Abstract: By using equivalent rock mass(ERM) technique, the ERM models containing diverse joint dip angle and connectivity rate are constructed, in which the joint and rock block are represented by smooth joint model and bonded particle model, respectively. Combining with test result, the effect of joint connectivity rate on strength, fracture mechanism and energy evolution of rock mass under the condition of uniaxial compression, is quantitatively investigated from meso-mechanical viewpoint. Research shows that when an angle presents between joint and load direction, rock mass behaves as the tendency of coalescence failure along the connecting direction of rock bridge. Especially with joint dip angle α of 30° and connectivity rate L of 0.8, rock mass exhibits composite coalescence failure of rock bridge. Under the condition of the joint dip angle α of 30°, with increase of joint connectivity rate, rock mass exhibits the following mechanical behaviors: (1) The peak compressive strength continually decreases. (2) The amount of microcracks decreases, but the ratio of tensile microcracks increases. Meanwhile, microcracks gradually generate on the rock bridge line between different level joint tip. (3) The occurrence time of acoustic emission (AE) event during the entire loading stage gradually disperses. The amount of AE event as well as the distribution range, mean value and standard deviation of fracture magnitude decreases. (4) The peak strain energy as well as the post-peak change rate of strain and kinetic energy reduces. The growth of post-peak frictional energy slows down. The required work supplied by exterior to destroy the specimen reduces.

Key words: joint, connectivity rate, rock mass, mechanical properties, meso