固结条件下黏性土微观孔隙结构试验研究
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摘要
土体微观结构状态是控制土体稳定的重要因素,工程土体在宏观上表现出的复杂特性根本上取决于微结构的复杂性和不确定性。本文以德州市沉降区钻孔中黏性土层为研究对象,基于对电镜扫描图像的分析处理,从微观角度对不同深度黏性土的孔隙结构演化机制进行研究,并探讨土体初始结构状态对压缩性的制约关系。微观试验分析表明:固结荷载改变土体微结构类型,随着固结荷载增加,结构单元体由松散状态转变为团聚状态,土体密实度提高,孔隙面积减小。定量分析表明:固结压力将改变土体微结构要素,随着固结荷载增加,平均孔径减小、微小孔隙所占比例增加、孔隙形状不断调整最终趋于圆滑、集团化程度变高、土体定向性增强。上述试验为深入理解土体微观结构非线性问题,以及微观结构与宏观工程特性的相互作用机制提供了依据。
The microstructure state of soil is an important factor to control the stability of soil. The complex macroscopic characteristics of engineering soil are fundamentally determined by its complexity and uncertainty of microstructure. In this paper, taking the clay soil from the settlement area of Dezhou City as research object, based on the analysis and processing of scanning electron microscope images, the mechanism of pore structure evolution of clay soil taken from different depths was studied from the microscopic point of view. The constraint relation between the initial structure state and compressibility of soil was also discussed. Experimental results show that the consolidation load has changed the microstructure type of soil; with the increase of consolidation load, the structural units are converted from loose state to reunion state; the compactness of soil increases and the pore area decreases. Quantitative analysis shows that the consolidation pressure will change the micro-structural elements of soil. With the increase of consolidation load, the average pore size decreases and the proportion of micro-pores increases. The pore shape will eventually adjust to be smooth, and the degree of collectivization will increase, soil orientation enhanced. The above experiment provides an important basis for the further understanding of the nonlinear problem of soil microstructure and the interaction mechanism between microstructure and macroscopic engineering characteristics.
The microstructure state of soil is an important factor to control the stability of soil. The complex macroscopic characteristics of engineering soil are fundamentally determined by its complexity and uncertainty of microstructure. In this paper, taking the clay soil from the settlement area of Dezhou City as research object, based on the analysis and processing of scanning electron microscope images, the mechanism of pore structure evolution of clay soil taken from different depths was studied from the microscopic point of view. The constraint relation between the initial structure state and compressibility of soil was also discussed. Experimental results show that the consolidation load has changed the microstructure type of soil; with the increase of consolidation load, the structural units are converted from loose state to reunion state; the compactness of soil increases and the pore area decreases. Quantitative analysis shows that the consolidation pressure will change the micro-structural elements of soil. With the increase of consolidation load, the average pore size decreases and the proportion of micro-pores increases. The pore shape will eventually adjust to be smooth, and the degree of collectivization will increase, soil orientation enhanced. The above experiment provides an important basis for the further understanding of the nonlinear problem of soil microstructure and the interaction mechanism between microstructure and macroscopic engineering characteristics.
引文
[1] 谢海澜,武强,赵增敏,等.考虑非达西流的弱透水层固结计算[J].岩土力学,2007,28(5):1061-1065 (XIE Hailan,WU Qiang,ZHAO Zengmin,et al.Consolidation computation of aquitard considering non-Darcy flow[J].Rock and Soil Mechanics,2007,28 (5):1061-1065 (in Chinese))
[2] 沈珠江.土体结构性的数学模型——21世纪土力学的核心问题[J].岩土工程学报,1996,18(1):95-97 (SHEN Zhujiang.Mathematical model of soil structure-Core issues of soil mechanics in the 21st century [J].Chinese Journal of Geotechnical Engineering,1996,18(1):95-97 (in Chinese))
[3] 龚晓南,熊传祥,项可祥,等.粘土结构性对其力学性质的影响及形成原因分析[J].水利学报,2000,31(10):43-47 (GONG Xiaonan,XIONG Chuanxiang,XIANG Kexiang,et al.The formation of clay structure and its influence on mechanical characteristics of clay[J].Journal of Hydraulic Engineering,2000,31(10):43-47 (in Chinese))
[4] 施斌,姜洪涛.粘性土的微观结构分析技术研究[J].岩石力学与工程学报,2001,20(6):864-870 (SHI Bin,JIANG Hongtao.Research on the analysis techniques for clayey soil microstructure[J].Chinese Journal of Rock Mechanics and Engineering,2001,20(6):864-870 (in Chinese))
[5] 吴义祥.工程粘性土微观结构的定量评价[J].地球学报,1991,12(2):143-151 (WU Yixiang.Quantitative approach on micro-structure of engineering clay [J].Acta Geoscientica Sinica,1991,12(2):143-151 (in Chinese))
[6] 谢和平.分形几何及其在岩土力学中的应用[J].岩土工程学报,1992,14(1):14-24 (XIE Heping.Fractal geometry and its application to rock and soil materials[J].Chinese Journal of Geotechnical Engineering,1992,14(1):14-24(in Chinese))
[7] 沈珠江.结构性粘土的非线性损伤力学模型[J].水利水运工程学报,1993(3):247-255 (SHEN Zhujiang.A nonlinear damage model for structured clay[J].Hydro-Science and Engineering,1993(3):247-255 (in Chinese))
[8] 尚嘉兰,李廷芥.岩石细观损伤破坏的观测研究[J].实验力学,1999,14(3):373-383 (SHANG Jialan,LI Tingjie.Observation and study on meso-damage and fracture of rock[J].Journal of Experimental Mechanics,1999,14(3):373-383 (in Chinese))
[9] 薛茹,胡瑞林,毛灵涛.软土加固过程中微结构变化的分形研究[J].土木工程学报,2006,39(10):87-91 (XUE Ru,HU Ruilin,MAO Lingtao.Fractal study on the microstructure variation of soft soils in consolidation process[J].China Civil Engineering Journal,2006,39(10):87-91 (in Chinese))
[10] 张先伟,孔令伟.利用扫描电镜、压汞法、氮气吸附法评价近海黏土孔隙特征[J].岩土力学,2013(S2):134-142 (ZHANG Xianwei,KONG Lingwei.Study of pore characteristics of offshore clay by SEM and MIP and NA methods[J].Rock and Soil Mechanics,2013(S2):134-142 (in Chinese))
[11] 李妥德,谌壮丽.土样微观结构研究中的样品制备技术[J].水文地质工程地质,1985(2):41-45 (LI Tuode,CHEN Zhuangli.Technology of sample preparation in microstructure research of soil samples[J].Hydrogeology & Engineering Geology,1985(2):41-45 (in Chinese))
[12] 白冰,周健.扫描电子显微镜测试技术在岩土工程中的应用与进展[J].电子显微学报,2001,20(2):154-160 (BAI Bing,ZHOU Jian.The applications and advances of SEM in geotechnical engineering[J].Journal of Chinese Electron Microscopy Society,2001,20(2):154-160 (in Chinese))
[13] 唐朝生,施斌,王宝军.基于SEM土体微观结构研究中的影响因素分析[J].岩土工程学报,2008,30(4):560-565 (TANG Chaosheng,Shi Bin,WANG Baojun.Factors affecting analysis of soil microstructure using SEM[J].Chinese Journal of Geotechnical Engineering,2008,30(4):560-565(in Chinese))
[14] Liu C,Shi B,Zhou J,et al.Quantification and characterization of micro porosity by image processing,geometric measurement and statistical methods:Application on SEM images of clay materials[J].Applied Clay Science,2011,54(1):97-106.
[15] 张季如,祝杰,黄丽,等.固结条件下软黏土微观孔隙结构的演化及其分形描述[J].水利学报,2008,39(4):394-400 (ZHANG Jiru,ZHU Jie,HUANG Li,et al.Evolution of micro pore structure of soft clay and its fractal features under consolidation[J].Journal of Hydraulic Engineering,2008,39(4):394-400 (in Chinese))
[16] 周晖.珠江三角洲软土显微结构与渗流固结机理研究[D].华南理工大学,2013 (ZHOU Hui.Study on soft soil microstructure and mechanism of seepage and consolidation in Pearl River Delta[D].South China University of Technology,2013 (in Chinese))
[17] 毛灵涛,薛茹,安里千,等.软土孔隙微观结构的分形研究[J].中国矿业大学学报,2005,34(5):600-604 (MAO Lingtao,XUE Ru,AN Liqian,et al.Fractal approach on soft soil porosity microstructure[J].Journal of China University of Mining & Technology,2005,34(5):600-604 (in Chinese))
[18] 施斌.粘性土微观结构定向性的定量研究[J].地质学报,1997,71(1):36-44 (SHI Bin.Quantitative research on the orientation of microstructures of clayey soil [J].Acta Geologica Sinica,1997,71(1):36-44 (in Chinese))
[19] 胡瑞林.粘性土微结构定量模型及其工程地质特征研究[M].地质出版社,1995 (HU Ruilin.Quantitative microstructure models of clayey soils and their engineering behaviors[M].Geological Publishing House,1995 (in Chinese))
[2] 沈珠江.土体结构性的数学模型——21世纪土力学的核心问题[J].岩土工程学报,1996,18(1):95-97 (SHEN Zhujiang.Mathematical model of soil structure-Core issues of soil mechanics in the 21st century [J].Chinese Journal of Geotechnical Engineering,1996,18(1):95-97 (in Chinese))
[3] 龚晓南,熊传祥,项可祥,等.粘土结构性对其力学性质的影响及形成原因分析[J].水利学报,2000,31(10):43-47 (GONG Xiaonan,XIONG Chuanxiang,XIANG Kexiang,et al.The formation of clay structure and its influence on mechanical characteristics of clay[J].Journal of Hydraulic Engineering,2000,31(10):43-47 (in Chinese))
[4] 施斌,姜洪涛.粘性土的微观结构分析技术研究[J].岩石力学与工程学报,2001,20(6):864-870 (SHI Bin,JIANG Hongtao.Research on the analysis techniques for clayey soil microstructure[J].Chinese Journal of Rock Mechanics and Engineering,2001,20(6):864-870 (in Chinese))
[5] 吴义祥.工程粘性土微观结构的定量评价[J].地球学报,1991,12(2):143-151 (WU Yixiang.Quantitative approach on micro-structure of engineering clay [J].Acta Geoscientica Sinica,1991,12(2):143-151 (in Chinese))
[6] 谢和平.分形几何及其在岩土力学中的应用[J].岩土工程学报,1992,14(1):14-24 (XIE Heping.Fractal geometry and its application to rock and soil materials[J].Chinese Journal of Geotechnical Engineering,1992,14(1):14-24(in Chinese))
[7] 沈珠江.结构性粘土的非线性损伤力学模型[J].水利水运工程学报,1993(3):247-255 (SHEN Zhujiang.A nonlinear damage model for structured clay[J].Hydro-Science and Engineering,1993(3):247-255 (in Chinese))
[8] 尚嘉兰,李廷芥.岩石细观损伤破坏的观测研究[J].实验力学,1999,14(3):373-383 (SHANG Jialan,LI Tingjie.Observation and study on meso-damage and fracture of rock[J].Journal of Experimental Mechanics,1999,14(3):373-383 (in Chinese))
[9] 薛茹,胡瑞林,毛灵涛.软土加固过程中微结构变化的分形研究[J].土木工程学报,2006,39(10):87-91 (XUE Ru,HU Ruilin,MAO Lingtao.Fractal study on the microstructure variation of soft soils in consolidation process[J].China Civil Engineering Journal,2006,39(10):87-91 (in Chinese))
[10] 张先伟,孔令伟.利用扫描电镜、压汞法、氮气吸附法评价近海黏土孔隙特征[J].岩土力学,2013(S2):134-142 (ZHANG Xianwei,KONG Lingwei.Study of pore characteristics of offshore clay by SEM and MIP and NA methods[J].Rock and Soil Mechanics,2013(S2):134-142 (in Chinese))
[11] 李妥德,谌壮丽.土样微观结构研究中的样品制备技术[J].水文地质工程地质,1985(2):41-45 (LI Tuode,CHEN Zhuangli.Technology of sample preparation in microstructure research of soil samples[J].Hydrogeology & Engineering Geology,1985(2):41-45 (in Chinese))
[12] 白冰,周健.扫描电子显微镜测试技术在岩土工程中的应用与进展[J].电子显微学报,2001,20(2):154-160 (BAI Bing,ZHOU Jian.The applications and advances of SEM in geotechnical engineering[J].Journal of Chinese Electron Microscopy Society,2001,20(2):154-160 (in Chinese))
[13] 唐朝生,施斌,王宝军.基于SEM土体微观结构研究中的影响因素分析[J].岩土工程学报,2008,30(4):560-565 (TANG Chaosheng,Shi Bin,WANG Baojun.Factors affecting analysis of soil microstructure using SEM[J].Chinese Journal of Geotechnical Engineering,2008,30(4):560-565(in Chinese))
[14] Liu C,Shi B,Zhou J,et al.Quantification and characterization of micro porosity by image processing,geometric measurement and statistical methods:Application on SEM images of clay materials[J].Applied Clay Science,2011,54(1):97-106.
[15] 张季如,祝杰,黄丽,等.固结条件下软黏土微观孔隙结构的演化及其分形描述[J].水利学报,2008,39(4):394-400 (ZHANG Jiru,ZHU Jie,HUANG Li,et al.Evolution of micro pore structure of soft clay and its fractal features under consolidation[J].Journal of Hydraulic Engineering,2008,39(4):394-400 (in Chinese))
[16] 周晖.珠江三角洲软土显微结构与渗流固结机理研究[D].华南理工大学,2013 (ZHOU Hui.Study on soft soil microstructure and mechanism of seepage and consolidation in Pearl River Delta[D].South China University of Technology,2013 (in Chinese))
[17] 毛灵涛,薛茹,安里千,等.软土孔隙微观结构的分形研究[J].中国矿业大学学报,2005,34(5):600-604 (MAO Lingtao,XUE Ru,AN Liqian,et al.Fractal approach on soft soil porosity microstructure[J].Journal of China University of Mining & Technology,2005,34(5):600-604 (in Chinese))
[18] 施斌.粘性土微观结构定向性的定量研究[J].地质学报,1997,71(1):36-44 (SHI Bin.Quantitative research on the orientation of microstructures of clayey soil [J].Acta Geologica Sinica,1997,71(1):36-44 (in Chinese))
[19] 胡瑞林.粘性土微结构定量模型及其工程地质特征研究[M].地质出版社,1995 (HU Ruilin.Quantitative microstructure models of clayey soils and their engineering behaviors[M].Geological Publishing House,1995 (in Chinese))