作者机构：
[Rao, QH] Cent S Univ, Coll Resources Environm & Civil Engn, Changsha 410083, Peoples R China.;Changsha Commun Univ, River & Sea Dept, Changsha 410076, Peoples R China.;Cent S Univ, Open Lab Mech, Changsha 410083, Peoples R China.
通讯机构：
[Rao, QH] C;Cent S Univ, Coll Resources Environm & Civil Engn, Changsha 410083, Peoples R China.
关键词：
Mode II fracture toughness;rock;fracture;stress analysis;specimen thickness
摘要：
Anti-symmetric four-point bending specimens with different thickness, without and with guiding grooves, were used to conduct Mode II fracture test and study the effect of specimen thickness on Mode II fracture toughness of rock. Numerical calculations show that the occurrence of Mode II fracture in the specimens without guiding grooves (when the inner and outer loading points are moved close to the notch plane) and with guiding grooves is attributed to a favorable stress condition created for Mode II fracture, i.e. tensile stress at the notch tip is depressed to be lower than the tensile strength or to be compressive stress, and the ratio of shear stress to tensile stress at notch tip is very high. The measured value of Mode II fracture toughness K<inf>II C</inf> decreases with the increase of the specimen thickness or the net thickness of specimen. This is because a thick specimen promotes a plane strain state and thus results in a relatively small fracture toughness.
作者机构：
Cent S Univ, Coll Resources Environm & Civil Engn, Changsha 410083, Peoples R China.;Changsha Commun Univ, Dept River & Sea, Changsha 410076, Peoples R China.;Cent S Univ, Open Lab Mech, Changsha 410083, Peoples R China.;[Rao, QH; Sun, ZQ] 中南大学资源环境与建筑工程学院;[Wang, GY] 长沙交通大学河海工程系
关键词：
Mode II fracture;fracture mechanism;rock;direct shearing test;guiding groove
摘要：
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