两种pH水环境干、湿循环作用对泥质砂岩的侵蚀研究
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摘要
选取三峡库区某边坡的泥质砂岩为研究对象,分别对pH=3和pH=7溶液下干、湿循环作用的泥质砂岩进行电镜扫描试验(SEM)、4种围压下的三轴压缩试验,通过MATLAB软件处理得到不同pH值和干、湿循环次数下SEM图像的骨架面积比和分形维数。研究表明:在相同的干、湿循环次数下,pH=3酸性环境下的分形维数比p H=7的要大;分形维数与吸水率成正比例相关;与骨架面积、凝聚力成反比例相关;泥质砂岩在干、湿循环作用下的临界骨架面积比为0.55左右;提出了泥质砂岩在干、湿循环作用下的侵蚀度概念,计算并拟合了泥质砂岩的侵蚀度随干、湿循环次数变化的关系曲线;推导出凝聚力的损伤变量公式,为研究不同pH水环境对岩石的侵蚀作用提供参考依据。
Argillaceous sandstone from a slope in Three Gorges Reservoir is investigated. A series of tests including triaxial compression test under four confining pressures, scanning electron microscope(SEM) is conducted on the sandstone samples subjected to cyclic wetting-drying in different p H conditions(p H=3, p H=7). The area ratio of skeleton and fractal dimension of images obtained by SEM under different p H conditions and different times of dry-wet cycle is obtained by MATLAB. The study shows that when samples suffer the same times of dry-wet cycle, the fractal dimension in acidic conditions(p H=3) is bigger than that in neutral conditions(p H=7). Also, it is indicated that the fractal dimension is proportion to water absorption rate and inversely proportion to skeleton area and cohesion. And the critical area ratio of skeleton of argillaceous sandstone subjected to alternation of wetting and drying is calculated to be 0.55. A concept of erosion degree is defined for argillaceous sandstone subjected to dry-wet cycles. Then a relation curve between the erosion degree of argillaceous sandstone and times of dry-wet cycle is obtained by fitting. Damage variable formula of cohesive force is derived. The study results provide theoretical basis for erosion of argillaceous sandstone in different p H conditions.
Argillaceous sandstone from a slope in Three Gorges Reservoir is investigated. A series of tests including triaxial compression test under four confining pressures, scanning electron microscope(SEM) is conducted on the sandstone samples subjected to cyclic wetting-drying in different p H conditions(p H=3, p H=7). The area ratio of skeleton and fractal dimension of images obtained by SEM under different p H conditions and different times of dry-wet cycle is obtained by MATLAB. The study shows that when samples suffer the same times of dry-wet cycle, the fractal dimension in acidic conditions(p H=3) is bigger than that in neutral conditions(p H=7). Also, it is indicated that the fractal dimension is proportion to water absorption rate and inversely proportion to skeleton area and cohesion. And the critical area ratio of skeleton of argillaceous sandstone subjected to alternation of wetting and drying is calculated to be 0.55. A concept of erosion degree is defined for argillaceous sandstone subjected to dry-wet cycles. Then a relation curve between the erosion degree of argillaceous sandstone and times of dry-wet cycle is obtained by fitting. Damage variable formula of cohesive force is derived. The study results provide theoretical basis for erosion of argillaceous sandstone in different p H conditions.
引文
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[20]刘传孝,蒋金泉,刘福胜,等.岩石材料微、细、宏观断裂机制尺度效应的分形研究[J].岩土力学,2008,29(10):2619-2622.LIU Chuan-xiao,JIANG Jin-quan,LIU Fu-sheng,et al.Fractal study of scale effect in microscopic,mesoscopic and macroscopic states for fracture mechanism of rock materials[J].Rock and Soil Mechanics,2008,29(10):2619-2622.
[21]中华人民共和国国家标准编写组.GB/T50266-2013工程岩体试验方法标准[S].北京:中国计划出版社,2013.The National Standards Compilation Group of People’s Republic of China.GB/T50266-2013 Standard for tests method of engineering rock masses[S].Beijing:China Planning Press,2013.
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[2]龚壁卫,周小文,周武华.干-湿循环过程中吸力与强度关系研究[J].岩土工程学报,2006,28(2):207-209.GONG Bi-wei,ZHOU Xiao-wen,ZHOU Wu-hua.Test on suction and strength of expansive soil in a desorption-absorption cycle of moisture[J].Chinese Journal of Geotechnical Engineering,2006,28(2):207-209.
[3]RIEMER.Landslides and reservoirs[C]//Proceedings of the 6th International Symposium Landslides.Rotterdam:A.A.Balkema,1995,1973-2004.
[4]HALE P A,SHAKOOR A.A laboratory investigation of the effects of cyclic heating and cooling,wetting and drying,and freezing and thawing on the compressive strength of selected sandstones[J].Environmental and Engineering Geoscience,2003,9(2):117-130.
[5]邓华锋,李建林,王孔伟,等.饱和-风干循环过程中砂岩次生孔隙率变化规律研究[J].岩土力学,2012,33(2):483-488.DENG Hua-feng,LI Jian-lin,WANG Kong-wei,et al.Research on secondary porosity changing law of sandstone under saturation-air dry cycles[J].Rock and Soil Mechanics,2012,33(2):483-488.
[6]邓华锋,原先凡,李建林,等.饱水度对砂岩纵波波速及强度影响的试验研究[J].岩石力学与工程学报,2013,32(8):1626-1631.DENG Hua-feng,YUAN Xian-fan,LI Jian-lin,et al.Experimental research on influence of saturation degree on sandstone longitudinal wave velocity and strength[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(8):1626-1631.
[7]张梁.酸性环境干、湿交替作用下泥质砂岩宏细观损伤特性研究[D].重庆:重庆大学,2014.ZHANG Liang.Study on macro-meso damage characteristics of argillaceous sandstone under dry-wet cycle in acidic condition[D].Chongqing:Chongqing University,2014.
[8]傅晏.干、湿循环水岩相互作用下岩石劣化机制研究[D].重庆:重庆大学,2010.FU Yan.Study on water-rock interaction with the cyclic drying-wetting effect on rock[D].Chongqing:Chongqing University,2010.
[9]WANG Wei-xing.Rock fracture network image analysis[J].Proceedings of the 6th World Congress on Intelligent Control and Automation,2006,2:9827-9830.
[10]PHAM C K,YAMANO K.An edge extraction method for color image using multiple-valued LOG filter and color space[C]//6th IEEE/ACIS International Conference on Computer and Information Science.[S.l.]:[s.n.],2007.
[11]张志,董福安,伍友利.二维灰度图像的分形维数计算[J].计算机应用,2005,25(12):2853-2867.ZHANG Zhi,DONG Fu-an,WU You-li.Estimation of fractal dimension for 2-D gray image[J].Computer Applications,2005,25(12):2853-2867.
[12]周翠英,牟春梅.软土破裂面的微观结构特征与强度的关系[J].岩土工程学报,2005,27(10):1137-1141.ZHOU Cui-ying,MU Chun-mei.Relationship between micro-structural characters of fracture surface and strength of soft clay[J].Chinese Journal of Geotechnical Engineering,2005,27(10):1137-1141.
[13]许姜严.基于小波的岩石节理裂隙图像处理[D].成都:电子科技大学,2010.XU Jiang-Yan.Rock fracture image processing based on wavelet analysis[D].Chengdu:University of Electronic Science and Technology of China,2010.
[14]王成虎,王红才,刘立鹏,等.高温对玄武质凝灰岩力学性能的影响及其机制分析[J].岩土工程学报,2012,34(10):1827-1835.WANG Cheng-hu,WANG Hong-cai,LIU Li-peng,et al.Effects of high temperatures on mechanical performance of basaltic tuff and mechanism analysis[J].Chinese Journal of Geotechnical Engineering,2012,34(10):1827-1835.
[15]杨仁树,王雁冰,薛华俊,等.切缝药包爆破岩石爆生裂纹断面的SEM试验[J].中国矿业大学学报,2013,42(3):337-341.YANG Ren-shu,WANG Yan-bing,XUE Hua-jun,et al.SEM experiment of rock crack cross section morphology after explosion fracturing with slotted cartridge[J].Journal of China University of Mining&Technology,2013,42(3):337-341.
[16]左婧,徐卫亚,王环玲,等.岩石电镜扫描图像的分形特征研究[J].三峡大学学报(自然科学版),2014,36(2):72-76.ZUO Jing,XU Wei-ya,WANG Huan-ling,et al.Fractal analysis of SEM image for rocks[J].Journal of China Three Gorges University(Natural Sciences),2014,36(2):72-76.
[17]张俊然,许强,孙德安.多次干、湿循环后土-水特征曲线的模拟[J].岩土力学.2014,35(3):689-695.ZHANG Jun-ran,XU Qiang,SUN De-an.Simulation of soil-water characteristic curves during drying and wetting cycles[J].Rock and Soil Mechanics,2014,35(3):689-695.
[18]穆坤,孔令伟,张先伟,等.红黏土工程性状的干湿循环效应试验研究[J].岩土力学,2016,37(8):2247-2253.MU Kun,KONG Ling-wei,ZHANG Xian-wei,et al.Experimental investigation on engineering behaviors of red clay under effect of wetting-drying cycles[J].Rock and Soil Mechanics,2016,37(8):2247-2253.
[19]谈云志,胡莫珍,周玮韬,等.荷载-干湿循环共同作用下泥岩的压缩特性[J].岩土力学,2016,37(8):2165-2171.TAN Yun-zhi,HU Mo-zhen,ZHOU Wei-tao,et al.Effects of drying-wetting cycle and loading on compressive property of mudstone[J].Rock and Soil Mechanics,2016,37(8):2165-2171.
[20]刘传孝,蒋金泉,刘福胜,等.岩石材料微、细、宏观断裂机制尺度效应的分形研究[J].岩土力学,2008,29(10):2619-2622.LIU Chuan-xiao,JIANG Jin-quan,LIU Fu-sheng,et al.Fractal study of scale effect in microscopic,mesoscopic and macroscopic states for fracture mechanism of rock materials[J].Rock and Soil Mechanics,2008,29(10):2619-2622.
[21]中华人民共和国国家标准编写组.GB/T50266-2013工程岩体试验方法标准[S].北京:中国计划出版社,2013.The National Standards Compilation Group of People’s Republic of China.GB/T50266-2013 Standard for tests method of engineering rock masses[S].Beijing:China Planning Press,2013.
[22]中华人民共和国行业标准编写组.SL264-2001水利水电工程岩石试验规程[S].北京:中国水利水电出版社,2001.The Professional Standard Compilation Group of People's Republic of China.SL264-2001 Specifications for rock tests in water conservancy and hydroelectric engineering[S].Beijing:China Water Power Press,2001.