线弹性阶段卸轴压煤样内瓦斯流动特性试验研究

Experimental study of gas flow characteristics of coal sample under unloading axial stress in linear elastic stage

以二次成型的型煤试件为研究对象,以煤样内瓦斯流动速度为考察参数,对其应力-应变全过程、线弹性阶段卸轴压过程的瓦斯流动特性进行了试验研究,并对比分析了处于弹性阶段的加、卸载过程中瓦斯流动特性。分析结果表明:煤样加载阶段的瓦斯流动特性曲线存在一瓦斯流动困难应力点,且应力值位于线弹性阶段的后期;线弹性阶段卸轴压时,煤样的应力-应变曲线与其内瓦斯流动规律曲线呈反向变化趋势,瓦斯流动速度变化与起始瓦斯流动速度呈正向关系,且煤样强度越大,其瓦斯流动规律变化越复杂,卸轴压过程中仅能够部分还原加载过程煤样内瓦斯流动规律;加载与卸载过程的瓦斯流动规律具有前者分两阶段均匀变化、后者为双曲线型特点;瓦斯流动规律在加载过程对应力影响更敏感,而卸载过程瓦斯流动规律对应力的敏感性只在局部表现。

Taking briquette as studied objects,taking gas flow speed of briquette as studied parameters,the gas flow characteristics of coal sample is studied under the complete stress-strain and unloading axial stress in linear elastic stage;the comparative analysis is done by comparing the gas flow characteristics of loading stage and unloading stage.The results show： the special stress point which makes the gas flow speed minimum appeared in gas flow curve of loading stage,and it belongs to the late of linear elastic stage.In the process of unloading axial stress in linear elastic stage,the reverse trend is shown between stress-stain curve and gas flow characteristical curve;the positive trend is shown between gas flow speed and initial gas flow speed of coal sample;the variation law of gas flow speed is more complex as the addition of strength,only the part of gas flow law is reproduction in the process of unloading axial stress.The laws of gas flow are different in the process of loading stage and unloading stage;the former is uniform change of two stages,the latter is hyperbolic.The influence caused by stress change on gas flow law is more sensitive;it is more obvious in local part of unloading stage.