doi:10.16186/j.cnki.1673-9787.2020060044

Received:2020/06/13

Revised:2020/12/02

Published:2022/03/15

Study on microscopic damage characteristics of coal under liquid nitrogen soaking

REN Yongjie1,2, WEI Jianping1,2,3, LI Bo1,2, ZHANG Lulu1,2, WANG Zeqi1,2

1.State Key Laboratory Cultivation Base for Gas Geology and Gas Control, Henan Polytechnic University, Jiaozuo  454000, Henan, China；2.School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo  454000, Henan, China；3.The Collaborative Innovation Center of Coal Safety Production of Henan, Jiaozuo  454000, Henan, China

Abstract: In order to study the variation laws of internal crack structures of coal rock under liquid nitrogen soaking,the CT scanning experiments were carried out to compare and analyze the effects of liquid nitrogen soaking on the microstructure of coal rock cracks.The results showed that: The internal structure of coal rock was damaged by the cold action of liquid nitrogen soaking,and the degree and form of damage were affected by water content.After soaking in liquid nitrogen,the volume of maximum primary crack increased by 340.8% and 326.3% of dry and saturated coal rock samples,respectively.The contraction-frost-expansion stress was exhibited in saturated coal rock samples,and a new crack of 6.78 mm² was generated.The fractal dimension of the saturated coal rock samples was increased by 0.54%,which could be calculated by MATLAB.These new cracks covered a wide range,and the transverse and longitudinal cracks interconnected with each other,which resulted in the increase of gas flow path.The study in this paper could provide guidance for studying the permeability increasing mechanism of the coal rock by liquid nitrogen cold socking.

Key words:coal rock;liquid nitrogen soaking;CT;internal structure;fractal

液氮冷浸作用下煤岩细观损伤特性研究_任永婕.pdf