低温冻结石门揭煤煤体未冻水含量变化特征
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摘要
为探究煤在低温冻结石门揭煤过程中煤体未冻水含量的变化,采用低场核磁共振技术对褐煤、烟煤和无烟煤共3种类型的饱和试样进行测试,同时结合T2谱图从微观角度分析了冻融过程中未冻水在煤孔隙内的赋存分布情况和变化特征。试验结果表明:3种煤样在冻融过程中,其未冻水含量随温度变化呈现出相似的特征:在冻结过程中,可划分为3个阶段,波动段、急剧下降段和稳定段;在融化过程中,可划分为2个阶段,稳定增加段和急剧增加段,并且有明显的滞后现象;在冻结时,大孔隙内的水先开始相变成冰,然后是中孔,最后微、小孔内的水才开始明显下降;在融化时,微、小孔内的冰先开始融化;在同样的冻结温度区间内,烟煤和无烟煤中未冻水含量的降低程度要小于褐煤。
In order to discover the unfrozen water content variation of the coal from the low temperature frozen cross-cut passed through seam,a low-field nuclear magnetic resonance technology was applied to the test on three type saturated coal samples of the lignite,bituminous coal and anthracite coal. Meanwhile,in combination with the T2 spectrogram,from a microcosmic view,the paper had an analysis on the unfrozen water distribution and variation in coal pores in the freezing-thawing process. The experimental result showed that in the freezing-thawing process of the three different type coal samples,with the temperature varied,the unfrozen water would appear similar characteristics. In the freezing process,the process could be divided into three stages and they were a fluctuating stage,steeply reduced stage and stable stage. In the thawing process,the process could be divided into two stages and they were a stable increased stage and steep increased stage with an obvious lagging phenomenon. During the freezing period,the water in the big pores would firstly have a phase transition and then be in ice. Late the water in the medium pores,micro pores and small pores would finally be reduced obviously. In the thawing period,the ices in the micro and small pores would firstly be thaw. Within the same freezing temperature zone,the unfrozen water contents in the bituminous coal and anthracite coal would reduce less than the lignite.
In order to discover the unfrozen water content variation of the coal from the low temperature frozen cross-cut passed through seam,a low-field nuclear magnetic resonance technology was applied to the test on three type saturated coal samples of the lignite,bituminous coal and anthracite coal. Meanwhile,in combination with the T2 spectrogram,from a microcosmic view,the paper had an analysis on the unfrozen water distribution and variation in coal pores in the freezing-thawing process. The experimental result showed that in the freezing-thawing process of the three different type coal samples,with the temperature varied,the unfrozen water would appear similar characteristics. In the freezing process,the process could be divided into three stages and they were a fluctuating stage,steeply reduced stage and stable stage. In the thawing process,the process could be divided into two stages and they were a stable increased stage and steep increased stage with an obvious lagging phenomenon. During the freezing period,the water in the big pores would firstly have a phase transition and then be in ice. Late the water in the medium pores,micro pores and small pores would finally be reduced obviously. In the thawing period,the ices in the micro and small pores would firstly be thaw. Within the same freezing temperature zone,the unfrozen water contents in the bituminous coal and anthracite coal would reduce less than the lignite.
引文
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[19]卢星航,史海滨,李瑞平,等.基于NMR技术的盐渍化冻融土壤未冻水及孔隙水含量试验研究[J].水土保持学报,2017,31(2):111-116.LU Xinghang,SHI Haibin,LI Ruiping,et al.NMR based research on unfrozen water and pore water content in saline freezing-thawing soils[J]. Journal of Soil and Water Conservation,2017,31(2):111-116.
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[21] QIN Lei,ZHAI Cheng,LIU Shimin,et al.Changes in the petrophysical properties of coal subjected to liquid nitrogen freeze-thaw-A nuclear magnetic resonance investigation[J].Fuel,2017,194:102-114.
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[23]翟成,孙勇.低温循环致裂煤体孔隙结构演化规律试验研究[J].煤炭科学技术,2017,45(6):24-29.ZHAI Cheng,SUN Yong.Experimental study on evolution of pore structure incoal after cyclic cryogenic fracturing[J].Coal Science and Technology,2017,45(6):24-29.
[24]泰斯A R,奥利丰特J L,朱元林,等.用脉冲核磁共振法及物理解吸试验测定的冻土中冰和未冻水之间的关系[J].冰川冻土,1983,5(2):37-46.TICE A R,OPIPHANT J L,ZHU Yuanlin,et al.Relationship between the ice and unfrozen water phases in frozen soils as determined by pulsed nuclear resonance and physical desorption data[J].Journal of Glaciology and Geocryology,1983,5(2):37-39.
[25] Bittelli M,Flury M,CAMPBELL,et al. A thermodiel-ectric analyzer to measure the freezing and moisture characteristic of porous media[J]. Water Resources Research, 2003,39:1041-1042.
[26] CAI YD,LIU DM,PAN Z J,et al.Petro physical characterization of Chinese coal cores with heattreatment by nuclear magnetic resonance[J]. Fuel 2013,108:292-302.
[27] YAO Y B,LIU D M,CHEN Y,et al. Petrophysical cha-racterization of coals by low-field nuclearmag-netic resonance(NMR)[J].Fuel 2010,89(7):1371-1380.
[2]张铁岗.矿井瓦斯综合治理技术[M].北京:煤炭工业出版社,2001.
[3] YANG Wei,WANG Hao,LIN Baiquan,et al.Outburst me-chanism of tunnelling through coal seams and th-e safety strategy by using“strong-weak”coupling circle-layers[J].Tunnelling and Underground Space Technology,2018,74:107-118.
[4]冯涛,谢雄刚,刘辉,等.注液冻结法在石门揭煤中防突作用的可行性研究[J].煤炭学报,2010,35(6):937-941.FENG Tao,XIE Xionggang,LIU Hui,et al. Research on feasibility in preventing the coal and gas outburst by infecting liquid andfreezing in uncovering coal seam in cross-cut[J].Journal of China Coal Society,2010,35(6):937-941.
[5]谢雄刚.石门揭煤过程煤与瓦斯突出的注液冻结防治理论及技术研究[D].长沙:中南大学,2010.
[6]陈瑞杰,程国栋,李述训.人工地层冻结应用研究进展和展望[J].岩土工程学报,2000,22(1):26-27.CHEN Ruijie,CHENG Guodong,LI Shuxun. Devel-opment and prospect of research on applicationof artificial ground freezing[J].Chinese Journal of Geotechnical Engineering, 2000, 22(1):26-27.
[7]徐敩祖,王家澄,张立新.冻土物理学[M].北京:科学出版社,2001.
[8] LI Haipeng,YANG Zhaohui,WANG Jiahui.Unfrozen water content of permafrost during thawing by the capacitance technique[J].Cold Regions Science and Technology,2018,152:15-22.
[9] HUANG Shibing,LIU Quansheng,LIU Yanzhang,et al. Freezing strain model for estimating the unfrozen water content of saturated rock under low temperature[J]. International Journal of Geomechanics,2018,18(2):1-12.
[10] Tomzsz K A.Semi-empirical model for phase composition of water in clay-water systems[J].Cold Regions Science and Technology,2007,49(3):226-236.
[11]徐敩祖,奥利奋特J L,泰斯A R.土水势、未冻水含量和温度[J].冰川冻土,1985(1):1-14.XU Xiaozu,Oliphant J L,Tice A R. Soil water potential,unfrozen water content and temperature[J].Journal of Glaciology and Geocryology,1985(1):1-14.
[12] QIN Yinghong,ZHANG Jianming.Estimating the stability of unprotected embankment in warm and ice-rich permafrost region[J].Cold Regions Science and Technology,2009,61:65-71.
[13]冷毅飞,张喜发,杨凤学,等.冻土未冻水含量的量热法试验研究[J].岩土力学,2010,31(12):3758-3764.LENG Yifei,ZHANG Xifa,YANG Fengxue,et al. Ex-perimental research on unfrozen water content of frozen soils by calorimetry[J]. Rock and Soil Mechanics,2010,31(12):3758-3764.
[14]谭龙,韦昌富,田慧会,等.冻土未冻水含量的低场核磁共振试验研究[J].岩土力学,2015,36(6):1566-1572.TAN Long,WEI Changfu,TIAN Huihui,et al.Experimental study of unfrozen water content of frozen soils by lowfield nuclear magnetic resonance[J]. Rock and Soil Mechanics,2015,36(6):1566-1572.
[15]刘泉声,黄诗冰,康永水.低温饱和岩石未冻水含量与冻胀变形模型研究[J].岩石力学与工程学报,2016,35(10):2000-2012.LIU Quansheng,HUANG Shibing,KANG Yongshui. Study of unfrozen water content and frost heave model for saturated rock under low temperature[J]. Chinese Journal of Rock Mechanics and Engineering,2016,35(10):2000-2012.
[16] HUANG Shibing,LIU Quansheng,CHENG Aiping,et al.A fully coupled thermo-hydro-mechanical model including the determination of coupling parameters for freezing rock[J]. International Journal of Rock Mechanics and Mining Sciences,2018,103:205-214.
[17]刘慧,杨更社,叶万军.基于CT图像直方图技术的冻结岩石未冻水含量及损伤特性分析[J].冰川冻土,2015,37(6):1591-1598.LIU Hui,YANG Gengshe,YE Wanjun.Analysis of unfrozen water content and damage characteristics of frozen rock based on CT histogram Technology[J].Journal of Glaciology and Geocryology,2015,37(6):1591-1598.
[18] ZHAI C,Qin L,LIU SM,et al. Pore structure in coal:pore evolution after cryogenic freezing with cyclic liquid nitrogen injection and its implicateon on coalbed methane extraction[J].Energy&Fuels,2016,30(7):6009-6020.
[19]卢星航,史海滨,李瑞平,等.基于NMR技术的盐渍化冻融土壤未冻水及孔隙水含量试验研究[J].水土保持学报,2017,31(2):111-116.LU Xinghang,SHI Haibin,LI Ruiping,et al.NMR based research on unfrozen water and pore water content in saline freezing-thawing soils[J]. Journal of Soil and Water Conservation,2017,31(2):111-116.
[20] XU Jizhao,ZHAI Cheng,LIU Shimin,et al.Feasibility investigation of cryogenic effect from liquid carbon dioxide multi cycle fracturing technology in coalbed methane recovery[J].Fuel,2017,206:371-380.
[21] QIN Lei,ZHAI Cheng,LIU Shimin,et al.Changes in the petrophysical properties of coal subjected to liquid nitrogen freeze-thaw-A nuclear magnetic resonance investigation[J].Fuel,2017,194:102-114.
[22] XU Jizhao,ZHAI Cheng,LIU Shimin,et al.Pore variation of three different metamorphic coals by multiple freezing-thawing cycles of liquid CO2injection for coalbed methane recovery[J]. Fuel,2017,208:41-51.
[23]翟成,孙勇.低温循环致裂煤体孔隙结构演化规律试验研究[J].煤炭科学技术,2017,45(6):24-29.ZHAI Cheng,SUN Yong.Experimental study on evolution of pore structure incoal after cyclic cryogenic fracturing[J].Coal Science and Technology,2017,45(6):24-29.
[24]泰斯A R,奥利丰特J L,朱元林,等.用脉冲核磁共振法及物理解吸试验测定的冻土中冰和未冻水之间的关系[J].冰川冻土,1983,5(2):37-46.TICE A R,OPIPHANT J L,ZHU Yuanlin,et al.Relationship between the ice and unfrozen water phases in frozen soils as determined by pulsed nuclear resonance and physical desorption data[J].Journal of Glaciology and Geocryology,1983,5(2):37-39.
[25] Bittelli M,Flury M,CAMPBELL,et al. A thermodiel-ectric analyzer to measure the freezing and moisture characteristic of porous media[J]. Water Resources Research, 2003,39:1041-1042.
[26] CAI YD,LIU DM,PAN Z J,et al.Petro physical characterization of Chinese coal cores with heattreatment by nuclear magnetic resonance[J]. Fuel 2013,108:292-302.
[27] YAO Y B,LIU D M,CHEN Y,et al. Petrophysical cha-racterization of coals by low-field nuclearmag-netic resonance(NMR)[J].Fuel 2010,89(7):1371-1380.