承压破碎煤体碎胀系数演变特征与机制
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摘要
利用自制的承压破碎煤体渗流及自燃测试装置,实验测试及分析了破碎煤体在应力、应力-温度、应力-水分不同条件下的碎胀系数的演变特征与机制。研究结果表明:(1)煤样随着应力增加,碎胀系数变化具有明显的阶段性,且随应力变化服从负指数变化规律;(2)在相同的轴压下,碎胀系数随温度升高而增加,热膨胀效应明显,说明采空区煤自燃的热效应将造成破碎煤体的碎胀系数增大,堆积更为松散;(3)当破碎煤体外在水分含量增加,在相同的轴压情况下,碎胀系数随外在水分增加而增加。说明随着采空区破碎煤体外在水分的增加,破碎煤体的碎胀系数将增大;(4)破碎煤体在应力、热膨胀及湿膨胀作用下,堆积体内部颗粒发生相对移动、二次破碎、颗粒自组织再堆积,致使应力-应变曲线发生变化,进而影响其碎胀系数。
Using the self-made testing device of coal seepage and spontaneous combustion of compacted broken coal,the evolution characteristics and mechanism of bulking coefficient of broken coal under different conditions of stress,stress-temperature,and stress-water were tested and analyzed.The results show that:(1) the bulking co-efficient of broken coal has obvious stage with the increase of stress,and the change rule of bulking coefficient under the stress meets with the negative exponent.(2) under the same axial compression,the bulking coefficient increases with the increase of temperature,and the thermal expansion effect is obvious,which indicates that the thermal effect of spontaneous combustion will increase the bulking coefficient and loose the accumulation of broken coal in gob.(3) when the water content increases in vitro of the broken coal,under the same axial com-pression,the bulking coefficient increases with the increase of external moisture,which shows that the broken coal bulking coefficient will increase with the increase of water.(4) under the action of stress,thermal expansion and wet expansion,the internal particles occur relatively moving in the accumulation body,secondary crushed and granular self-accumulation,which cause the stress-strain curve change,and the bulking coefficient affected.
Using the self-made testing device of coal seepage and spontaneous combustion of compacted broken coal,the evolution characteristics and mechanism of bulking coefficient of broken coal under different conditions of stress,stress-temperature,and stress-water were tested and analyzed.The results show that:(1) the bulking co-efficient of broken coal has obvious stage with the increase of stress,and the change rule of bulking coefficient under the stress meets with the negative exponent.(2) under the same axial compression,the bulking coefficient increases with the increase of temperature,and the thermal expansion effect is obvious,which indicates that the thermal effect of spontaneous combustion will increase the bulking coefficient and loose the accumulation of broken coal in gob.(3) when the water content increases in vitro of the broken coal,under the same axial com-pression,the bulking coefficient increases with the increase of external moisture,which shows that the broken coal bulking coefficient will increase with the increase of water.(4) under the action of stress,thermal expansion and wet expansion,the internal particles occur relatively moving in the accumulation body,secondary crushed and granular self-accumulation,which cause the stress-strain curve change,and the bulking coefficient affected.
引文
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[15]XIA T,ZHOU F,LIU J,et al.A fully coupled hydro-thermo-mechanical model for the spontaneous combustion of underground coal seams[J].Fuel,2014,125(125):106-115.
[2]缪协兴,茅献彪,胡光伟,等.岩石(煤)的碎胀与压实特性研究[J].实验力学,1997,12(3):394-399.MIAO Xiexing,MAO Xianbiao,HU Guangwei,et al.Research on broken expand and press solid characteristics of rocks and Coal[J].Journal of Experimental Mechanics,1997,12(3):394-399.
[3]刘卫群,缪协兴.破碎岩石渗透性的试验测定方法[J].实验力学,2003,18(1):57-61.LIU Weiqun,MIAO Xiexing.A testing method for determining the permeability of broken rock[J].Journal of Experimental Mechanics,2003,18(1):57-61.
[4]马占国,缪协兴,陈占清,等.破碎煤体渗透特性的试验研究[J].岩土力学,2009,30(4):985-988.MA Zhanguo,MIAO Xiexing,CHEN Zhanqing,et al.Experimental study of permeability of broken coal[J].Rock and Soil Mechanics,2009,30(4):985-988.
[5]苏承东,顾明,唐旭,等.煤层顶板破碎岩石压实特征的试验研究[J].岩石力学与工程学报,2012,31(1):18-27.SU Chengdong,GU Ming,TANG Xu,et al.Experiment study of compaction characteristics of crushed stones from coal seam roof[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(1):18-27.
[6]张吉雄.矸石直接充填综采岩层移动控制及其应用研究[D].徐州:中国矿业大学,2008.ZHANG Jixiong.Study on strata movement controlling by raw waste backfilling with fully-mechanized coal mining technology and its engineering applications[D].Xuzhou:China University of Mining and Technology,2008.
[7]蒋长宝,段敏克,尹光志,等.不同含水状态下含瓦斯原煤加卸载试验研究[J].煤炭学报,2016,41(9):2230-2237.JIANG Changbao,DUAN Minke,YIN Guangzhi,et al.Loading-unloading experiments of coal containing gas under the condition of different moisture contents[J].Journal of China Coal Society,2016,41(9):2230-2237.
[8]孟召平,李明生.深部温度、压力条件及其对砂岩力学性质的影响[J].岩石力学与工程学报,2006,25(6):1177-1181.MENG Zhaoping,LI Mingsheng.Temperature and pressure under deep conditions and their influences on mechanical properties of sandstone[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(6):1177-1181.
[9]李连崇,唐春安,梁正召.考虑岩体碎胀效应的采场覆岩冒落规律分析[J].岩土力学,2010,31(11):3531-3541.LI Lianchong,TANG Chun’an,LIANG Zhengzhao.Investigation on overburden strata collapse around coal face considering effect of broken expansion of rock[J].Rock and Soil Mechanics,2010,31(11):3531-3541.
[10]梁冰,汪北方,姜利国,等.浅埋采空区垮落岩体碎胀特性研究[J].中国矿业大学学报,2016,45(3):475-483.LIANG Bing,WANG Beifang,JIANG Liguo,et al.Broken expand properties of caving rock in shallow buried goaf[J].Journal of China University of Mining&Technology,2016,45(3):475-482.
[11]汪北方,梁冰,姜利国,等.采空区垮落岩体空隙储水分形计算及应用研究[J].岩石力学与工程学报,2015,34(7):1444-1451.WANG Beifang,LIANG Bing,JIANG Liguo,et al.Fractal calculation and application of water storage in void of caving rock in the goaf[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(7):1444-1451.
[12]李树刚,钱鸣高.综放采空区冒落特征及瓦斯流态[J].矿山压力与顶板管理,1997,3(4):76-78.LI Shugang,QIAN Minggao.Features of fallen rock and methane flow characteristics in gob of fully-mechanized working-face with top-coal caving Ground[J].Pressure and Strata Control,1997,3(4):76-78.
[13]余明高,晁江坤,褚廷湘,等.承压破碎煤体渗透特性参数演化实验研究[J].煤炭学报,2017,42(4):916-922.YU Minggao,CHAO Jiangkun,CHU Tingxiang,et al.Experimental study on permeability parameter evolution of pressure-bear broken coal[J].Journal of China Coal Society,2017,42(4):916-922.
[14]XIA T,WANG X,ZHOU F,et al.Evolution of coal self-heating processes in longwall gob areas[J].International Journal of Heat and Mass Transfer,2015,86:861-868.
[15]XIA T,ZHOU F,LIU J,et al.A fully coupled hydro-thermo-mechanical model for the spontaneous combustion of underground coal seams[J].Fuel,2014,125(125):106-115.