Study on blast‐induced cracks penetration characteristics of double water jet slotted boreholes

Abstract

Abstract Studying the penetration characteristics of blast‐induced cracks during double water jet slotted boreholes blasting is theoretically and practically significant since it acts both by the “superposition effect” of explosion‐induced stress waves and the “guiding effect” of water jet slots. A combination of experimental testing and numerical simulation was adopted to investigate the transmission law of explosion‐induced stress waves and the propagation law of blast‐induced cracks first. Then the penetration characteristics of blast‐induced cracks was analyzed according to rock blasting theory and rock fracture mechanics theory. The results indicate that the rock between the two boreholes is mainly subjected to a tensile failure mode due to the combined effect of the “superposition effect” of explosion‐induced stress wave and the “guiding effect” of water jet slot during double water jet slotted boreholes blasting. The hole spacing significantly affects the penetration mode of blast‐induced cracks during double water jet slotted boreholes blasting, and unless it reaches a certain value, a single flat through‐crack will form between two slotted boreholes. In addition, when the blast‐induced cracks successfully penetrate each other, the hole spacing of double water jet slotted boreholes increases by 33.3% compared with that of double circular boreholes under the same conditions. The research results can provide guidance for the application of directional controlled blasting technology with water jet assistance.

Keywords

• blast‐induced crack
• crack penetration characteristics
• double water jet slotted boreholes blasting
• hole spacing
• water jet slot