture and en echelon fracture sam-ples occur tensile shear failure,while X-shaped cross fracture occurs tensile failure.When the crack inclination is 90°,the peak stress of X-shaped cross crack is the largest.
Dip angle of fractureUniaxial compressionDifferent configurationsMechanical property
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