采矿与安全工程学报2025，Vol.42Issue(2)：472-486,15.DOI:10.13545／j.cnki.jmse.2024.0084
液氮-微波急速冷热冲击下饱水煤损伤及渗流特征研究
Study on the damage and seepage characteristics of water-saturated coal under liquid nitrogen-microwave rapid cold-heat shock
摘要
Abstract
In the hope of disclosing the evolutions of triaxial mechanical properties and seepage charac-teristics of water-saturated coal specimens subjected to liquid nitrogen treatment and rapid cold-hot shock,triaxial loading tests were conducted on coal specimens under different processing conditions by adopting the non-contact digital image processing technique.The following research findings were ob-tained.The surface change is slight for the coal specimen restored to room temperature in the natural state,while it becomes obvious after microwave treatment,with the appearance of secondary fractures.With the increase of microwave power,the specimen experiences a series of changes,including a de-crease in compressive strength and elastic modulus,an increase in Poisson's ratio,an enhancement of transverse deformation capacity,a drop of firmness coefficient and hardness,as well as a growth of damage factor and internal damage,and 800 W microwave exerts the greatest influence.The compaction stage of the specimen is obviously shortened,while the elastic stage,yield stage and destruction stage are prolonged.Among these stages,the destruction stage is the most obvious,and the post-destruction curve gradually flattens,which proves that the destructive stress can still be maintained after destruction,instead of dropping precipitously as a result of instantaneous crushing.That is,the specimen presents a state of low stress and large deformation,and is able to achieve a better permeability enhancement effect under the same pressure environment.The specimen is more noticeably affected by the shear force,and the stress angular point eventually tends to be distributed in a"double fan"shape,which gets increasing-ly pronounced with the rise of microwave power.In the meantime,the specimen damage spreads from the inside to the outside,and its primary fragmentation state progressively evolves from large blocks to small blocks,particles,and powders.After the application of microwave treatment,the permeability changes obviously.To be specific,compared with the naturally restored coal sample,the permeability increases by 52.67％after the application of 200 W microwave treatment,and the rate of increase is 243.81％and 394.25％after the microwave power is raised to 400 W and 600 W,respectively.Particu-larly,800 W microwave treatment brings about the highest rate of increase,886.28％(nearly nine times),marking the most significant permeability enhancement effect.The results of the study can pro-vide a new method of rapid hot and cold shock to enhance the permeability of low-permeability coal seams,which is of great significance to improve the efficiency of underground gas extraction.关键词
非接触式数字图像处理/液氮处理/微波/不同功率/受载煤体/渗透率Key words
non-contact digital image processing/fluid nitrogen treatment/microwaves/different pow-ers/load-bearing coal body/permeability分类
矿山工程引用本文复制引用
齐消寒,刘晓东,马恒,刘忠桦,谢文坤,张颖..液氮-微波急速冷热冲击下饱水煤损伤及渗流特征研究[J].采矿与安全工程学报,2025,42(2):472-486,15.基金项目
国家自然科学基金项目(52074148) （52074148）
