Performance of water-coupled charge blasting under different in-situ stresses

Water-coupled charge blasting is a promising technique to efficiently break rock masses. In this study, numerical models of double boreholes with water-coupled charge are established using LS-DYNA and are calibrated by the tests of rock masses subjected to explosion loads to examine its performance. The crack levels of rock mass induced by water-coupled charge blasting and air-coupled charge blasting are first compared. It is found that water-coupled charge blasting is more appropriate to fracture deep rock mass than air-coupled charge blasting. In addition, the effects of rock properties, water-coupled charge coefficients, and borehole connection angles on the performance of water-coupled charge blasting are investigated. The results show that rock properties and water-coupled charge coefficients can greatly influence the crack and fragmentation levels of rock mass induced by water-coupled charge blasting under uniform and non-uniform in-situ stresses. However, changing borehole-connection angles can only affect crack and fragmentation levels of rock mass under non-uniform in-situ stresses but barely affect those under uniform in-situ stresses. A formula is finally proposed by considering the above-mentioned factors to provide the design suggestion of water-coupled charge blasting to fracture rock mass with different in-situ stresses.