Jordan Journal of Civil Engineering

Vibration Reduction Mechanism and Experiment of Stepped V-Cut Millisecond Blasting


Xinkuan Zou; Jichuan Zhang; Hongchao Shi;


As drilling and blasting are carried out in an urban tunnel, which is adjacent to existing buildings or structures, the balance between blasting-induced vibration reduction and drivage efficiency is a very important problem that must be resolved properly. Therefore, a new cut blast method named Stepped V-cut millisecond blasting (SV-cut) was developed by optimizing the most common used Vertical V-cut blasting method (V-cut). The most significant features of SV-cut lie in the utilization of sub-level interval charging structure and millisecond delay blasting technology in the cuthole and the cut cavity formed from outside to inside sequentially. SV-cut provides advantages of high borehole utilization ratio, low vibration level and satisfying advance per round. Based on the principle of millisecond blasting, the rock fragmentation process and the vibration reduction mechanism of SV-cut are analyzed. Methods of determining blasting parameters, which have significant effects on vibration intensity and cut cavity formed quality, are proposed according to the forming requirements of both outer and inner cut cavity and vibration reduction. In order to compare the cut blast effect and vibration intensity between SV-cut and V-cut, field blasting experiments were performed in the blasting engineering of the Yamalike twin-arc tunnel, which closely passes over existing parallel tunnels. Blasting results show that SV-cut blasting has proven to be an effective tunnel blasting method for both increasing blasting effects and decreasing blasting vibration. Comparing SV-cut with V-cut, SV-cut can increase blasting drivage by about 8.5% and reduce vibration intensity induced by cuthole blasting by at least 30%.


Drilling and blasting, Stepped V-cut, Blasting vibration reduction, Field blasting experiments