Abstract: Main concerns in rock engineering are the influences of in-situ stress on the quality of contour surface and its corresponding distribution area after rock blasting and excavation. This paper aims at studying the reason for the occurrence of hanging feet at the corner of right bank abutment groove of Baihetan hydropower station after pre-split blasting excavation. Theoretical analysis is firstly applied to explain the influence of in-situ stress on crack propagation during the stage of explosion stress wave and detonation gas respectively, and then numerical simulation is used for verification. Results show that in-situ stress guides the direction of initial crack propagation during the stress wave stage, while the in-situ stress perpendicular to fracture face inhibits the crack length expansion during the detonation gas stage. Moreover, the higher the in-situ stress, the more significant effect on the initial crack propagation direction and final length. Since the connection direction between blast-holes is inconsistency and in-situ stress is high at the corner of the abutment groove, crack extension deviates the expected direction and is difficult to penetrate at last. Finally, the hanging feet is formed. It can be seen that the in-situ stress seriously affects the quality of the pre-splitting blasting seam, which further causes the phenomenon of blasting and hanging feet at the corner of the abutment groove.

Key words: abutment slot, presplit blasting, in-situ stress, fracture, rock