Abstract：The failure mechanism of the internal rock bridge of the high-steep rock slope is complex. It is important to study the failure of central locking section and the failure mechanisms of slope. The rock bridge was formed by prefabricated cracks at the ends of the rock simple in order to represent the tensile failure in the trailing edge of slope and shear failure in the toe of slope. The conventional triaxial loading test and triaxial loading-unloading test were carried out on three rock bridges of different lengths. The characteristics of stress-strain curves，strength-deformation and the crack propagation types under two types of stress paths were analyzed，and the mechanism of crack propagation was discussed based on the fracture mechanics. The results of test show that the peak strength of specimens and the corresponding strain increased with the increasing of confining pressure and rock bridge length. The peak strain and peak value of rock bridges specimen under the triaxial loading-unloading are greater than those from the conventional triaxial loading test. The “burst failure” and “post-peak rise” characteristic appeared in the stress-strain curve，and the stress-strain curves of some specimens show the “double peak ” phenomena. There are five types of crack propagation in the rock bridge specimens：the coalescence rock bridge，the coalescence specimens upper end-face，the inward circumferential failure，the outward circumferential failure and the coalescence specimens lower end-face. The tension cracks and shear cracks are generated at the tip of the lower joint of rock bridge specimen where the stress concentration occurs. Most of the crack initiation angles are between 40° to 50°. The lab test revealed that the failure mode of locking section in rocky slope was a multi-stage process.
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2017, Vol. 36 
