ABSTRACT:

Fracture process analysis was performed to simulate a newly developed rock splitting method termed the Electric Discharge Impulse Method (EDICM). From the pressure measurements conducted for austenite stainless steel, characteristics of pressure waveform for EDICM were modeled by considering the deflagration process of the self-reactive liquid used in EDICM. Then fracture process analysis in EDICM for a polymethylmethacrylate (PMMA) specimen was successfully simulated. Therefore, by using the proposed modeling method for the deflagration process in EDICM, estimation of the optimum splitting design for rock and concrete is possible.

1 INTRODUCTION

Blasting is one of the most economical splitting techniques in terms of the required time and cost. However, its application is occasionally limited by strict legal regulation of the use of explosives and generates adverse vibration effects on surrounding environment. When this limitation is imposed on in situ splitting, static rock splitting techniques such as those using a fracturing agent or hydraulic breaker have generally been used. However, these techniques are time-consuming and thus increase the splitting cost. To solve this problem, an alternative splitting technique termed the electric discharge impulse crushing method (EDICM)was developed by Hitachi Zosen Corporation (Sasaki et al. 2009). The advantage of the technique is that the required splitting time is roughly several hundred micro-seconds and its application is not strictly regulated by law in most countries, especially in Japan. Figure 1 shows an example configuration for EDICM. The system consists of a power generator (200 V), an electric discharge impulse generator with a maximum voltage of 6000V, a discharge cable and a discharge cartridge with a scale of several centimeters. A thin metal wire is installed in the cartridge filled with a self-reactive liquid. The cartridge is set in a borehole drilled in the splitting target such as rock or concrete.

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