Calculation method of charge in deep hole pre-split blasting and optimization of water-coupling charge structure

The development degree of blasting fracture in rock mass is bound up with charging parameters.In view of the poor adaptability of the existing charge calculation methods in the application of deep hole pre-split blasting, a new charge calculation method for deep hole pre-split blasting is proposed, based on the calculation principle of volumetric method, through establishing a simplified calculation model of columnar charge.This paper analyzes the mechanism of hydraulic blasting, optimizes the charge structure of deep hole pre-split water-coupled blasting, and solves the problems of large amount of labor in deep hole plugging, difficulty in plugging of water-bearing formation, and difficulty in dealing with explosion rejection of explosive.The results are applied, the field test of deep hole pre-split blasting in fully-mechanized excavation hard rock is carried out in the hard rock tunnel of Xinyi coal mine.The blasting effect is detected by borehole imager and Sonic tester.The results show that after blasting, number of cracks in the rock of the hole increased; the rock integrity decreased; the rock integrity coefficient of the plugging section decreased to 0.3-0.5; the charging section decreases to 0.1, and the advance speed in the blasting area increases during the driving process of the road-header, which verifies the advantages of the charging calculation method and charging structure.