Failure pattern and evolution mechanism of locking section in rock slope with three-section landslide mode

The geological structure and mechanical properties of locking section are the key control factors to the rock slope with three-section landslide mode. According to the characteristics of the geological structure of three-section landslide, physical model tests and particle flow numerical simulation method were used to study the influences of the angle of rock bridge of locking section (the angle between the line of the end of the tensile crack to the end of the creep section and the horizontal direction) on the failure mode and failure evolution of locking section in the rock slope with three-section landslide mode. The failure modes of the locking section can be summarized as tensile coalescence and mixed tensile-shear coalescence. With the increase of the angle of rock bridge of the locking section, the failure mode is changed from the tensile coalescence to the mixed tensile-shear one. When the angle is less than 90°, the failure of slope is caused by the tensile coalescence. When the angle is between 90°and 110°, the failure of slope is caused by the mixed tensile-shear coalescence. When the angle is greater than 110°, the failure occurs in other areas instead of the locking section. Based on the analysis of the strain-time curve of locking section, the tensile zone of the locking section decreases gradually with the increase of the angle of the rock bridge of the locking section, and its stress state is changed from the whole tension to the whole compression.