| Autor: |
Huang, Da, Liu, Yang, Cen, Duofeng, Peng, Jianbing, Zeng, Bin |
| Předmět: |
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| Zdroj: |
Rock Mechanics & Rock Engineering; Jan2023, Vol. 56 Issue 1, p143-166, 24p |
| Abstrakt: |
Rock fractures often occur in the coexisting compressive–tensile stress state. However, the influencing rules of compressive stress on the tensile strength and fracture behaviour under the condition of confined direct tension are still unclear. In this study, with the help of auxiliary equipment installed in a triaxial compressive cell, confined direct tensile tests (CDTTs) on granite samples were carried out to explore the impacts of confining pressure (0–12 MPa) and loading rate (0.005–0.03 mm/s) on the tensile strength, fracture and energy conversion. The test results suggest that when the confining pressure increases from 0 to 6 MPa, the average tensile strength first increases by 18.51%. When the confining pressure increases from 6 to 12 MPa, the average tensile strength then decreases by 24.85%. As the confining pressure increases, the failure patterns of the granite samples under CDTTs present a transition from tensile failure to mixed tensile–shear failure. Based on the analysis of the micro-damage and fracture caused by the interaction forces among grains of crystalline rock, the influencing mechanism of confining pressure and loading rate on the tensile strength and fracture surface roughness as well as energy conversion of granite under a CDTT are discussed. The perspective is proposed that the increased confining pressure can change tensile fracture to mixed fracture at the macro-scale, but the increased tensile loading rate can only transform tensile intergranular to tensile trans-crystalline fracture at the micro-scale. Highlights: With the help of auxiliary equipment installed in a triaxial compressive cell, confined direct tensile tests (CDTTs) of cylindrical granite samples were carried out under different confining pressures and loading rates. The influences of confining pressure and loading rate on the failure patterns, roughness of fracture surfaces, tensile strength and deformation characteristics of granite samples under CDTTs were studied. The energy composition and calculation method of the granite samples under CDTTs were introduced in detail, and the impacts of confining pressure and loading rate on the total energy, elastic energy and dissipated energy were analysed. The influencing mechanism of confining pressure and loading rate on the tensile strength and fracture surface roughness as well as energy conversion of granite under a CDTT are discussed. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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