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Abstract Triaxial compression tests for cracked samples under axial loading and constant confining pressure，axial loading and radial unloading，constant axial pressure and radial unloading—three stress paths were carried out by using WDT–1500 multi-function material testing machine. The deformation property，strength property and failure mechanism of cracked samples were researched. It shows that there is significant change in mechanical parameters under this three stress paths. The strength of cracked samples of axial loading and radial unloading，constant axial pressure and radial unloading were lower than that of axial loading and constant confining pressure. Under different stress paths，the strength of crack samples decreases first and then increases with the crack angle increases，and reaches minimum at crack angle of 30°or 45°. The mechanical characteristics of cracked samples are mainly related to the crack angle，the loading paths and the initial confining pressures，and the greatest influence factor is the crack angle，the intermediate is the unloading velocity of confining pressure，and the least is the initial confining pressure. The failure characteristics of samples present shear failure under axial loading and constant confining pressure，but it often presents mixed Tensile-shear failure under axial loading and radial unloading，constant axial pressure and radial unloading. Tensile-crack is less under axial loading and radial unloading，but it develops significantly under constant axial pressure and radial unloading.
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Received: 20 December 2012
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2013, Vol. 32 
