Microwave fracturing of water-bearing sandstones: Heating characteristics and bursting

• Published in: International journal of rock mechanics and mining sciences (Oxford, England : 1997) England : 1997), 2020-12, Vol.136, p.104495, Article 104495
• Main Authors: Zhao, Q.H., Zhao, X.B., Zheng, Y.L., Li, J.C., He, L., Zou, C.J.
• Format: Article
• Language: English
• Subjects: Bursting; Heating characteristics; Heating rate; Irradiation; Mercury; Microwave; Permeability; Pore water; Porosity; Rock properties; Rocks; Sandstone; Saturation; Steam; Vaporization; Water heating
• ISSN: 1365-1609; 1873-4545
• DOI: 10.1016/j.ijrmms.2020.104495

Microwave treatment has been considered as a promising rock breakage method. The weakening mechanism of vaporizing expansion of pore water in sandstone under microwave irradiation was studied in this paper. The effect of water in the heating process was studied by comparing the heating characteristics of dry and saturated sandstones, which was further explained by the mercury intrusion porosimetry tests. Moreover, the influencing factors including rock strength, permeability, saturation degree and microwave power on rock bursting were investigated by comparing the bursting time of water-bearing sandstone samples under microwave irradiation. The results show that water plays a more important role in the heating process of sandstones with higher porosity and lower microwave sensitivity. The heating curves of saturated sandstones can be divided into 3 stages according to the heating rate, which is related to the interaction of water heating and steam escape during microwave irradiation. In addition, it is found that the favorable conditions of water-bearing sandstone bursting under microwave irradiation are low rock strength, low permeability, high saturation degree and high microwave power. This law can be explained by the interaction of rock properties and the generation, increase, diffusion, and escape of steam in rock. •The effect of pore water in the heating process of sandstone is analyzed.•The heating curves of saturated sandstones can be divided into 3 stages.•The weakening mechanism of vaporizing expansion is studied.•The favorable conditions of water-bearing sandstone bursting are derived.