High-power microwave hole interior fracturing device for engineering rock mass

Abstract

The invention provides a high-power microwave hole interior fracturing device for an engineering rock mass. The high-power microwave hole interior fracturing device comprises a high-power microwave generator, a high-power microwave coaxial heater, a high-power low-loss microwave coaxial transmission line and a microwave power self-adaption adjusting and controlling system; the high-power microwavegenerator comprises a continuous wave magnetron, a permanent magnet, a wave guide excitation cavity, a coaxial annular device, a coaxial matched load, a coaxial coupling converter, a wave guide coaxial converter and an output wave guide; the high-power microwave coaxial heater comprises a transmission line interior conductor, a transmission line exterior conductor, a microwave input joint, a microwave short circuit seal cover and a conductor supporting cylinder; the high-power low-loss microwave coaxial transmission line comprises an input end coaxial line, middle segment coaxial lines and anoutput end coaxial line, wherein the input end coaxial line is connected with the output end coaxial line through a plurality of middle segment coaxial lines which are connected in series; the microwave power self-adaption adjusting and controlling system comprises an impedance matching adjuster, a microwave power controller and a temperature sensor, and the real-time matching of impedance is carried out on the microwave power through the impedance matching adjuster.

Description

technical field [0001] The invention belongs to the technical field of geotechnical engineering and mining engineering, and in particular relates to a high-power microwave in-hole fracturing device for engineering rock mass. Background technique [0002] Microwave-assisted rock-breaking technology is a new rock-breaking technology with great potential. Before cutting rocks with mechanical tools, microwaves are used to pre-irradiate rocks to reduce mechanical properties such as uniaxial compression, tensile strength, and point load strength. The problem that the cutter is easy to wear when the mechanical method breaks the hard rock can improve the rock breaking efficiency and reduce the rock breaking cost. The microwave-assisted fracturing technology can effectively release the stress of the deep rock mass, and increase the pre-cracking of the rock mass on the basis of the stress release hole, so as to form a fracture zone inside the surrounding rock, reduce the internal rock...

AI Technical Summary

Problems solved by technology

[0004] However, at present, most traditional microwave generators are box-type structures using single-mode or multi-mode resonant cavities. Microwaves are reflected in a closed cavity, so that the rocks in the cavity can complete the absorption of microwaves. The frequency of microwaves is 915MHz. Or 2450MHz, the maximum power of microwave output is about 30kW, this type of microwave generator is only suitable for indoor experiments, and can be used to study the influence of microwave radiation on rock thermophysical and mechanical properties, but it cannot meet the actual engineering application

Although the microwave power of 30kW can meet the fracturing needs of small-sized rock blocks, the microwave power is still too small for the engineering rock mass in actual engineering. The heating rate of the rock body is low, which will lead to local melting of the engineered rock mass, and cannot produce the desired fracturing effect

Then can multiple sets of low-power superposition methods be used? The answer is also no, because when multiple microwave heaters are superimposed and heated, the microwave energy radiated by each microwave heater will be mutually absorbed before being absorbed by the engineering rock mass. Coupled or offset, rock fracturing cannot be realized in the end

In addition, although there are still some microwave generators that can meet high-power output, these microwave generators are all industrial-grade, and the microwave generators are bulky, and they all provide magnetic fields through electromagnets, and use Y-junction circulators to reflect power. isolation, this type of microwave generator cannot be moved to the engineering site for application, nor does it have the conditions to combine with rock-breaking machinery

[0005] At present, traditional microwave heaters cannot meet the requirements of high-power in-hole fracturing. Due to the low power capacity of traditional microwave heaters and the small range of microwave radiation, if high-power microwaves are forcibly input, air ionization and shocks will occur. Wear and spark phenomenon, thus damaging the high-power microwave cracking device

[0006] At present, the microwave coaxial transmission line with traditional structure cannot meet the requirements of high-power in-hole fracturing, its power capacity is low and the microwave energy loss is large during long-distance transmission, and the outer diameter of the microwave coaxial transmission line cannot effectively meet the rock mass hole size requirements , and it is not convenient to install and disassemble on site

[0007] In addition, because the current technical scheme of microwave cracking engineering rock mass still mainly stays in the indoor test stage, the microwave power output by the microwave generator acts on the rock sample in a constant state, but because the temperature of the rock sample varies greatly , will cause the microwave properties (dielectric constant, dielectric loss, etc.) When dynamic changes occur, if a constant microwave power acts on the rock sample, it will inevitably lead to impedance mismatch, and the direct consequence is the increase of microwave reflection power, which will not only reduce the stability of microwave equipment, but also reduce the utilization efficiency of microwave energy. reduce

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