自然科学版 英文版
自然科学版 英文版
自然科学版 英文版

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中南大学学报(英文版)

Journal of Central South University

Vol. 8    No. 3    September 2001

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Microscopic characteristics of different fracture modes of brittle rock
RAOQiu-hua1, SUN Zong-qi1, WANG Gui-yao2, XU Ji-cheng3, ZHANG Jing-yi3

1.College of Resources, Environment and Civil Engineering, Central SouthUniversity, Changsha 410083, China;
2.River and Sea Department, Changsha Communications University, Changsha 410076, China;
3.Open Lab ofMechanics, Central SouthUniversity, Changsha 410083, China

Abstract:Three types of rock specimens, three-point bending specimen, anti-symmetric four-point bending specimen and direct shearing specimen, were used to achieve ModeⅠ, ModeⅡand mixed modeⅠ-Ⅱfracture, respectively . Microscopic characteristics of the three fracture modes of brittle rockwere studied by SEM technique in order to analyze fracture behaviors and better understand fracture mechanisms of different fracture modes of brittle rock. Test results show that the microscopic characteristics of different fracture modes correspond to different fracture mechanisms. The surface of ModeⅠfracture has agreat number of sparse and steep slip-steps with few tearing ridges and shows strong brittleness. In the surface of ModeⅡfracture there exist many tearing ridges and densely distributed parallel slip-steps and it is attributed to the action of shear stress.The co-action of tensile and shear stresses results in brittle cleavage planes mixed with streamline patterns and tearing ridges in the surface of mixed modeⅠ-Ⅱfracture. The measured ModeⅡfracture toughness KC and mixed modeⅠ-Ⅱfracture toughness Km Care larger than ModeⅠfracture toughnessKC.KC is about 3.5 times KC, and KmC is about 1.2 times KC.

 

Key words: microscopic characteristic; ModeⅡfracture; mixed mode fracture; rock; SEM analysis

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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