污染粉质粘土液塑限试验研究
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摘要
随着我国经济的飞速发展,人口的不断增长,由人类活动造成的环境污染和生态破坏对环境产生的负面影响变得越来越突出。特别是在工程建设中,地基土被典型污染源影响后,土中不同矿物成分被腐蚀,土体结构发生改变、地基强度降低,甚至造成构造物的失稳或破坏,所以地基土污染后的工程性质的变化是环境岩土工程研究的重点问题之一。
本项目结合山西地区的污染特色,选取太原某场地的粉质粘土为研究对象,采用室内模拟试验的方法,用粉质粘土在不同浓度的生活污水和造纸厂污水污染下形成污染土,通过测定污染前后土的液限、塑限和塑性指数等物理指标,对比分析污染对土的稠度指标的影响规律,为研究污染土的治理和修复措施提供基础数据。
首先,现场采取典型污染液(生活污水和造纸厂污水),配置不同浓度的溶液,与干土混合制备污染土样。从表观上可以看出污染前后土样表面状态不同,污染后表面呈黑色或灰色且有晶体出现象。分析原因可能是由于土体颗粒与污染物发生反应或土体中的游离氧化物和水溶盐含量与溶液作用发生化学溶蚀、沉淀等反应,生成新的物质。
其次,对两种不同污染源的土样进行液塑限测定,得出:(1)土的可塑性变化与污染源的成分和浓度紧密相关;(2)污染土样随侵蚀龄期的增加,可塑性变化显著;(3)土样在造纸厂碱性污水的侵蚀下,液、塑限均大于无污染状态,且液、塑限和塑性指数随污染溶液浓度的增加而增大;(4)生活污水污染的土样,其液限均小于无污染状态,且随着溶液浓度的增加而减小;塑限正好相反;塑性指数均小于无污染状态,且随着溶液浓度的增加而减小。
土样的可塑性的变化与土粒表面结合水膜的厚度即扩散层的厚度变化有关,而土体结合水膜的厚度在很大程度上决定于与土体相互作用的污染溶液的化学成分和浓度。在不同浓度的造纸厂污水和生活污水污染下,溶液中的某些离子与土样中的矿物发生置换反应,导致粘粒电动电位发生变化,同时孔隙水中离子类型和浓度变化,使土颗粒表面结合水膜变厚或变薄,导致土体的稠度指标发生改变。这些变化进而可能导致土体的力学性质改变。
With rapid economic development and increasing population in our country, negative effects on environment caused by environmental pollution and ecological damage during the process of human activities have become a problem that is more serious than ever before. In engineering construction, if the subsoil is polluted by some kind of typical pollution source, the different sorts of minerals in the soil could be eroded, and the soil microstructure may be changing, then consequently the bearing capacity may be reduced, and even buildings on it could be destabilized or destroyed. Thus engineering properties study of contaminated subsoil is one of important issues in environmental and geotechnical engineering.
Considering the characteristics of pollution in Shanxi province, the silty clay from a building site in Taiyuan is chosen as the research object. Simulation test in door is applied. In the experimental process, the contaminated soil is obtained by mixing silty clay with the domestic sewage or sewage of paper mill which are of different concentrations. The physical indexes of the soil before and after contaminating, including liquid limit, plastic limit, index of plasticity, are measured. The test results on how contamination resource is to affect the consistency of soil are valuable for understanding the contaminated soil and providing suitable improvement method.
In this paper, the sample of typical contaminating fluid (such as domestic sewage and sewage from paper mill) were collected in site; solutions of different concentrations were prepare for above two types of fluid, then dry soil was mixed with the solution to make contaminated soil. Appearances of contaminated soil samples are different from those uncontaminated. Contaminated soils have black or gray crystals on their appearance, which might be because new mineral composition is produced when soil grains interact with contaminants or free oxide in soil mass and deliquescent salt denudate or precipitate.
Secondly, by measuring liquid limit and plastic limit of contaminated soils by two different contamination sources, the conclusions are dawn out: (1) Plasticity changes of the soil are closely related to the component and concentration of the contaminants. (2) Plasticity changing of the soil are increasingly significant with the erosion period. (3) When soil is eroded by alkaline sewage from paper mill, its liquid and plastic limits are greater than those are not eroded. The higher concentration of contaminating solution is the greater liquid limit, plastic limit and plastic index are. (4) When soil is eroded by domestic sewage, its liquid limit and plastic index are greater than those are not eroded. The higher concentration of contaminating solution is the lower liquid limit and plastic index. But its plastic limit is greater than that is not eroded.
Plasticity of soil samples is related to thickness of combined water file of soil grain, which is determined by components and concentration of contaminating solution interacting with soil mass. After the soil polluted by sewage from paper mill or domestic sewage, the some ions may be replaced by the ions in the solution. Thus electro kinetic potential of clay grain changes, at mean time, the types and concentrations of ions in void water are changed too, both of which determine the thickness of the combined water film of soil grain, then induces changes of soil consistency. All these changes may in turn cause the changes of mechanical property of the soil mass.
本项目结合山西地区的污染特色,选取太原某场地的粉质粘土为研究对象,采用室内模拟试验的方法,用粉质粘土在不同浓度的生活污水和造纸厂污水污染下形成污染土,通过测定污染前后土的液限、塑限和塑性指数等物理指标,对比分析污染对土的稠度指标的影响规律,为研究污染土的治理和修复措施提供基础数据。
首先,现场采取典型污染液(生活污水和造纸厂污水),配置不同浓度的溶液,与干土混合制备污染土样。从表观上可以看出污染前后土样表面状态不同,污染后表面呈黑色或灰色且有晶体出现象。分析原因可能是由于土体颗粒与污染物发生反应或土体中的游离氧化物和水溶盐含量与溶液作用发生化学溶蚀、沉淀等反应,生成新的物质。
其次,对两种不同污染源的土样进行液塑限测定,得出:(1)土的可塑性变化与污染源的成分和浓度紧密相关;(2)污染土样随侵蚀龄期的增加,可塑性变化显著;(3)土样在造纸厂碱性污水的侵蚀下,液、塑限均大于无污染状态,且液、塑限和塑性指数随污染溶液浓度的增加而增大;(4)生活污水污染的土样,其液限均小于无污染状态,且随着溶液浓度的增加而减小;塑限正好相反;塑性指数均小于无污染状态,且随着溶液浓度的增加而减小。
土样的可塑性的变化与土粒表面结合水膜的厚度即扩散层的厚度变化有关,而土体结合水膜的厚度在很大程度上决定于与土体相互作用的污染溶液的化学成分和浓度。在不同浓度的造纸厂污水和生活污水污染下,溶液中的某些离子与土样中的矿物发生置换反应,导致粘粒电动电位发生变化,同时孔隙水中离子类型和浓度变化,使土颗粒表面结合水膜变厚或变薄,导致土体的稠度指标发生改变。这些变化进而可能导致土体的力学性质改变。
With rapid economic development and increasing population in our country, negative effects on environment caused by environmental pollution and ecological damage during the process of human activities have become a problem that is more serious than ever before. In engineering construction, if the subsoil is polluted by some kind of typical pollution source, the different sorts of minerals in the soil could be eroded, and the soil microstructure may be changing, then consequently the bearing capacity may be reduced, and even buildings on it could be destabilized or destroyed. Thus engineering properties study of contaminated subsoil is one of important issues in environmental and geotechnical engineering.
Considering the characteristics of pollution in Shanxi province, the silty clay from a building site in Taiyuan is chosen as the research object. Simulation test in door is applied. In the experimental process, the contaminated soil is obtained by mixing silty clay with the domestic sewage or sewage of paper mill which are of different concentrations. The physical indexes of the soil before and after contaminating, including liquid limit, plastic limit, index of plasticity, are measured. The test results on how contamination resource is to affect the consistency of soil are valuable for understanding the contaminated soil and providing suitable improvement method.
In this paper, the sample of typical contaminating fluid (such as domestic sewage and sewage from paper mill) were collected in site; solutions of different concentrations were prepare for above two types of fluid, then dry soil was mixed with the solution to make contaminated soil. Appearances of contaminated soil samples are different from those uncontaminated. Contaminated soils have black or gray crystals on their appearance, which might be because new mineral composition is produced when soil grains interact with contaminants or free oxide in soil mass and deliquescent salt denudate or precipitate.
Secondly, by measuring liquid limit and plastic limit of contaminated soils by two different contamination sources, the conclusions are dawn out: (1) Plasticity changes of the soil are closely related to the component and concentration of the contaminants. (2) Plasticity changing of the soil are increasingly significant with the erosion period. (3) When soil is eroded by alkaline sewage from paper mill, its liquid and plastic limits are greater than those are not eroded. The higher concentration of contaminating solution is the greater liquid limit, plastic limit and plastic index are. (4) When soil is eroded by domestic sewage, its liquid limit and plastic index are greater than those are not eroded. The higher concentration of contaminating solution is the lower liquid limit and plastic index. But its plastic limit is greater than that is not eroded.
Plasticity of soil samples is related to thickness of combined water file of soil grain, which is determined by components and concentration of contaminating solution interacting with soil mass. After the soil polluted by sewage from paper mill or domestic sewage, the some ions may be replaced by the ions in the solution. Thus electro kinetic potential of clay grain changes, at mean time, the types and concentrations of ions in void water are changed too, both of which determine the thickness of the combined water film of soil grain, then induces changes of soil consistency. All these changes may in turn cause the changes of mechanical property of the soil mass.
引文
[1]钟真宜,罗建中,陈敏.推进产业生态化实现可持续发展[J].中国环保产.2008, (5):28.
[2]王晓荣.污染环境对水泥土强度的影响研究[D].太原:太原理工大学,2008.
[3]王思敬,周平根.环境地质学的现状与发展方向展望[J].工程地质学报.1995,3(4):12-180.
[4]陈云敏,施建勇.中国环境岩土工程的进展[M].重庆:重庆大学出版社,上册,2007:114-129.
[5]孙秀丽,孔宪京.垃圾士应力—应变关系的室内试验研究[M].重庆:重庆大学出版社,下册,2007:709-713.
[6]陈仁鹏,张延红.TDR技术在检测土体污染中的应用[M].重庆:重庆大学出版社,下册,2007:725-729.
[7]王志萍,胡敏云.城市固体废弃物压缩特性的室内试验[M].重庆:重庆大学出版社,下册,2007:745-750.
[8]霍润科,姚志飞等.化学环境对岩石性质影响的研究与思考[M].重庆:重庆大学出版社,下册,2007:759-763.
[9]李国成,杨武超,但堂辉等.垃圾填埋场及垫层孔隙水压力变化对其稳定性的影响[M].重庆:重庆大学出版社,下册,2007,782-785.
[10]韩鹏举,白晓红,赵永强.硫酸对水泥土早期腐蚀的试验研究[M].重庆:重庆大学出版社,下册,2007:786-789.
[11]方晓阳.21世纪环境岩土工程的展望[J].岩土工程学报,2000,22(1):1-11.
[12] Mitchell J.K. Geotechnology-the Environmental Perspective, Proceedings of the 3rd International Symposium Volume one[C].Pennsylvania: Techno mic Publishing Company, Inc, 1996:1-17.
[13]胡中雄,李向约,方晓阳.环境岩土工程学概论[J].岩土工程学报,1990,12(1): 98-107.
[14]袁建新.环境岩土工程问题综述[J].岩土力学,1990,17(2): 88-93.
[15]龚晓南.21世纪岩土工程发展展望[J].岩土工程学报,2000,22(2):235-24.
[16]罗国煜,陈新民.李晓昭等.城市环境岩土工程[M].南京:南京大学出版社,1996:88- 93.
[17]施斌.环境岩土工程国际会议综述[J].国际学术动态,2005,5:58-60.
[18] Kooper W F, G A Man gnus. Contaminated Soil[M].Martinus Nijhoff Publishers,1986:25-27.
[19]傅世法,林颂恩.污染土的岩土工程问题[J].工程勘察,1989, (3): 14-16.
[20]李明清.关于污染土[J].工程勘察,1986,(5):25-26.
[21]中国科学院南京土壤研究所主编,中国土壤[M].南京:科学出版社,1981:46.
[22] Sridharan A, Nagaraj T S,Sivapullaiah P V . Heaving of soil due to acid contamination[J].Geotechnique , 1980,(2): 258-267.
[23] Ho Y A, Pufahl D E, Barbour S L. Effects of brine contamination on volume change behavior offine-grained soils, Materials from Theory to Practice [A]. Proceedings of the 42nd Canadian Geotechnical conference[C].Winnipeg: Manitoba,1989: 272-279.
[24] Rajput V S, Higgins A J, Single M E. Cleaning of excavated soil contaminated with hazardous organic compounds by washing [A]. Water Environ Res. Sept-Qct 1994 Water Environment Federation [C] .Alexandria ,V A,USA[C].1994:819-827.
[25] Piccoll, Stefano, Benoit. Geo-environmental testing using the Envirocone [A]. Geotech Spec Publ.n46/1 1995 Proceeding of the Specialty Conference on Geotechnical Practice in Waste disposal .Part 1(of2),New Orleans, LA,USA[C].1995:93-104.
[26]饶为国.污染土的机理、检测及整治[J].建筑技术开发,1999,26(1):20-21.
[27]李琦,施斌,王有诚.造纸厂废碱液污染土的环境岩土工程研究[J].环境污染与防治,1999,19(5):16-18.
[28] GB50021-2001,岩土工程勘察规范[S].北京:中国建筑工业出版社,2001.
[29]陈先华,唐辉明.污染土的研究现状及展望[J].地质与勘测,2003,39(1):77-79.
[30]李湘然,姚志祥.城市岩土地基工程地质[M].北京:中国建材工业出版社,2003:106-107.
[31]顾季威.废碱液污染侵蚀对土的强度的影响[J].岩土工程学报,1988,10(4):38.
[32]范青娟,马光锁.浸碱膨胀对地基土的影响与处理[J].轻金属,1999(9):58-62.
[33]路世豹,张建新,雷扬等.某硫酸库地基污染机理的探讨[J].岩土工程界,2002,6(5):37-38.
[34]赵以忠.某厂强酸性废水对红粘土地基侵蚀性的模拟实验[J].勘察科学技术, 1988(2):35-37.
[35]赵树德.土力学[M].北京:高等教育出版社,2004:11-12.
[36]周启星.土壤环境污染化学与化学修复研究最新进展[J].环境化学,2006(3):8-9.
[37]李湘然,姚志祥,曹振斌.济南典型地区地基土污染腐蚀性质变异研究[J].岩土力学, 2004, 25(8): 1229-1233.
[38] JTG E40-2007,土工试验规程[S].北京:人民交通出版社,2007.
[39] GB/T50123-1999,土工试验方法标准[S].北京:中国计划出版社,1999.
[40]胡中雄.土力学与环境土工学[M].上海:同济大学出版社, 1997.
[41]彭意.提高液塑限联合测定试验精度的方法[J].土工基础,2007,21(4):81-82.
[42]徐奋强.粘性土液塑限测定试验研究[J].岩土工程界,2008,9(11):41-42.
[43] Mulhare ,MichaclJ,Therrien .Comparison of field and laboratory methods for the characterization of contaminated soil[A].Geotech Spec Publ.n46/1 1995 Proceeding of the Specialty Conference on Geotechnical Practice in Waste disposal.Part1(of2),New Orleans ,LA ,USA[C].1995,16-17.
[2]王晓荣.污染环境对水泥土强度的影响研究[D].太原:太原理工大学,2008.
[3]王思敬,周平根.环境地质学的现状与发展方向展望[J].工程地质学报.1995,3(4):12-180.
[4]陈云敏,施建勇.中国环境岩土工程的进展[M].重庆:重庆大学出版社,上册,2007:114-129.
[5]孙秀丽,孔宪京.垃圾士应力—应变关系的室内试验研究[M].重庆:重庆大学出版社,下册,2007:709-713.
[6]陈仁鹏,张延红.TDR技术在检测土体污染中的应用[M].重庆:重庆大学出版社,下册,2007:725-729.
[7]王志萍,胡敏云.城市固体废弃物压缩特性的室内试验[M].重庆:重庆大学出版社,下册,2007:745-750.
[8]霍润科,姚志飞等.化学环境对岩石性质影响的研究与思考[M].重庆:重庆大学出版社,下册,2007:759-763.
[9]李国成,杨武超,但堂辉等.垃圾填埋场及垫层孔隙水压力变化对其稳定性的影响[M].重庆:重庆大学出版社,下册,2007,782-785.
[10]韩鹏举,白晓红,赵永强.硫酸对水泥土早期腐蚀的试验研究[M].重庆:重庆大学出版社,下册,2007:786-789.
[11]方晓阳.21世纪环境岩土工程的展望[J].岩土工程学报,2000,22(1):1-11.
[12] Mitchell J.K. Geotechnology-the Environmental Perspective, Proceedings of the 3rd International Symposium Volume one[C].Pennsylvania: Techno mic Publishing Company, Inc, 1996:1-17.
[13]胡中雄,李向约,方晓阳.环境岩土工程学概论[J].岩土工程学报,1990,12(1): 98-107.
[14]袁建新.环境岩土工程问题综述[J].岩土力学,1990,17(2): 88-93.
[15]龚晓南.21世纪岩土工程发展展望[J].岩土工程学报,2000,22(2):235-24.
[16]罗国煜,陈新民.李晓昭等.城市环境岩土工程[M].南京:南京大学出版社,1996:88- 93.
[17]施斌.环境岩土工程国际会议综述[J].国际学术动态,2005,5:58-60.
[18] Kooper W F, G A Man gnus. Contaminated Soil[M].Martinus Nijhoff Publishers,1986:25-27.
[19]傅世法,林颂恩.污染土的岩土工程问题[J].工程勘察,1989, (3): 14-16.
[20]李明清.关于污染土[J].工程勘察,1986,(5):25-26.
[21]中国科学院南京土壤研究所主编,中国土壤[M].南京:科学出版社,1981:46.
[22] Sridharan A, Nagaraj T S,Sivapullaiah P V . Heaving of soil due to acid contamination[J].Geotechnique , 1980,(2): 258-267.
[23] Ho Y A, Pufahl D E, Barbour S L. Effects of brine contamination on volume change behavior offine-grained soils, Materials from Theory to Practice [A]. Proceedings of the 42nd Canadian Geotechnical conference[C].Winnipeg: Manitoba,1989: 272-279.
[24] Rajput V S, Higgins A J, Single M E. Cleaning of excavated soil contaminated with hazardous organic compounds by washing [A]. Water Environ Res. Sept-Qct 1994 Water Environment Federation [C] .Alexandria ,V A,USA[C].1994:819-827.
[25] Piccoll, Stefano, Benoit. Geo-environmental testing using the Envirocone [A]. Geotech Spec Publ.n46/1 1995 Proceeding of the Specialty Conference on Geotechnical Practice in Waste disposal .Part 1(of2),New Orleans, LA,USA[C].1995:93-104.
[26]饶为国.污染土的机理、检测及整治[J].建筑技术开发,1999,26(1):20-21.
[27]李琦,施斌,王有诚.造纸厂废碱液污染土的环境岩土工程研究[J].环境污染与防治,1999,19(5):16-18.
[28] GB50021-2001,岩土工程勘察规范[S].北京:中国建筑工业出版社,2001.
[29]陈先华,唐辉明.污染土的研究现状及展望[J].地质与勘测,2003,39(1):77-79.
[30]李湘然,姚志祥.城市岩土地基工程地质[M].北京:中国建材工业出版社,2003:106-107.
[31]顾季威.废碱液污染侵蚀对土的强度的影响[J].岩土工程学报,1988,10(4):38.
[32]范青娟,马光锁.浸碱膨胀对地基土的影响与处理[J].轻金属,1999(9):58-62.
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[34]赵以忠.某厂强酸性废水对红粘土地基侵蚀性的模拟实验[J].勘察科学技术, 1988(2):35-37.
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