A three-dimensional test system for simulating the permeability characteristics of unloaded coal and rock mass

Abstract

The invention provides a three-dimensional simulation pressure relief coal and rock mass permeability characteristic test system which comprises a coal and rock mass sealing tank, axial pressure and confining pressure loading devices, constant-pressure gas loading and flow monitoring system, a stress monitoring system and a strain monitoring system. The coal and rock mass sealing tank comprises a protective layer and a protected layer, the protective layer is divided into a center stoping region and a boundary protective region, a simulation stoping layer is arranged in the center stoping region and comprises a plurality of pressure-bearing flexible air bags, the pressure-bearing flexible air bags are sequentially arranged along stoping directions and are enclosed by a rectangular frame, every two adjacent pressure-bearing flexible air bags are relatively positioned at intervals by a partition plate, and a guide pipe is connected with each pressure-bearing flexible air bag and extends out of the coal and rock mass sealing tank. The three-dimensional simulation pressure relief coal and rock mass permeability characteristic test system has the advantages that true stress conditions of the periphery of the protective layer in stoping procedures can be truly simulated by the three-dimensional simulation pressure relief coal and rock mass permeability characteristic test system, accordingly, strain-stress and permeability measurement results are close to reality, and equipment bases can be provided for designing exploitation pressure relief effect analysis and pressure relief gas extraction schemes for protective layers.

Description

[0001] Technical field: [0002] The invention belongs to the technical field of mine engineering, and in particular relates to a test system for three-dimensionally simulating the permeability characteristics of unloaded coal and rock mass. [0003] Background technique: [0004] In the process of coal seam mining for the prevention and control of gas disasters in multi-coal seam mines and the application of protective layer mining technology to prevent and control coal and gas outburst disasters, the mining of coal seams will cause the pressure relief of adjacent coal and rock masses, the stress state will change, and a large number of cracks will be generated. The permeability characteristics of coal and rock mass in the fracture zone will change significantly, which will affect the flow and accumulation characteristics of gas. In order to improve the extraction efficiency of pressure relief gas and avoid the occurrence of pressure relief gas disasters, it is necessary to stu...

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Problems solved by technology

Existing test devices usually include a test box, a pressure loading system, a gas loading and flow monitoring system, and a stress-strain measurement system. The width of the test box is small, generally no more than 30 cm, and it can only conduct research on seepage characteristics under two-dimensional deformation conditions. The test box is equipped with a protective layer and a protected layer. However, during the mining process of the protective layer, there is no protective boundary set, and only the plane stress and strain monitoring under two-dimensional conditions can be carried out, so the protective layer cannot be simulated. During the mining process, the real stress conditions around it, the measurement results of permeability and strain stress are not accurate enough, which will have a certain impact on the design of the gas drainage plan

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