摘要
为了探究预热冻融煤岩在三轴应力下的变形特性,开展液氮冻融前后煤岩三轴卸载试验研究,采用具有图测功能的煤岩三轴伺服试验系统,对煤岩进行预热干燥和预热干燥后液氮冻融预处理,对煤岩损伤演化及力学特点进行研究。研究结果表明:煤岩扩容过程的4个阶段分别为压缩阶段、扩容开始阶段、扩容加速阶段、扩容破坏阶段;在不同初始围压卸载条件下,煤岩破坏按体积变化分为扩容性破坏和压缩性破坏,按破坏形式分为块状剪切型和不规则网状型;三轴应力影响下经过冻融的煤岩力学性质进一步发生改变,内部结构破坏明显,峰值抗压强度与内摩擦角均减小,应变程度增大,致裂效果明显,利于瓦斯抽采,并抑制煤岩扩容。研究结果可为液氮冻融技术在提高瓦斯抽采效率和解决煤岩扩容安全问题的上的应用提供理论基础。
In order to investigate the deformation characteristics of preheated freeze-thaw coal rock under triaxial stress,the experimental research on triaxial unloading of coal rock before and after liquid nitrogen freeze-thaw was carried out.The preheated drying and liquid nitrogen freeze-thaw pretreatment after preheated drying were conducted on coal rock by using a triaxial servo test system for coal rock with graphical measurement function,and the coal rock damage evolution and mechanical characteristics were investigated.The results show that the four stages summarizing the coal rock expansion process are compression stage,expansion start stage,expansion acceleration stage and expansion destruction stage.Under different initial confining pressure unloading conditions,the coal rock damage is divided into expansion damage and compression damage according to volume change,and into block shear type and irregular mesh type according to damage form.Under the influence of triaxial stress,the mechanical properties of freeze-thawed coal rock are further changed,and the internal structural damage is obvious.The peak compressive strength and internal friction angle are reduced,the strain degree is increased,and the cracking effect is obvious,which facilitates the gas extraction and inhibits coal rock expansion.The results can provide a theoretical basis for the application of liquid nitrogen freeze-thaw technology in improving the efficiency of gas extraction and solving the safety problem of coal rock expansion.
作者
齐消寒
王品
刘阳
侯双荣
朱同光
QI Xiaohan;WANG Pin;LIU Yang;HOU Shuangrong;ZHU Tongguang(School of Safety Science and Engineering,Liaoning Technical University,Huludao Liaoning 125105,China;Key Laboratory of Mine Thermo-motive Disaster and Prevention,Ministry of Education,Huludao Liaoning 125105,China)
出处
《中国安全生产科学技术》
CAS
CSCD
北大核心
2023年第7期69-76,共8页
Journal of Safety Science and Technology
基金
国家自然科学基金项目(52274205)
教育部重点实验室开放基金项目(JSK202010)。
关键词
液氮冻融致裂
卸载
力学特性
三轴试验
liquid nitrogen freeze-thaw cracking
unloading
mechanical properties
triaxial test
