Popovic R.,Mining and Metallurgy Institute of Bor |
Ljubojev M.,Mining and Metallurgy Institute of Bor |
Ignjatovic D.,Mining and Metallurgy Institute of Bor |
Ljubojev V.,Mining and Metallurgy Institute of Bor |
Ignjatovic L.D.,Mining and Metallurgy Institute of Bor
Technics Technologies Education Management | Year: 2010
The paper presents theoretical basis of the fracturing on aspect of geo-mechanic and laboratory confirmed experiments by the complex state of stress. Experiments were performed in the laboratory on samples of rock, with relations of h/d = 1,5 and diameter d=54[mm] in triaxial cell. The main stress σ 1 acts along the axis of the tested sample, and the other two stresses are directed normal to the axis of the cylinder. It is clear that the character of fracture is under heavy influence of lateral pressure σ 3. If σ 3 is small, up to 20 [MPa] fractures are irregular. By σ 3=20 to 30 [MPa], triaxial tests confirm the fracture network at an angle of approximately 60 degrees. By σ 3 over 30 [MPa] in gray sandstone comes to the appearance of fractures. Fracture of the material performed by the process of sliding along tangential stress planes without cracking.