Effect of loading point position on
fracture mode of rock
fracture mode of rock
(1. College of Resources, Environment and Civil Engineering,
Central South University, Changsha 410083, P.R.China;
2. River and Sea Department, Changsha Communications University,
Changsha 410076, P.R.China;
3. Open Laboratory of Mechanics, Central South University,
Changsha 410083, P.R.China)
Central South University, Changsha 410083, P.R.China;
2. River and Sea Department, Changsha Communications University,
Changsha 410076, P.R.China;
3. Open Laboratory of Mechanics, Central South University,
Changsha 410083, P.R.China)
Abstract: Anti-symmetric fourpoint bending specimen with different loading point positions was used to study effect of loading point position on fracture mode of rock in order to explore a feasible method for achieving Mode Ⅱ fracture and determining Mode Ⅱ fracture toughness of rock, KⅡC. Numerical and experimental results show that the distance between the inner and outer loading points, L1+ L2, has a great influence on stresses at notch tip and fracture mode. When L1+L2＞0.5L or 0.1L＜L1+ L2＜0.5L, maximum principal stress σ1 exceeds the tensile strength σt. The ratio of τmax/σ1 is relatively low or high and thus Mode Ⅰ or mixed mode fracture occurs. When L1+L2＜0.1L,σ1 is smaller than σt and the ratio of τmax/σ1 is much higher, which facilitates the occurrence of Mode Ⅱ fracture.
Key words: fracture mode; loading point position; stress analysis; rock