粉煤灰改性分散性土的工程特性试验研究
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摘要
针对分散性土抗冲蚀能力较差,易发生渗透变形的特点,采用粉煤灰作为改性材料,通过针孔试验、碎块试验、压缩试验以及自身抗渗试验研究了粉煤灰对土的分散性、变形和抗渗性能的影响,并采用扫描电镜等试验探讨了微观结构的变化,分析了粉煤灰对土的分散性的改性机制。试验结果表明粉煤灰对土的分散性、压缩性和抗渗特性有明显的改善作用,其中粉煤灰剂量、养护龄期以及压实度对改性效果均有影响。随着粉煤灰剂量和压实度的增加,改性土的分散性和压缩性逐渐降低;随着养护龄期的增加,改性土的压缩性逐渐降低,并在养护前期(7 d以内)变化明显。粉煤灰对分散性土的改性机制在于通过水解和水化、离子交换、硬凝反应等,增强土颗粒间的胶结作用。建议在实际工程中粉煤灰剂量控制在4%~10%之间,养护时间在7 d以上,压实度控制在96%以上。
Dispersive clay is a problematic soil that has too low erosion resistance.To improve its behaviors,we have conducted pinhole tests and crumb tests as well as compression and seepage deformation tests on the dispersive clay modified with different fly ash content.And SEM tests were used to analyze the microstructure and mechanism.The results showed that adding fly ash produced a significant improvement on dispersity,compressibility and permeability of this modified dispersive clay that depended on fly ash content,curing period,and compaction degree.Its dispersity and compressibility were both decreased with an increase in fly ash content or compaction degree; its compressibility was also decreased with an increase in curing period.The mechanism of all the improvement was a series of physical and chemical reactions between fly ash particles and soil particles.Adding fly ash was able to promote the formation of granular structure and reduce soil dispersity through hydration and hydrolysis reaction,ion exchange reaction,and hard condensation reaction.Thus,by mixing fly ash into dispersive clay,it is possible to transform it into non-dispersive clay.For engineering application,this study suggests a fly ash content of 4%-10%,a curing period of longer than 7 days,and a compaction degree of 96%.
Dispersive clay is a problematic soil that has too low erosion resistance.To improve its behaviors,we have conducted pinhole tests and crumb tests as well as compression and seepage deformation tests on the dispersive clay modified with different fly ash content.And SEM tests were used to analyze the microstructure and mechanism.The results showed that adding fly ash produced a significant improvement on dispersity,compressibility and permeability of this modified dispersive clay that depended on fly ash content,curing period,and compaction degree.Its dispersity and compressibility were both decreased with an increase in fly ash content or compaction degree; its compressibility was also decreased with an increase in curing period.The mechanism of all the improvement was a series of physical and chemical reactions between fly ash particles and soil particles.Adding fly ash was able to promote the formation of granular structure and reduce soil dispersity through hydration and hydrolysis reaction,ion exchange reaction,and hard condensation reaction.Thus,by mixing fly ash into dispersive clay,it is possible to transform it into non-dispersive clay.For engineering application,this study suggests a fly ash content of 4%-10%,a curing period of longer than 7 days,and a compaction degree of 96%.
引文
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[3]樊恒辉,孔令伟,李洪良,等.马家树水库大坝防渗土料分散性判别和改性试验[J].岩土力学,2010,31(1):193-198.FAN Henghui,KONG Lingwei,LI Hongliang,et al.Study of dispersive identification and treatment with lime of dam soil in Majiashu reservoir[J].Rock and Soil Mechanics,2010,31(1):193-198.(in Chinese)
[4]王中妮,樊恒辉,贺智强,等.分散性土改性剂对土的分散性和抗拉强度的影响[J].岩石力学与工程学报,2015,34(2):425-432.WANG Zhongni,FAN Henghui,HE Zhiqiang,et al.Influence of modifiers on dispersity and tensile strength of dispersive clay[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(2):425-432.(in Chinese)
[5]冯海宁,杨有海,龚晓南.粉煤灰工程特性的试验研究[J].岩土力学,2002,23(5):579-582.FENG Haining,YANG Youhai,GONG Xiaonan.Test research on engineering characteristic of fly ash[J].Rock and Soil Mechanics,2002,23(5):579-582.(in Chinese)
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[7]魏海斌,刘寒冰,高一平,等.循环荷载下粉质中液限黏土和粉煤灰土的动剪强度研究[J].岩土力学,2007,28(9):1927-1930.WEI Haibin,LIU Hanbing,GAO Yiping,et al.Study on dynamic shear strength of middle-liquidity limit silty clay and fly ash soils under cyclic loading[J].Rock and Soil Mechanics,2007,28(9):1927-1930.(in Chinese)
[8]温彦锋,边京红,蔡红.凝硬和冻融作用对干贮粉煤灰的力学性质的影响[J].岩土工程学报,2000,22(3):275-278.WEN Yanfeng,BIAN Jinghong,CAI Hong.The effect of pozzolanic action and frost and thaw cycles on the mechanical characteristics of dry-disposed fly ash[J].Chinese Journal of Geotechnical Engineering,2000,22(3):275-278.(in Chinese)
[9]Ravi K S,Babita S.Modification of clayer soil using fly ash[J].International Journal of Research in Engineering and Technology,2013,2(10):356-361.
[10]Horpibulsuk S,Rachan R,Chinkulkijniwat A,et al.Analysis of strength development in cement-stabilized silty clay from microstructural considerations[J].Construction and Building Materials,2010,24(10):2011-2021.
[11]Horpibulsuk S,Phetchuay C,Chinkulkijniwat A.Soil stabilization by calcium carbide residue and fly ash[J].Journal of Materials in Civil Engineering,2012,24(2):184-193.
[12]王东星,徐卫亚.大掺量粉煤灰淤泥固化土的强度与耐久性研究[J].岩土力学,2012,33(12):3659-3664.WANG Dongxing,XU Weiya.Research on strength and durability of sediments solidified with high volume fly ash[J].Rock and Soil Mechanics,2012,33(12):3659-3664.(in Chinese)
[13]吕擎峰,李晓媛,赵彦旭,等.改性黄土的冻融特性[J].中南大学学报(自然科学版),2014,45(3):819-825.LüQingfeng,LI Xiaoyuan,ZHAO Yanxu,et al.Properties of modified loess under freeze-thaw cycles[J].Journal of Central South University(Science and Technologh),2014,45(3):819-825.(in Chinese)
[14]祝艳波,余宏明,杨艳霞,等.红层泥岩改良土特性室内试验研究[J].岩石力学与工程学报,2013,32(2):425-432.ZHU Yanbo,YU Hongming,YANG Yanxia,et al.Indoor experimental research on characteristics of imperoved red-mudstone[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(2):425-432.(in Chinese)
[15]The American Society for Testing and Material.Standard test method for identification and classification of dispersive clay soils by the pinhole test:D 4647—93[S].West Conshohocken:ASTM,1993.
[16]The American Society for Testing and Material.Standard test methods for determining dispersive characteristics of clayey soils by the crumb test:D 6572—00[S].West Conshohocken:ASTM,2000.
[17]Fan H H,Kong L W.Empirical equation for evaluating the dispersivity of cohesive soil[J].Canadian Geotechnical Journal,2013,50(9):989-994.
[18]樊恒辉,孔令伟,郭敏霞,等.文家沟水库筑坝土料分散性和抗渗性能试验[J].岩土工程学报,2009,31(3):458-463.FAN Henghui,KONG Linwei,GUO Minxia,et al.Dispersivity and impermeability of dam soil in Wenjiagou Reservoir[J].Chinese Journal of Geotechnical Engineering,2009,31(3):458-463.(in Chinese)
[19]党进谦,马晓婷,孙仲林,等.分散性对心墙土料裂缝冲刷影响的试验研究[J].水利学报,2012,43(9):1103-1107.DANG Jinqian,MA Xiaoting,SUN Zhonglin,et al.Experimental study on influence of dispersion on the crack washout of the core wall material[J].Journal of Hydraulic Engineering,2012,43(9):1103-1107.(in Chinese)
[20]樊恒辉,李洪良,赵高文.黏性土的物理化学及矿物学性质与分散机理[J].岩土工程学报,2012,34(9):1740-1745.FAN Henghui,LI Hongliang,ZHAO Gaowen.Relation among dispersive mechanism physical-chemical and mineral properties of clayey soil[J].Chinese Journal of Geotechnical Engineering,2012,34(9):1740-1745.(in Chinese)
[2]刘杰.土石坝渗流控制理论基础及工程经验教训[M].北京:中国水利水电出版社,2006.LIU Jie.Seepage control of earch-rock dams theoretical basis,engineering experidnces and lessons[M].Beijing:China Water Power Press,2006.(in Chinese)
[3]樊恒辉,孔令伟,李洪良,等.马家树水库大坝防渗土料分散性判别和改性试验[J].岩土力学,2010,31(1):193-198.FAN Henghui,KONG Lingwei,LI Hongliang,et al.Study of dispersive identification and treatment with lime of dam soil in Majiashu reservoir[J].Rock and Soil Mechanics,2010,31(1):193-198.(in Chinese)
[4]王中妮,樊恒辉,贺智强,等.分散性土改性剂对土的分散性和抗拉强度的影响[J].岩石力学与工程学报,2015,34(2):425-432.WANG Zhongni,FAN Henghui,HE Zhiqiang,et al.Influence of modifiers on dispersity and tensile strength of dispersive clay[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(2):425-432.(in Chinese)
[5]冯海宁,杨有海,龚晓南.粉煤灰工程特性的试验研究[J].岩土力学,2002,23(5):579-582.FENG Haining,YANG Youhai,GONG Xiaonan.Test research on engineering characteristic of fly ash[J].Rock and Soil Mechanics,2002,23(5):579-582.(in Chinese)
[6]冯美果,陈善雄,余颂,等.粉煤灰改性膨胀土水稳定性试验研究[J].岩土力学,2007,28(9):1889-1893.FENG Meiguo,CHEN Shanxiong,YU Song,et al.Laboratory study on water stability of fly ash-modified expansive soil[J].Rock and Soil Mechanics,2007,28(9):1889-1893.(in Chinese)
[7]魏海斌,刘寒冰,高一平,等.循环荷载下粉质中液限黏土和粉煤灰土的动剪强度研究[J].岩土力学,2007,28(9):1927-1930.WEI Haibin,LIU Hanbing,GAO Yiping,et al.Study on dynamic shear strength of middle-liquidity limit silty clay and fly ash soils under cyclic loading[J].Rock and Soil Mechanics,2007,28(9):1927-1930.(in Chinese)
[8]温彦锋,边京红,蔡红.凝硬和冻融作用对干贮粉煤灰的力学性质的影响[J].岩土工程学报,2000,22(3):275-278.WEN Yanfeng,BIAN Jinghong,CAI Hong.The effect of pozzolanic action and frost and thaw cycles on the mechanical characteristics of dry-disposed fly ash[J].Chinese Journal of Geotechnical Engineering,2000,22(3):275-278.(in Chinese)
[9]Ravi K S,Babita S.Modification of clayer soil using fly ash[J].International Journal of Research in Engineering and Technology,2013,2(10):356-361.
[10]Horpibulsuk S,Rachan R,Chinkulkijniwat A,et al.Analysis of strength development in cement-stabilized silty clay from microstructural considerations[J].Construction and Building Materials,2010,24(10):2011-2021.
[11]Horpibulsuk S,Phetchuay C,Chinkulkijniwat A.Soil stabilization by calcium carbide residue and fly ash[J].Journal of Materials in Civil Engineering,2012,24(2):184-193.
[12]王东星,徐卫亚.大掺量粉煤灰淤泥固化土的强度与耐久性研究[J].岩土力学,2012,33(12):3659-3664.WANG Dongxing,XU Weiya.Research on strength and durability of sediments solidified with high volume fly ash[J].Rock and Soil Mechanics,2012,33(12):3659-3664.(in Chinese)
[13]吕擎峰,李晓媛,赵彦旭,等.改性黄土的冻融特性[J].中南大学学报(自然科学版),2014,45(3):819-825.LüQingfeng,LI Xiaoyuan,ZHAO Yanxu,et al.Properties of modified loess under freeze-thaw cycles[J].Journal of Central South University(Science and Technologh),2014,45(3):819-825.(in Chinese)
[14]祝艳波,余宏明,杨艳霞,等.红层泥岩改良土特性室内试验研究[J].岩石力学与工程学报,2013,32(2):425-432.ZHU Yanbo,YU Hongming,YANG Yanxia,et al.Indoor experimental research on characteristics of imperoved red-mudstone[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(2):425-432.(in Chinese)
[15]The American Society for Testing and Material.Standard test method for identification and classification of dispersive clay soils by the pinhole test:D 4647—93[S].West Conshohocken:ASTM,1993.
[16]The American Society for Testing and Material.Standard test methods for determining dispersive characteristics of clayey soils by the crumb test:D 6572—00[S].West Conshohocken:ASTM,2000.
[17]Fan H H,Kong L W.Empirical equation for evaluating the dispersivity of cohesive soil[J].Canadian Geotechnical Journal,2013,50(9):989-994.
[18]樊恒辉,孔令伟,郭敏霞,等.文家沟水库筑坝土料分散性和抗渗性能试验[J].岩土工程学报,2009,31(3):458-463.FAN Henghui,KONG Linwei,GUO Minxia,et al.Dispersivity and impermeability of dam soil in Wenjiagou Reservoir[J].Chinese Journal of Geotechnical Engineering,2009,31(3):458-463.(in Chinese)
[19]党进谦,马晓婷,孙仲林,等.分散性对心墙土料裂缝冲刷影响的试验研究[J].水利学报,2012,43(9):1103-1107.DANG Jinqian,MA Xiaoting,SUN Zhonglin,et al.Experimental study on influence of dispersion on the crack washout of the core wall material[J].Journal of Hydraulic Engineering,2012,43(9):1103-1107.(in Chinese)
[20]樊恒辉,李洪良,赵高文.黏性土的物理化学及矿物学性质与分散机理[J].岩土工程学报,2012,34(9):1740-1745.FAN Henghui,LI Hongliang,ZHAO Gaowen.Relation among dispersive mechanism physical-chemical and mineral properties of clayey soil[J].Chinese Journal of Geotechnical Engineering,2012,34(9):1740-1745.(in Chinese)
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