基于数字图像测量技术的粉状煤系土微观结构分形特性分析
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摘要
以武深高速广东段沿线的粉状煤系土为研究对象,利用环境扫描电镜技术(ESEM)获得了不同含水率直剪试验后粉状煤系土剪切面的微观结构SEM图像;结合MATLAB及Image Pro Plus(IPP)软件,对剪切面微观结构特征进行了分析;基于分形理论,建立了煤系土的分形模型,求出了二维空间内煤系土孔隙轮廓分维数、孔隙数量～孔径分布分维数。结果表明:煤系土微观结构多为片状颗粒集合体,接触关系主要为面-面接触和面-边接触;随着含水率的增加,剪切面粗糙度先增加后减小,力学强度参数先增大后减小,转折点在最优含水率附近(10%～15%之间);煤系土微观结构具有明显的分形特征,可用孔隙等效面积-等效周长分形模型、孔隙数量～孔径分布分形模型描述,其分维数介于1～2。
Taking powdery coal-bearing soil along the Guangdong district of Wushen Expressway as research object, the SEM images of powdery coal-bearing soil microstructure were obtained by using Environmental Scanning Electron Microscopy(ESEM) under different water content after direct shear test. The microstructural morphology characterization of shear surface is analyzed by MATLAB and Image Pro-Plus(IPP) software. Based on fractal theory, the fractal model of coal-bearing soil microstructure is established, and the fractal dimensions of pore profile and number and size distribution of pores of coal-bearing soil are obtained in two-dimensional space.The results show that the microstructure of coal-bearing soil is schistose aggregated particles. The contact relationship is mainly surface-surface contact and face-side contact. The shape of the flaky granule aggregated body is irregular and the orientation is not obvious. The shape of pore is anisometric and slotted. With the increase of water content, the roughness and fluctuation degree of the shear surface first increase and then decrease, the shearing strength parameters also increases first and then decreases. The turning point is near the optimum moisture content(between 10% and 15%). The microstructure of coal-bearing soil has obvious fractal characteristics. It is described by the fractal model of the equivalent area and equivalent perimeter of pores and fractal model of pore number and pore diameter distribution, and the fractal dimension is between 1 and 2 in 2D space.
Taking powdery coal-bearing soil along the Guangdong district of Wushen Expressway as research object, the SEM images of powdery coal-bearing soil microstructure were obtained by using Environmental Scanning Electron Microscopy(ESEM) under different water content after direct shear test. The microstructural morphology characterization of shear surface is analyzed by MATLAB and Image Pro-Plus(IPP) software. Based on fractal theory, the fractal model of coal-bearing soil microstructure is established, and the fractal dimensions of pore profile and number and size distribution of pores of coal-bearing soil are obtained in two-dimensional space.The results show that the microstructure of coal-bearing soil is schistose aggregated particles. The contact relationship is mainly surface-surface contact and face-side contact. The shape of the flaky granule aggregated body is irregular and the orientation is not obvious. The shape of pore is anisometric and slotted. With the increase of water content, the roughness and fluctuation degree of the shear surface first increase and then decrease, the shearing strength parameters also increases first and then decreases. The turning point is near the optimum moisture content(between 10% and 15%). The microstructure of coal-bearing soil has obvious fractal characteristics. It is described by the fractal model of the equivalent area and equivalent perimeter of pores and fractal model of pore number and pore diameter distribution, and the fractal dimension is between 1 and 2 in 2D space.
引文
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[24] Yu B M, Li J H. Fractal dimensions for unsaturated porous media. Fractals, 2004, 12(1):12-22.
[25]许勇,张季超,李伍平.饱和软土微结构分形特征的试验研究[J].岩土力学,2007,28(增刊):49-52.
[26] Xiao BQ, Fan JT, Ding F. Prediction of relative permeability of unsaturated porous media based on fractal theory and Monte Carlo simulation[J]. Energy Fuels, 2012, 26(11):6971-6978.
[27] Liu R, Jiang Y, Li B, et al. A fractal model for characterizing fluid flow in fractured rock masses based on randomly distributed rock fracture networks[J]. Comput. Geotech.,2015, 65:45-55.
[28] Pia G, Corcione CE, Striani R et al. Thermal conductivity of porous stones treated with UV light-cured hybrid organicinorganic methacrylic-based coating[J]. Experimental and fractal modeling procedure. Prog. Org. Coat, 2016, 94:105-115.
[29]谭之东,梁收运,周自强,等.基于SEM图像的分形维数与泥岩颜色关系—以崆峒山国家地质公园白垩系斑马状泥岩为例[J].地质调查与研究,2018,41(2):153-160.
[2] Zhang J C, Shen B H. Coal mining under aquifers in China:a case study[J]. Int. J. Rock Mech. Min. Sci., 2004, 41(4),629-639.
[3] Majdi A, Hassani F P, Nasiri M Y. Prediction of the height of destressed zone above the mined panel roof in longwall coal mining[J]. Int. J. Coal Geol., 2012, 98, 62-72.
[4] Meng Z P, Shi X C, Li G Q. Deformation, failure and permeability of coal-bearing strata during longwall mining[J]. Engineering Geology, 2016, 208:69-80.
[5]胡昕,洪宝宁,杜强,等.含水率对煤系土抗剪强度的影响[J].岩土力学,2009,30(8):2291-2294.
[6]周邦艮,褚兰晢,王爱华.广梧高速公路煤系土抗剪强度特性试验研究[J].路基工程,2009,(2):119-120.
[7]祝磊,洪宝宁.粉状煤系土的物理力学特性[J].岩土力学,2009,30(5):1317-1322.
[8]杨文军,洪宝宁,周邦良,等.砾状煤系土改良性能的试验研究[J].岩土力学,2012,33(1):96-102.
[9]李辉,刘顺青.重塑红黏土和粉状煤系土的水敏感性比较研究[J].中山大学学报(自然科学版),2015,54(6):89-93.
[10]姚环.黏性土微观结构与力学性质关系的研究[J].福州大学学报,1995,23(4):113-118.
[11]胡瑞林,王思敬.21世纪工程地质学生长点:土体微结构力学[J].水文地质工程地质,1999,(4):5-8.
[12] Al-Rawas A A, McGown A. Microstructure of Omani expansive soils[J]. Can. Geotech. J., 1999, 36(2):272-290.
[13]李向全,胡瑞林,张莉.软土固结过程中的微结构变化特征[J].地学前缘,2000,7(1):147-152.
[14] Horpibulsuk S, Rachan R, Chinkulkijniwat A, Raksachon Y, Suddeepong A. Analysis of strength development in cement-stabilized silty clay from microstructural considerations[J]. Constr. Build. Mater., 2010, 24:2011-2021.
[15] Aldaood A, Bouasker M, Al-Mukhtar M. Impact of wettingdrying cycles on the microstructure and mechanical properties of lime-stabilized gypseous soils[J]. Engineering Geology, 2014, 174:11-21.
[16] Reimer I. Scanning Electron Microscopy[M]. New York:Springer, 1995:136.
[17] Harnson C, Park M, Chaikin P M, et al. Layer by layer imaging of diblock copolymer films with a scanning electron microscope[J]. Polymer, 1998, 39(13):2733-2745.
[18] Lyubenova T S, Matteucci F, Costa A, et al. Ceramic pigments with sphene structure obtained by both spray and freeze-drying techniques[J]. Powder Technology, 2009, 193(1):1-5.
[19] Mandelbrot B B. The Fractal Geometry of Nature[M]. San Francisco:W.H. Freeman, 1982.
[20] Katz A J, Thompson A H. Fractal sandstone pores:Implications for conductivity and pore formation[J]. Phys Rev Lett.1985, 54:1325-1328.
[21] Feder J. Fractals[M]. Plenum Press New York, 1988, 1-199.
[22] Turcotte D L. Fractals and fragmentation[J]. Journal of Geophysical Research, 1986, 91(B2):1921-1926.
[23] Tyler SW, Wheatcraft SW. Application of fractal mathematics to soil water retention estimation[J]. Soil Sci. Soc. Am.J., 1989, 53:987-996.
[24] Yu B M, Li J H. Fractal dimensions for unsaturated porous media. Fractals, 2004, 12(1):12-22.
[25]许勇,张季超,李伍平.饱和软土微结构分形特征的试验研究[J].岩土力学,2007,28(增刊):49-52.
[26] Xiao BQ, Fan JT, Ding F. Prediction of relative permeability of unsaturated porous media based on fractal theory and Monte Carlo simulation[J]. Energy Fuels, 2012, 26(11):6971-6978.
[27] Liu R, Jiang Y, Li B, et al. A fractal model for characterizing fluid flow in fractured rock masses based on randomly distributed rock fracture networks[J]. Comput. Geotech.,2015, 65:45-55.
[28] Pia G, Corcione CE, Striani R et al. Thermal conductivity of porous stones treated with UV light-cured hybrid organicinorganic methacrylic-based coating[J]. Experimental and fractal modeling procedure. Prog. Org. Coat, 2016, 94:105-115.
[29]谭之东,梁收运,周自强,等.基于SEM图像的分形维数与泥岩颜色关系—以崆峒山国家地质公园白垩系斑马状泥岩为例[J].地质调查与研究,2018,41(2):153-160.