易自燃煤氧化的力学特性  

Mechanical properties of spontaneous combustion coal oxidation

作　　者：潘荣锟[1,3] 马智会 余明高[5] 晁江坤[1] 马智勇 贾海林[1] 李聪 PAN Rongkun;MA Zhihui;YU Minggao;CHAO Jiangkun;MA Zhiyong;JIA Hailin;LI Cong(College of Safety Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China;School of Chemistry&Environmental Engineering,Sichuan University of Science&Engineering,Zigong 643000,China;State Collaborative Innovation Center of Coal Work Safety and Clean-efficiency Utilization,Henan Polytechnic University,Jiaozuo 454000,China;State Key Laboratory of Coal Resources in Western China,Xi’an University of Science&Technology,Xi’an 710054,China;State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;CCTEG Chongqing Research Institute,Chongqing 400037,China)

机构地区：[1]河南理工大学安全科学与工程学院,河南焦作454000 [2]四川轻化工大学化学与环境工程学院,四川自贡643000 [3]河南理工大学煤炭安全生产与清洁高效利用省部共建协同创新中心,河南焦作454000 [4]西安科技大学西部煤炭绿色开发国家重点实验室,陕西西安710054 [5]重庆大学煤矿灾害动力学与控制国家重点实验室,重庆400044 [6]中煤科工集团重庆研究院有限公司,重庆400037

出　　处：《煤炭学报》2021年第9期2949-2964,共16页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(51674103,51304070,51574111)。

摘　　要：为了研究易自燃煤体氧化后的力学特性变化,通过程序升温和热重实验获得煤氧化过程中的特征温度,并对煤样进行氧化处理;通过测试煤氧化前后的波速,得出氧化后煤体的损伤因子;通过单轴压缩实验,分析不同氧化煤的力学参数变化规律;通过建立氧化煤受力模型,分析不同氧化煤力学特性的差异并对典型工况研究。研究表明:①原煤和70,135,200和265℃氧化后煤样的平均纵波波速分别为1642,1416,1261,870和557 m/s,不同氧化煤的损伤因子平均值依次为0.19,0.43,0.72和0.86,随着氧化程度加深,波速降低,损伤因子变大;②原煤应力-应变曲线表现出较好的线性特征,其压密阶段和屈服阶段不明显;随着氧化程度加深,氧化煤应力-应变曲线压密阶段和屈服阶段越明显,多峰效应越显著,峰后台阶跌落效应越突出,且峰后存在明显残余强度,其塑性增强;③随着氧化加深,抗压强度从16.36 MPa降至4.10 MPa,弹性模量从3.779降至0.437,割线模量从2.05降至0.19,初始模量从0.609降至0.082,泊松比从0.37降至0.25;氧化对煤体的抗压强度影响最明显,其软化系数从0.89降低至0.25,并提出了“氧化煤动态工程强度”的概念;④随着氧化程度的增加,煤样的峰值应变和压密阶段最大轴应变逐渐增加,压缩阶段最大轴应变与峰值应变比值越来越大,当氧化程度达到265℃后,其比值近50%;⑤随着氧化程度的加深,煤样的破坏形式趋复杂化,破坏后的完整性变差,破坏后脱落的碎煤及煤粉增多,并伴随产生“起皮”现象;⑥氧化煤体由外向内划分为强氧化区、弱氧化区和未氧化区,并建立了氧化煤体受力模型,计算得出70,135,200和265℃氧化后的煤样未氧化区域直径为44.44,37.24,16.84和0.06 mm,分析了氧化煤体力学性质差异机制,并对典型工况进行了数值模拟分析。To study the changes in the mechanical properties of spontaneous combustion coal after oxidation,the characteristic temperatures in the process of coal oxidation were obtained by temperature programmed and thermogravimetric experiments,and the coal samples were oxidized.The damage factor of coal body after oxidation was obtained by testing the wave velocity of coal samples before and after oxidation.Through uniaxial compression test,the change law of mechanical parameters of different oxidized coal was analyzed.Through the establishment of the force model of oxidized coal,the difference of the mechanical properties of different oxidized coal was analyzed and the typical working conditions were studied.Through the above experimental study,the following results were obtained:①The average longitudinal wave velocities of raw coal and coal samples after oxidation at 70,135,200 and 265℃are 1642,1416,1261,870 and 557 m/s,respectively.The average values of damage factors of coal with different oxidation degrees are 0.19,0.43,0.72 and 0.86,respectively.With the increase of oxidation degree,the wave velocity decreases and the damage factor increases.②The stress-strain curve of raw coal shows good linear characteristics,and its compaction stage and yield stage are not obvious.With the increase of oxidation degree,the more obvious the compression stage and yield stage of the stress-strain curve of oxidized coal,the more obvious the multi peak effect,the more prominent the step drop effect behind the peak,and the obvious residual strength after the peak,and the plasticity of the oxidized coal increased.③With the increase of oxidation degree,compressive strength decreases from 16.36 MPa to 4.10 MPa,average modulus decreases from^(3).779 to 0.437,secant modulus decreases from 2.05 to 0.19,initial modulus decreases from 0.609 to 0.082,Poisson’s ratio decreases from 0.37 to 0.25.Oxidation has the most obvious effect on the compressive strength of coal,and its softening coefficient decreases from 0.89 to 0.25.The concept

关 键 词：易自燃煤 纵波波速 单轴压缩 力学特性 破坏特征 

分 类 号：TD313[矿业工程—矿井建设]