Abstract: The connectivity ratio significantly influences the mechanical properties and failure mechanisms of rock samples with structural planes of varying inclinations. Consequently, jointed rock samples with connectivity values k of 0, 0.25, 0.50, and 1.00, and dip angles β  of 15°, 30°, 45°, and 60° were manually prepared. Uniaxial and triaxial compression tests at confining pressures of 200, 400, and 600 kPa were conducted to investigate the effects of connectivity and dip angles on the mechanical properties of the rock mass. The results show that: 1) Connectivity significantly reduces the strength of the rock mass; peak strength decreases as connectivity increases. Stress-strain curves exhibit initial strain hardening followed by strain softening when k≤0.50; for k>0.50, the behavior transitions from strain softening at low angles to strain hardening at high angles. 2) Samples with structural planes initially shrink and then expand; overall expansion decreases with increasing connectivity at each dip angle; abrupt changes occur during shrinkage when k=1.00 at dip angles of 30°, 45°, and 60°. 3) Before energy inflection point α , dissipative energy U_d increases with connectivity while elastic strain energy U_e  slightly decreases; after point α , andU_e  both increase sharply, and different connectivity levels exhibit similar energy release rates. 4) The prediction criteria for rock samples with varying connectivity rates are classified. When k < 0.5, β=45°+φ_j /2 , it is suitable for judging the failure angle, where φ_j  is the friction angle of the structural plane; when k ≥0.5, the Jaeger criterion accurately reflects the failure angle of the rock mass.

Key words: triaxial test, mechanical properties, connectivity rate, energy method