A New Safety Control Method of Blasting Excavation in High Rock Slope with Joints

Abstract

In this paper, a new safety control method of the jointed slope under blasting excavation is presented. The spatial distribution of blasting damage and time-history characteristic of dynamic stability around the joint were investigated carefully based on the secondary development of the explicit FE code, LS-DYNA. Results clearly indicated that the evolution law of damage and stability are opposite with the change of joint angle, and the dual-controlled mechanism of damage extension and stability fluctuation exists in the safety control of the high rock slope with joints. Then a new safety control method is proposed by implementing the equivalent Blasting Safety Control Standard (BSCS) which includes coupled effects of damage and stability. Results reveal that a critical joint angle exists, and if the inclination is larger than the threshold value, the BSCS depends on damage extension, otherwise it was determined by stability fluctuation. Finally, site experiments are implemented carefully based on the blasting excavation of the famous Baihetan high rock slope with columnar joint in China to verify the rationality of the new control approach. Sonic wave test, displacement measurement and blasting vibration test are implemented for nearly two years to track the evolution process of damage and stability of the jointed slope. Experimental results demonstrate that the new approach could improve the accuracy rate of control by 40%.