Effect of loading point position on fracture mode of rock

À´Ô´ÆÚ¿¯£ºÖйúÓÐÉ«½ðÊôѧ±¨(Ó¢ÎÄ°æ)2001ÄêµÚ5ÆÚ

ÂÛÎÄ×÷ÕߣºÈÄÇﻪ Ëï×Úñý Íõ¹ðÒ¢ Ðì¼Ì³É Õž²ÒË

ÎÄÕÂÒ³Â룺764 - 767

Key words£ºfracture mode; loading point position; stress analysis; rock

Abstract: Anti-symmetric fourª²point 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 ¢ò fracture and determining Mode ¢ò fracture toughness of rock, K_¢òC. 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£¾0.5L or 0.1L£¼L₁+ L₂£¼0.5Lª«, maximum principal stress ¦Ò₁ exceeds the tensile strength ¦Ò_t. The ratio of ¦Ó_max/¦Ò₁ is relatively low or high and thus Mode ¢ñ or mixed mode fracture occurs. When L₁+L₂£¼0.1Lª«,¦Ò₁ is smaller than ¦Ò_t and the ratio of ¦Ó_max/¦Ò₁ is much higher, which facilitates the occurrence of Mode ¢ò fracture.