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Abstract Triaxial loading and unloading tests were carried out on prefabricated cylindrical rock samples with non- interpenetrated joints at three different joint connectivities. The stress-strain curves，the failure mechanism and the strength characteristics of the specimens during loading and unloading under the three test conditions were compared. The relationships between the characteristics of deformation and strength and the joint connectivity were also analyzed. The results show：(1) The rock samples with non-interpenetrated joints exhibit anisotropic mechanical properties during loading or unloading conditions. An increase in joint connectivity leads to an increase in the degree of anisotropy；(2) The unloading process produces more cracks and hence greater extent of damage in the specimen；(3) The joint connectivity has significant influence on the deformation behaviour of the specimens at the unloading stage. The deformation modulus decreases gradually as the joint connectivity increases；(4) For different joint orientations，the decrease in deformation modulus of rocks with non-penetrated joints at the unloading stage has a linear relationship with the joint connectivity；(5) As the joint connectivity increases，the peak strength of the specimen at the loading stage decreases and，at the unloading stage，its cohesion and internal friction angle also decrease.
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2015, Vol. 34 
