A device and method for prefabricating cracks at any angle inside a coal sample

Abstract

The invention discloses a device and a method for prefabricating cracks in a coal rock sample at any angle. The device comprises a position control module, an angle adjusting module, a mechanical-hydraulic combined cutting module and a laser ranging module. The position control module is in threaded connection with the upper end of the angle adjusting module; the mechanical-hydraulic combined cutting module is fixedly connected with the angle adjusting module through a threaded connecting shaft seat; a stabilizer is mounted on the outer side of the position control module; the stabilizer is foldable, so the device can be stabilized in drilling holes with different diameters; the angle adjusting module realizes 90-degree prefabricated crack angle adjustment through a steering bottom support; high-pressure water spraying cutter teeth and a laser distance measuring sensor are arranged in the mechanical-hydraulic combined cutting module; the mechanical-hydraulic combined cutting module canrotate synchronously, the length of a crack is monitored in real time, the high-pressure water spraying cutter teeth are pushed by hydraulic power to extend, and jet flow nozzles are arranged at thetop ends of the cutter teeth and can achieve the combined effect of mechanical cutting and hydraulic cutting. Steps are simple, and the operation is convenient.

Description

technical field [0001] The invention relates to the field of experimental research on coal-rock mechanics, in particular to a device and method for prefabricating cracks at any angle inside a coal-rock sample. Background technique [0002] In recent years, with the rapid development of deep underground engineering, higher requirements have been put forward for the research of rock mechanics, rock mass mechanics, and rock mass dynamics. In field practice, there are many intricate joints and fissures inside the coal and rock masses; in addition, most of the coal and rock mass dynamic disasters in deep underground engineering, such as rock burst, coal and gas outburst, and water inrush, occur in the fault structure zone nearby. The experimental research on coal and rock mechanics has gradually developed from the initial indifference or less concern about the consistency between the internal structure of coal and rock samples and the actual site, and the emphasis on the consist...

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Problems solved by technology

Chinese patent CN209014352U discloses a prefabricated cracked rock-like preparation mold, Chinese patent CN206057056U discloses a tool for making prefabricated cracks in concrete test blocks, Chinese patent CN206812175U discloses a mold device for prefabricated rectangular cracked test blocks, The above-mentioned one type of prefabricated crack method is to fix the steel plate on the mold and then pour concrete, take out the steel plate to form artificial cracks, and the position and angle of the cracks cannot be controlled arbitrarily

Chinese patent CN208133233U discloses a prefabricated crack test block mold with adjustable angle. The mold forms different angles through the cooperation of limit blocks and different slots. The important thing is that the mold can only prefabricate cracks in the process of rock simulation samples such as cast-in-place concrete, and cannot prefabricate cracks on original rock samples.

The above-mentioned various prefabricated crack methods are largely limited by the test block mold and cannot be adjusted at any angle. Creating cracks on the side is not absolutely prefabricating cracks inside the coal rock sample, but only creating cracks at a specific angle and a specific size or range for a specific shape of the test block

[0004] The existing prefabricated crack technology basically emphasizes the processing of cracks on the side surface of the test block when manufacturing the mold, which can neither ensure that the crack is formed as an ideal crack, nor can it effectively simulate the internal crack shape in combination with the actual situation on site; it weakens the existing test block from the inside The Problem of Machining Ideal Cracks

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