Research progress and prospects of ultrasonic vibration in coal rock fracturing

In order to promote the technological development of ultrasonic vibration induced cracking of coal and rock masses, improving the efficiency of coalbed methane production and hard rock excavation in mines, it reviews the development history of ultrasonic technology, summarizing the application status and research progress of ultrasonic vibration in fracturing coal and rock mass, and the key obstructive technology problems and development trends of ultrasonic vibration in the field of coal and rock fracturing are clarified. ① The technical problems of traditional technologies in the fields of coal seam methane production and hard rock excavation in mines is summarized, introducing unique advantages and application fields of ultrasonic technology, besides the development stages and corresponding performances of ultrasonic generator and ultrasonic transducer are described; ② The equipment and process of ultrasonic vibration to promote coalbed methane desorption and permeability increase are induced, analyzing the current situation of promoting permeability increase of coalbed methane by ultrasonic vibration, and the mechanism of pressure reduction, acceleration, potential energy and kinetic energy increase of coalbed methane under ultrasonic cavitation effect, mechanical vibration effect and thermal effect to promote its desorption and permeability increase is expounded; ③ The equipment and process of ultrasonic vibration rock fragmentation are generalized, describing the progress of ultrasonic vibration crushing of hard rock, and it reveals the internal mechanism of hard rock breaking caused by mechanical vibration effect and thermal effect of ultrasonic vibration, such as fatigue damage, subcritical propagation of microcracks, uneven thermal expansion or mineral phase transformation of mineral particles, and deterioration of rock physical and mechanical properties; ④ In view of limitations of ultrasonic generator, transducer and ultrasonic vibration in coal and rock mass fracturing in mines, four suggestions are put forward for the research focus on the efficient application of ultrasonic vibration induced fracturing of coal and rock masses in the field in the future: research and development of high-performance explosion-proof ultrasonic generator and transducer, in-depth analysis of the mechanism of increasing permeability by ultrasonic vibration and design of pipeline technology framework, development and test of multi-function and multi-field coupling indoor ultrasonic vibration cracking coal and rock mass equipment, research and application of anti-interference ultrasonic vibration equipment in underground mines.