Numerical Design Optimization of Electric Discharge Impulse Crushing Method

摘要

The purpose of this research is to analyze the fracture process and achieve design optimization of asplitting method for concrete and rocks termed the electric discharge impulse crushing method (EDICM).The EDICM utilizes the cartridges being set in boreholes in the splitting target. The cartridge has a thinmetal wire and is filled with nitromethane. By applying the electric discharge to the wire in the cartridge,plasma is caused leading to the vaporization of the wire. Then the deflagration of the nitromethanecommences, which generates borehole pressure for splitting the target. Although the required splittingtime is roughly several hundred micro-seconds and much slower than ordinary blasting, the fracturingstill completes in quite short time and understanding the fracture process of opaque and brittle materialssuch as rock and concrete in this time scale is of academic importance.This paper proposes the application of dynamic fracture process analysis (DFPA) based on dynamicFEM with the result of borehole pressure measurement in the EDICM. First the borehole pressuremeasurement was conducted for austenite stainless steel (ASS) and the characteristics of boreholepressure in the EDICM were modeled considering the deflagration process of the nitromethane. Thenwith the modeled borehole pressure, the DFPA was conducted to simulate and predict the fractureprocess in concrete by the EDICM for a particular alignment of boreholes. To verify the results of theDFPA, then fracturing tests were also conducted for concrete blocks with the same alignment ofboreholes as analyzed in the DFPA. The predicted fracture patterns by DFPA were found to agree wellwith those by the fracturing tests. Therefore the proposed method can be used for the estimation ofoptimum splitting design for concrete in the EDICM.