Influence of microwave irradiation on thermal properties and fracturing mechanism of basalt in rock excavation

Abstract

Microwave fracturing is a promising technique for facilitating the efficient exploitation of deep Earth resources while reducing energy consumption and cutter wear during mechanical excavation. In this study, the thermal properties of basalt under six power levels are investigated and the mechanism of microwave fracturing is elucidated through real-time monitoring and microstructural analysis. The results show that the failure modes of basalt can be categorized into high-temperature melting failure (>300 °C) and low-temperature burst failure (<200 °C). High-power microwave irradiation not only altered the failure mode but also modified the relationship between temperature rise and time. The temperature distribution exhibits a wave pattern, making it more prone to inducing transverse tensile cracks. Dehydration of basalt is triggered when the temperature exceeds 200 °C, which subsequently promotes the initiation of macroscopic cracks. Microscopically, microwave fracturing is mainly driven by thermal stresses, while steam pressure, especially under high-power conditions, plays a dominant role in the fracturing process. These results are anticipated to provide necessary theoretical and technical support for the efficient exploitation of deep Earth resources.

Keywords

microwave fracturing / deep earth resource / failure mode / thermal properties / fracturing mechanism

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