The caustic method is applied to compressive shear experiment and used to detect the stress intensity factors of cracks prefabricated on plexiglass sample. Loading, friction of crack planes and influence among cracks ...The caustic method is applied to compressive shear experiment and used to detect the stress intensity factors of cracks prefabricated on plexiglass sample. Loading, friction of crack planes and influence among cracks are not needed to know as they are combined and transformed into the caustic shadow used in detecting the stress intensity factor. Even boundary condition is not necessary. Therefore it is effective to determine the stress intensity factor of compressive shear crack.展开更多
In this paper, the crack initiation characteristics of compression-shear plane crack with hydraulic pressure were studied by using theoretical analysis and experimental verification methods. The formula derivation pro...In this paper, the crack initiation characteristics of compression-shear plane crack with hydraulic pressure were studied by using theoretical analysis and experimental verification methods. The formula derivation process of stress intensity factor of crack tip and open-type crack initiation angle and initiation strength was expounded in detail. Cement mortar specimens prefabricated with open-type crack were made for biaxial compression test. The results show that the mode I stress intensity factor is inversely proportional to the dip angle of pre-exciting crack, water pressure and crack width. The fracture toughness is most easily achieved when the dip angle of pre-exciting crack is 60°. The mode II stress intensity factor is symmetrically distributed with the dip angle and independent of the water pressure and crack width. For open-type crack, the crack initiation angle decreases with the increase of the dip angle of pre-exciting crack, water pressure and crack width;the crack initiation strength is inversely proportional to the water pressure and proportional to the lateral pressure. The research results can provide ideas for the study of crack initiation under the coupling of ground stress and osmotic pressure in tunnel engineering.展开更多
基金The Specialized Funds for National Key Basic Study (G1998040704), the Dual Project of China Earthquake Admini-stration (9691309020301), and National Natural Sciences Foundation of China (46764010).
文摘The caustic method is applied to compressive shear experiment and used to detect the stress intensity factors of cracks prefabricated on plexiglass sample. Loading, friction of crack planes and influence among cracks are not needed to know as they are combined and transformed into the caustic shadow used in detecting the stress intensity factor. Even boundary condition is not necessary. Therefore it is effective to determine the stress intensity factor of compressive shear crack.
文摘In this paper, the crack initiation characteristics of compression-shear plane crack with hydraulic pressure were studied by using theoretical analysis and experimental verification methods. The formula derivation process of stress intensity factor of crack tip and open-type crack initiation angle and initiation strength was expounded in detail. Cement mortar specimens prefabricated with open-type crack were made for biaxial compression test. The results show that the mode I stress intensity factor is inversely proportional to the dip angle of pre-exciting crack, water pressure and crack width. The fracture toughness is most easily achieved when the dip angle of pre-exciting crack is 60°. The mode II stress intensity factor is symmetrically distributed with the dip angle and independent of the water pressure and crack width. For open-type crack, the crack initiation angle decreases with the increase of the dip angle of pre-exciting crack, water pressure and crack width;the crack initiation strength is inversely proportional to the water pressure and proportional to the lateral pressure. The research results can provide ideas for the study of crack initiation under the coupling of ground stress and osmotic pressure in tunnel engineering.
