柔性侧限条件下软土的变形特性及固结模型
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摘要
软黏土具有含水率高、压缩性强、泊松比大的物理特性。对于深厚软黏土地基而言,在竖向荷载的作用下很难保证侧向变形为0,适当考虑侧向变形的柔性约束条件可能更符合工程实际。因此,提出了柔性侧限条件下的竖向固结试验方法,对原状土样及重塑土样分别进行了不同侧向约束条件下的竖向固结对比试验,分析了侧限条件对软黏土沉降特征及变形参数的影响。试验成果表明,柔性侧限条件下土体的主固结变形量、次固结变形量均较K_0侧限条件下的大,主固结完成时间较短,且等时曲线非线性化程度更高。基于试验成果及ε-lgp曲线,引入非达西渗流理论,对一维Terzaghi经典固结理论进行修正,建立了柔性侧限约束条件下的非线性控制方程,此计算模型参数通过柔性侧限固结试验获取,可计算一定侧向变形条件下土体的变形特性,通过对室内试验成果的模拟验证了模型的有效性。
Soft clay is characterized by high water content, large compressibility and Poisson's ratio. For thick soft soil foundation, it is difficult to ensure that the lateral deformation remains zero under vertical loading. The condition of flexible constraints with proper consideration of lateral deformation is more realistic with engineering practices. Therefore, in this paper, a consolidation test with flexible lateral constraints was conducted on the undisturbed and remodeled soils. The influences of the lateral constraints on the settlement characteristics and deformation parameters of soft clay were investigated. The results show that both the primary and secondary consolidation deformations of the soil under flexible constraints are greater than those under the K_0 lateral confining conditions, as well as performing a shorter consolidation time and more nonlinear isochronous curves. The theory of non-Darcy flow was introduced to modify the Terzaghi's consolidation theory, so that nonlinear governing equations considering the certain lateral deformation effect were deduced. Furthermore, the parameters of the calculated model were obtained from the flexible lateral restraints consolidation tests. Finally, the validity of the proposed model was verified by the laboratory test results.
Soft clay is characterized by high water content, large compressibility and Poisson's ratio. For thick soft soil foundation, it is difficult to ensure that the lateral deformation remains zero under vertical loading. The condition of flexible constraints with proper consideration of lateral deformation is more realistic with engineering practices. Therefore, in this paper, a consolidation test with flexible lateral constraints was conducted on the undisturbed and remodeled soils. The influences of the lateral constraints on the settlement characteristics and deformation parameters of soft clay were investigated. The results show that both the primary and secondary consolidation deformations of the soil under flexible constraints are greater than those under the K_0 lateral confining conditions, as well as performing a shorter consolidation time and more nonlinear isochronous curves. The theory of non-Darcy flow was introduced to modify the Terzaghi's consolidation theory, so that nonlinear governing equations considering the certain lateral deformation effect were deduced. Furthermore, the parameters of the calculated model were obtained from the flexible lateral restraints consolidation tests. Finally, the validity of the proposed model was verified by the laboratory test results.
引文
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[11]周殷康,阎长虹,邵勇,等.考虑侧向变形的软土地基沉降计算方法研究[J].水文地质工程地质,2015,42(1):95-99.ZHOU Yin-kang,YAN Chang-hong,SHAO Yong,et al.Research on the settlement-calculation in soft soil considering the lateral deformation[J].Hydrogeology&Engineering Geology,2015,42(1):95-99.
[12]卢萌盟,谢康和,李传勋,等.考虑桩土侧向变形的复合地基固结解[J].岩土工程学报,2011,33(2):181-187.LU Meng-meng,XIE Kang-he,LI Chuan-xun,et al.Analytical solution for consolidation of composite ground considering lateral deformations of column and surrounding soil[J].Chinese Journal of Geotechnical Engineering,2011,33(2):181-187.
[13]杨光华,姚丽娜,姜燕,等.基于e-p曲线的软土地基非线性沉降的实用计算方法[J].岩土工程学报,2015,37(2):242-249.YANG Guang-hua,YAO Li-na,JIANG Yan,et al.Pratical method for calculating nonlinear settlement of soft ground based on e-p curve[J].Chinese Journal of Geotechnical Engineering,2015,37(2):242-249.
[14]杨光华.地基沉降计算的新方法[J].岩石力学与工程学报,2008,27(4):679-686.YANG Guang-hua.New computation method for soil foundation settlements[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(4):679-686.
[15]王志亮,高峰,殷宗泽,等.考虑侧向变形的路堤沉降一维法计算修正系数研究[J].岩土力学,2005,26(5):763-768.WANG Zhi-liang,GAO Feng,YIN Zong-ze,et al.Study on modified factors for 1-D calculation of embankment settlement considering soil lateral deformation[J].Rock and Soil Mechanics,2005,26(5):763-768.
[16]张宇,陈善雄,余飞,等.南水北调高填方渠道沉降过程计算方法研究[J].岩石力学与工程学报,2014,33(增刊2):4367-4374.ZHANG Yu,CHEN Shan-xiong,YU Fei,et al.Calculation method study of settlement process of high filling channels in South-to-North Water Diversion Project[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(Suppl.2):4367-4374.
[17]李国维,李响,阮玉胜,等.平面变形超固结软黏土蠕变模型研究[J].岩石力学与工程学报,2016,35(11):2307-2315.LI Guo-wei,LI Xiang,RUAN Yu-sheng,et al.Creep model of over-consolidated soft clay under plane strain[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(11):2307-2315.
[18]李国维,蒋华忠,杨涛,等.路堤下深厚软土侧向变形的沉降影响研究[J].岩土力学,2008,29(10):2817-2822.LI Guo-wei,JIANG Hua-zhong,YANG Tao,et al.Influence of lateral deformation on settlement of thick soft soil underlying embankment[J].Rock and Soil Mechanics,2008,29(10):2817-2822.
[19]BUISMAN A S K.Results of long duration settlement tests[C]//Proceedings of the First International Conference on Soil Mechanics and Foundation Engineering.Cambridge:International Society of Soil Mechanics and Geotechnical Engineering,1936:103-107.
[20]LADD C C.Settlement analysis of cohesive soils[R].Boston:Massachusetts Institute of Technology,1971.
[21]BERRY P L,POSKITT T J.The consolidation of peat[J].Geotechnique,1972,22(1):27-52.
[2]周镜.软土沉降分析中的某些问题[J].中国铁道科学,1999,20(2):17-29.ZHOU Jing.Some problems in analysis of settlement of clay[J].China Railway Science,1999,20(2):17-29.
[3]LOGANATHAN N,BALASUBRAMANIAMA A S,BERGADO D T.Deformation analysis of embankments[J].Journal of Geotechnical Engineering,1993,119(8):1185-1206.
[4]TAVENAS F,MIEUSSENS C,BOURGES F.Lateral displacement in clay foundations under embankment[J].Canadian Geotechnical Journal,1979,16(3):532-550.
[5]MAGNAN J,MIEUSSENS C,QUEYROI D.Etude d’un remblai sur sols compressibles:Le remblai B du site experimental de Cubzac-les-ponts[M].France:Laboratoire Central des Ponts et Chaussees,1983.
[6]中国建筑科学研究院.GB 50007―2011建筑地基基础设计规范[S].北京:中国建筑工业出版社,2011.China Academy of Building Research.GB 50007―2011Code for design of building foundation[S].Beijing:China Architecture&Building Press,2011.
[7]交通部第一公路勘察设计院.JTJ 017―96公路软土地基路堤设计与施工技术规范[S].北京:人民交通出版社,1996.The First Highway Survey and Design Institute of Ministry of Transport.JTJ 017―96 Technical specifications for design and construction of highway embankment on soft ground[S].Beijing:China Communications Press,1996.
[8]中华人民共和国水利部.GB 50286―2013堤防工程设计规范[S].北京:中国计划出版社,2013.Ministry of Water Resources of the People’s Republic of China.GB 50286―2013 Code for design of levee project[S].Beijing:China Planning Press,2013.
[9]中交天津港湾工程研究院有限公司.JTS 147―1―2010港口工程地基规范[S].北京:人民交通出版社,2010.Tianjin Port Engineering Institute Co.,Ltd.of CCCC First Harbor Engineering Ltd.JTS 147―1―2010 Code for soil foundation of port engineering[S].Beijing:China Communications Press,2010.
[10]龚晓南.高等土力学[M].杭州:浙江大学出版社,1996.GONG Xiao-nan.Advanced soil mechanics[M].Hangzhou:Zhejiang University Press,1996.
[11]周殷康,阎长虹,邵勇,等.考虑侧向变形的软土地基沉降计算方法研究[J].水文地质工程地质,2015,42(1):95-99.ZHOU Yin-kang,YAN Chang-hong,SHAO Yong,et al.Research on the settlement-calculation in soft soil considering the lateral deformation[J].Hydrogeology&Engineering Geology,2015,42(1):95-99.
[12]卢萌盟,谢康和,李传勋,等.考虑桩土侧向变形的复合地基固结解[J].岩土工程学报,2011,33(2):181-187.LU Meng-meng,XIE Kang-he,LI Chuan-xun,et al.Analytical solution for consolidation of composite ground considering lateral deformations of column and surrounding soil[J].Chinese Journal of Geotechnical Engineering,2011,33(2):181-187.
[13]杨光华,姚丽娜,姜燕,等.基于e-p曲线的软土地基非线性沉降的实用计算方法[J].岩土工程学报,2015,37(2):242-249.YANG Guang-hua,YAO Li-na,JIANG Yan,et al.Pratical method for calculating nonlinear settlement of soft ground based on e-p curve[J].Chinese Journal of Geotechnical Engineering,2015,37(2):242-249.
[14]杨光华.地基沉降计算的新方法[J].岩石力学与工程学报,2008,27(4):679-686.YANG Guang-hua.New computation method for soil foundation settlements[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(4):679-686.
[15]王志亮,高峰,殷宗泽,等.考虑侧向变形的路堤沉降一维法计算修正系数研究[J].岩土力学,2005,26(5):763-768.WANG Zhi-liang,GAO Feng,YIN Zong-ze,et al.Study on modified factors for 1-D calculation of embankment settlement considering soil lateral deformation[J].Rock and Soil Mechanics,2005,26(5):763-768.
[16]张宇,陈善雄,余飞,等.南水北调高填方渠道沉降过程计算方法研究[J].岩石力学与工程学报,2014,33(增刊2):4367-4374.ZHANG Yu,CHEN Shan-xiong,YU Fei,et al.Calculation method study of settlement process of high filling channels in South-to-North Water Diversion Project[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(Suppl.2):4367-4374.
[17]李国维,李响,阮玉胜,等.平面变形超固结软黏土蠕变模型研究[J].岩石力学与工程学报,2016,35(11):2307-2315.LI Guo-wei,LI Xiang,RUAN Yu-sheng,et al.Creep model of over-consolidated soft clay under plane strain[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(11):2307-2315.
[18]李国维,蒋华忠,杨涛,等.路堤下深厚软土侧向变形的沉降影响研究[J].岩土力学,2008,29(10):2817-2822.LI Guo-wei,JIANG Hua-zhong,YANG Tao,et al.Influence of lateral deformation on settlement of thick soft soil underlying embankment[J].Rock and Soil Mechanics,2008,29(10):2817-2822.
[19]BUISMAN A S K.Results of long duration settlement tests[C]//Proceedings of the First International Conference on Soil Mechanics and Foundation Engineering.Cambridge:International Society of Soil Mechanics and Geotechnical Engineering,1936:103-107.
[20]LADD C C.Settlement analysis of cohesive soils[R].Boston:Massachusetts Institute of Technology,1971.
[21]BERRY P L,POSKITT T J.The consolidation of peat[J].Geotechnique,1972,22(1):27-52.
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