Effect of ultrasonic excitation time on pore and crack structure and permeability characteristics of coal

doi:10.16265/j.cnki.issn1003-3033.2024.09.1234

Abstract

Abstract:

In order to explore the damage characteristics of coal under different ultrasonic excitation time, the ultrasonic excitation test system, nuclear magnetic resonance imaging system, stereo microscope and automatic permeability test system of coal core were used to analyze the changes of pore structure, surface crack and permeability characteristics of coal under different ultrasonic excitation time. The results show that with the increase of ultrasonic excitation time, the change rates of T2 spectral peak area, total porosity, surface fracture area and permeability of small, medium and large pores in coal are linearly increased. When the coal body is excited by ultrasonic for 30 to 150 min, the change rate of T2 peak area of micro, medium and large pores increase from 14.60%, 52.50% and 24.90% to 61.30%, 145.50% and 235.70%, respectively. The total porosity change rate, surface crack area change rate and permeability change rate increased from 5.04 %, 47.27 % and 41.67 % to 24.93 %, 127.91 % and 208.33 %, respectively. Under the excitation of different ultrasonic time, the change rate of permeability of the coal and the change rate of total porosity and the change rate of surface cracking area are in line with the linear increasing relationship, with the increase of ultrasonic excitation time, the pore and crack modification effect of coal is enhanced, and the permeability can be improved.

Key words: ultrasonic excitation duration, fracture structure, permeability characteristics, nuclear magnetic resonance, porosity

CLC Number:

X935

HAO Hejie, WANG Ruizhe, YANG Erhao, QIU Yue, ZHANG Xiaoying, LIN Haifei. Effect of ultrasonic excitation time on pore and crack structure and permeability characteristics of coal[J]. China Safety Science Journal, 2024, 34(9): 155-164.

Figures/Tables 11

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序号	质量/g	直径/mm	高度/mm	波速/(km·s^-1)
1	283.1	50.0	100.0	1.869
2	280.3	50.0	100.3	1.784
3	282.1	50.2	100.2	1.897
4	281.2	49.9	100.1	1.772
5	282.4	50.0	100.8	1.945