(1. College of Hydraulic and Environmental Engineering，China Three Gorges University，Yichang，Hubei 443002，China；
2. Chongqing Engineering Technology Research Center of Industrial Explosive Materials，China Gezhouba Group Explosive Co.，Ltd.，Chongqing 401121，China；3. State Key Laboratory of Water Resources and Hydropower
Engineering Science，Wuhan University，Wuhan，Hubei 430072，China)
Abstract：In the process of rock fragmentation by blasting，the initiation mode has an important influence on the energy transmission and rock-breaking effect. The accumulated energy effect by collision of two oppositely traveling in-hole detonation waves was proved theoretically，and the energy transmission characteristics under the condition of dual initiation were analysed. The rock-breaking scopes under different initiation modes were calculated adopting a tension and compression-shear statistical damage model，and the fragmentation size distributions under different initiation modes were also investigated by comparing the field test results of bench blasting. The results show that when the two in-hole detonation waves collide in the middle of the borehole，the pressure near the collision point is greater than the sum of the strength of the two detonation waves and the local rock fragmentation degree is significantly improved. Under the condition of dual initiation，the volumes of tension and compression-shear failure zones of rock mass near the borehole are larger than those of bottom，top or middle initiation. When the initiation point position of in-hole dual initiation is changed，the volume of the compression-shear failure zone changes little but the volume of the tension failure zone changes obviously. Therefore，through reasonably designing the location and quantity of the initiation points，the spatial distribution of explosion energy can be adjusted by the collision of detonation wave and shock wave to improve the fragmentation degree of local rock and to meet different engineering requirements.
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2019, Vol. 38 
