Considering effect of modulus of elasticity and confining pressure on mode-I fracture toughness of chalky specimens

Document Type : Research Paper

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Abstract

There are three notch displacement modes including the Mode I or opening mode where the notch displacement is perpendicular to the notch front, Mode II or shear mode where notch dimensions are displaced in the notch plane and the Mode III or tear mode where the notch dimensions are displaced in the notch plane parallel to the notch front. Some application areas of rock fracture mechanics can be listed as hydraulic fracturing, rock blasting, rock cutting, mechanized drilling, rock slope stability and comminution in mineral processing. The aim of the present study was to examine the effect parameter of , modulus of elasticity and confining pressure on the mode I Critical Stress Intensity Factor (Critical SIF) using a thick-walled hollow cylindrical chalky specimen and the oil well environment was simulated in the laboratory. To perform the tests on artificial chalky specimens, two artificial symmetrical notches with certain dimensions were created in specimens with an outer diameter (OD) of 73 mm, an inner diameter (ID) of 25 mm and a height of 150 mm. A triaxial stress was applied on the specimen and the pressure required for the propagation of the artificial notches was measured. Five tests were conducted to investigate the effect of modulus of elasticity and six tests to investigate the effect of confining pressure on the mode I Critical SIF. By conducting five tests, it was concluded that with increasing modulus of elasticity, mode I Critical SIF increases and with increasing Poisson’s ratio mode I Critical SIF decreases, also, effect of modulus of elasticity on mode I Critical SIF is more. Meanwhile, it was found that the mode I Critical SIF nonlinearly increased with an increase in modulus of elasticity and it linearly increased with an increase in confining pressure.

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References

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History

  • Receive Date: 05 June 2016
  • Revise Date: 31 December 2016
  • Accept Date: 08 January 2017

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