Quantitative evaluation test method for coal core damage

A technology of quantitative evaluation and testing method, applied in the quantitative evaluation and testing of coal core damage, testing the field of coal core damage, can solve the problems that X-ray and CT measurement cannot be carried out in real time, complicated operation and high cost, and achieve accurate and intuitive calculation methods. Simple equipment and simple test steps

Active Publication Date: 2019-12-31
CHINA UNIV OF MINING & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the commonly used techniques for studying the internal damage and fracture behavior of rock materials include resistivity, acoustic emission, electromagnetic radiation, wave velocity, microseismic, X-ray, and CT, etc. X-ray and CT measurements cannot be performed in real time

Method used

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  • Quantitative evaluation test method for coal core damage
  • Quantitative evaluation test method for coal core damage
  • Quantitative evaluation test method for coal core damage

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0091] A quantitative evaluation test method for coal core damage, the test steps in creep damage are as follows:

[0092]① Process the coal rock sample into a cylindrical coal core with a diameter of 50 mm and a length of 100 mm; put the coal core in an oven at 45°C for 24 hours for drying; select four flat areas on the outer surface of the core of the coal core to avoid the existence of micro-cracks Grind the position to be pasted with sandpaper, clean up the floating dust, apply the adhesive, cover the strain gauge 14, press the strain gauge 14, and paste the remaining strain gauges 14 in sequence after the adhesive solidifies; welding;

[0093] ② Put the coal core into the rubber sleeve 13 and place it in the pressure chamber 12; pass the strain gauge lead wire 15 through the plug II 18 to ensure that the strain gauge lead wire 15 is not bent; connect the strain gauge lead wire 15 to the strain collector 21 , connecting the strain collector 21 and the displacement sensor ...

Embodiment 2

[0124] A quantitative evaluation test method for coal core damage, the test steps in the cycle pulse air pressure anti-reflection are as follows:

[0125] ① Process the coal rock sample into a cylindrical coal core with a diameter of 50 mm and a length of 100 mm; put the coal core in an oven at 45°C for 24 hours for drying; select four flat areas on the outer surface of the core of the coal core to avoid the existence of micro-cracks Grind the position to be pasted with sandpaper, clean up the floating dust, apply the adhesive, cover the strain gauge 14, press the strain gauge 14, and paste the remaining strain gauges 14 in sequence after the adhesive solidifies; welding;

[0126] ② Put the coal core into the rubber sleeve 13 and place it in the pressure chamber 12; pass the strain gauge lead wire 15 through the plug II 18 to ensure that the strain gauge lead wire 15 is not bent; connect the strain gauge lead wire 15 to the strain collector 21 , connecting the strain collecto...

Embodiment 3

[0161] A quantitative evaluation test method for coal core damage, the test steps of which are damaged by triaxial stress loading are as follows:

[0162] ① Process the coal rock sample into a cylindrical coal core with a diameter of 50 mm and a length of 100 mm; put the coal core in an oven at 45°C for 24 hours for drying; select four flat areas on the outer surface of the core of the coal core to avoid the existence of micro-cracks Grind the position to be pasted with sandpaper, clean up the floating dust, apply the adhesive, cover the strain gauge 14, press the strain gauge 14, and paste the remaining strain gauges 14 in sequence after the adhesive solidifies; welding;

[0163] ② Put the coal core into the rubber sleeve 13 and place it in the pressure chamber 12; pass the strain gauge lead wire 15 through the plug II 18 to ensure that the strain gauge lead wire 15 is not bent; connect the strain gauge lead wire 15 to the strain collector 21 , connecting the strain collecto...

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Abstract

The invention discloses a quantitative evaluation test method for coal core damage. According to the method of the invention, a triaxial loading system is used for applying confining pressure and porepressure to the coal rock core; the axial strain of the matrix of the coal core is recorded in real time through a strain gauge; the overall axial displacement of the coal core is recorded through adisplacement sensor; volume strain generated by the microcrack evolution of the coal core can be obtained through calculation; and due to the fact that the volume strain is closely related to a damagedegree, the damage variable of the coal core can be quantitatively calculated according to a continuous medium damage mechanics theory; a permeability change rule in a damage process is measured in real time according to a pulse attenuation method; the permeability change rule is compared with the calculated damage variable, so that a corresponding relation between damage and permeability can bedirectly established. According to the test method of the invention, required equipment structures and test steps are simple; and the calculation method is accurate and visual. The test method has definite physical significance, and can be used for the quantitative evaluation of damage variables and permeability evolution in experimental processes such as cyclic pulse air pressure permeability increase, creep deformation damage, and triaxial compression.

Description

technical field [0001] The invention relates to a method for testing coal core damage, in particular to a quantitative evaluation test method for coal core damage, which belongs to the technical field of coal rock mechanics and engineering testing. Background technique [0002] It is generally believed that coal rock is a complex porous medium composed of matrix and fractures. The microporous structure in the coal matrix provides a large adsorption space for gas and other adsorbing gases, while most of the gas in the fractures exists in a free state. Adsorptive gas will expand and deform when adsorbed on the coal matrix, increasing the volume strain of the matrix, which is basically in the elastic range. Crack structures such as micro-cracks and micro-defects gradually expand and aggregate under external pressure and environmental influences, leading to the deterioration of their mechanical properties. This process is often regarded as the accumulation process of damage. At...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/36
CPCG01N3/36G01N2203/001G01N2203/0019G01N2203/0046G01N2203/0073G01N2203/0682
Inventor 魏明尧刘应科康建宏刘春
Owner CHINA UNIV OF MINING & TECH
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