Optimization of parameters for controllable shock waves pre-splitting in hard rocks in tectonic zones
In order to reduce the impact of hard rock in the structural area of the fully mechanized min-ing face on mining,a controllable shock wave presplitting technique for hard rock was developed through a combination of experiments and numerical simulations.Firstly,a controllable shock wave en-ergy testing platform was built,and the controllable shock wave presplitting tests were conducted using concrete-like materials.Then,by simulating the three-dimensional loading conditions using the continu-um-based discrete element method(CDEM)software,the influence of in-situ stress,shock wave intensi-ty,and elastic modulus on the presplitting range was examined.The results showed that the in-situ stress was inversely proportional to the fracture radius,and the peak stress and the number of shocks were directly proportional to the fracture range.Under the shock energy conditions of a discharge volt-age of 30 kV and a peak pressure of 224 MPa,the presplitting effects of test specimens at different dis-tances from the shock operation point were obtained.Finally,the field application showed that the con-trollable shock wave could significantly affect the development of large whole rock fractures in the hard rock affected area of the mining face.After the shock wave action,the number of rock cracks is more than 3/m2.The rock mass in the presplitting area is loose and angular.The cut rock does not need sec-ondary crushing.The daily advance of the recovery working face is 3～5 m,which is equivalent to the normal mining efficiency.As a new technology for treating the impact zone of hard rock underground actively and proactively in large areas,the controllable shock wave presplitting technology could provide technical support for safe and efficient production in coal mines.
hard rockcontrollable shock waveefficient presplittingdiscrete element CDEM softwarelarge-area processing
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