有明黏土各向异性固结特性的试验研究
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摘要
由于大多数黏土矿物是片状的,在沉积和随后的固结过程中黏土颗粒和组构单元趋向水平定向排列,使天然沉积黏土呈现各向异性的固结特性。通过垂直切和水平切试样的恒应变速率固结试验研究了日本有明黏土的各向异性固结特性。试验结果表明,水平切试样的先期固结压力p_(ch)与垂直切试样的先期固结压力p_(cv)的比值在0.5～1.0之间,主要是因为天然沉积黏土各向异性的屈服轨迹以及垂直切和水平切试样所经历的应力路径不同;在正常固结阶段,水平切试样的固结系数c_h与垂直切试样的固结系数c_v之比约为1.43,水平切试样的渗透系数k_h与垂直切试样的渗透系数k_v之比约为1.40,水平切试样的体积压缩系数m_h与垂直切试样的体积压缩系数m_v基本相等。因此,有明黏土固结系数的各向异性主要是因为渗透系数的各向异性,而渗透系数的各向异性本质上是因为其微观结构的各向异性。
Natural sedimentary clays exhibit anisotropic consolidation properties since most clay minerals are platy and the clay particles and fabric elements tend to be horizontally oriented in the deposition and subsequent consolidation processes. In this paper,the anisotropic consolidation properties of Ariake clay in Japan were studied by the constant rate of strain(CRS) consolidation test using vertically and horizontally cut specimens. The test results show that the ratios of the preconsolidation pressure of horizontally cut specimen(p_(ch)) to that of vertically cut specimen(p_(cv)) are in the range from 0.5 to 1.0, which is mainly due to the anisotropic yield locus of natural sedimentary clay and the different stress paths experienced by the vertically and horizontally cut specimens. In the normal consolidation range, the ratio of coefficient of consolidation obtained from horizontally cut specimen(c_h) to that from vertically cut specimen(c_v) is approximately 1.43, and the ratio of hydraulic conductivity obtained from horizontally cut specimen(k_h)to that from vertically cut specimen(k_v) is approximately 1.40, while the coefficient of volume compressibility obtained from horizontally cut specimen(m_h) is approximately equal to that from vertically cut specimen(m_v). Therefore, the anisotropy of coefficient of consolidation of Ariake clay mainly arises from the anisotropy of hydraulic conductivity, which is essentially induced by the anisotropy of microstructure.
Natural sedimentary clays exhibit anisotropic consolidation properties since most clay minerals are platy and the clay particles and fabric elements tend to be horizontally oriented in the deposition and subsequent consolidation processes. In this paper,the anisotropic consolidation properties of Ariake clay in Japan were studied by the constant rate of strain(CRS) consolidation test using vertically and horizontally cut specimens. The test results show that the ratios of the preconsolidation pressure of horizontally cut specimen(p_(ch)) to that of vertically cut specimen(p_(cv)) are in the range from 0.5 to 1.0, which is mainly due to the anisotropic yield locus of natural sedimentary clay and the different stress paths experienced by the vertically and horizontally cut specimens. In the normal consolidation range, the ratio of coefficient of consolidation obtained from horizontally cut specimen(c_h) to that from vertically cut specimen(c_v) is approximately 1.43, and the ratio of hydraulic conductivity obtained from horizontally cut specimen(k_h)to that from vertically cut specimen(k_v) is approximately 1.40, while the coefficient of volume compressibility obtained from horizontally cut specimen(m_h) is approximately equal to that from vertically cut specimen(m_v). Therefore, the anisotropy of coefficient of consolidation of Ariake clay mainly arises from the anisotropy of hydraulic conductivity, which is essentially induced by the anisotropy of microstructure.
引文
[1]李广信.高等土力学[M].北京:清华大学出版社,2016.LI Guang-xin.Advanced soil mechanics[M].Beijing:Tsinghua University Press,2016.
[2]MITCHELL J K,SOGA K.Fundamentals of soil behavior[M].New York:Wiley,2005.
[3]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.
[4]钱家欢,殷宗泽.土工原理与计算[M].2版.北京:中国水利水电出版社,1996.QIAN Jia-huan,YIN Zong-zhe.The principle of soil engineering and calculation[M].2nd ed.Beijing:China Water&Power Press,1996.
[5]袁聚云.软土各向异性性状的试验研究及其在工程中的应用[D].上海:同济大学,1995.YUAN Ju-yun.Test study on soft soil’s anisotropy and its application to practice[D].Shanghai:Tongji University,1995.
[6]CALLISTO L,CALABRESI G.Mechanical behaviour of a natural soft clay[J].Geotechnique,1998,48(4):495-513.
[7]沈扬.考虑主应力方向变化的原状软黏土试验研究[D].杭州:浙江大学,2007.SHEN Yang.Experimental study on effect of variation of principal stress orientation on undisturbed soft clay[D].Hangzhou:Zhejiang University,2007.
[8]GASPARRE A,NISHIMURA S,MINH N A,et al.The stiffness of natural London clay[J].Geotechnique,2007,57(1):33-47.
[9]NISHIMURA S,MINH N A,JARDINE R J.Shear strength anisotropy of natural London clay[J].Geotechnique,2007,57(1):49-62.
[10]艾智勇,董洲,成怡冲,等.三维渗透各向异性层状地基Biot固结分析[J].土木工程学报,2011,44(12):79-84.AI Zhi-yong,DONG Zhou,CHENG Yi-chong,et al.Analysis of three-dimensional Biot’s consolidation of layered soils with anisotropic permeability[J].China Civil Engineering Journal,2011,44(12):79-84.
[11]O’KELLY B C.Compression and consolidation anisotropy of some soft soils[J].Geotechnical and Geological Engineering,2006,24:1715-1728.
[12]WONG L S.Laboratory evaluation of horizontal coefficient of consolidation ch of fibrous peat soil[D].Malaysia:University of Malaya,2005.
[13]宋云奇,武朝军,叶冠林.上海浅部黏土渗透系数及其各向异性[J].岩土力学,2018,39(6):2139-2144.SONG Yun-qi,WU Chao-jun,YE Guan-lin.Permeability and anisotropy of upper Shanghai clays[J].Rock and Soil Mechanics,2018,39(6):2139-2144.
[14]SEAH T H,JUIRNARONGRIT T.Constant rate of strain consolidation with radial drainage[J].Geotechnical Testing Journal,2003,26(4):1-12.
[15]YUNE C Y,CHUNG C K.Consolidation test at constant rate of strain for radial drainage[J].Geotechnical Testing Journal,2005,28(1):71-78.
[16]LEROUEIL S.Tenth Canadian Geotechnical Colloquium:Recent developments in consolidation of natural clays[J].Canadian Geotechnical Journal,1988,25(1):85-107.
[17]加瑞,雷华阳.有明黏土固结特性的应变率效应和应变率取值研究[J].岩土工程学报,2017,39(增刊2):198-202.JIA Rui,LEI Hua-yang.Effect of strain rate on consolidation behavior of Ariake clay and selection of the suitable strain rate[J].Chinese Journal of Geotechnical Engineering,2017,39(Suppl.2):198-202.
[18]HINO T,IGAYA Y,SHIMOYAMA S,et al.Introduction of problem soil of Kyushu/Okinawa(1)-Ariake clay[J].Japanese Geotechnical Society,2010,58(6):6-9.
[19]MAYNE P E,KULHAWY F H.K0-OCR relationships in soil[J].Journal of the Geotechnical Engineering Division,1982,108(6):851-872.
[20]WHEELER S J,N??T?NEN A,KARSTUNEN M,et al.An anisotropic elastoplastic model for soft clays[J].Canadian Geotechnical Journal,2003,40(2):403-418.
[2]MITCHELL J K,SOGA K.Fundamentals of soil behavior[M].New York:Wiley,2005.
[3]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.
[4]钱家欢,殷宗泽.土工原理与计算[M].2版.北京:中国水利水电出版社,1996.QIAN Jia-huan,YIN Zong-zhe.The principle of soil engineering and calculation[M].2nd ed.Beijing:China Water&Power Press,1996.
[5]袁聚云.软土各向异性性状的试验研究及其在工程中的应用[D].上海:同济大学,1995.YUAN Ju-yun.Test study on soft soil’s anisotropy and its application to practice[D].Shanghai:Tongji University,1995.
[6]CALLISTO L,CALABRESI G.Mechanical behaviour of a natural soft clay[J].Geotechnique,1998,48(4):495-513.
[7]沈扬.考虑主应力方向变化的原状软黏土试验研究[D].杭州:浙江大学,2007.SHEN Yang.Experimental study on effect of variation of principal stress orientation on undisturbed soft clay[D].Hangzhou:Zhejiang University,2007.
[8]GASPARRE A,NISHIMURA S,MINH N A,et al.The stiffness of natural London clay[J].Geotechnique,2007,57(1):33-47.
[9]NISHIMURA S,MINH N A,JARDINE R J.Shear strength anisotropy of natural London clay[J].Geotechnique,2007,57(1):49-62.
[10]艾智勇,董洲,成怡冲,等.三维渗透各向异性层状地基Biot固结分析[J].土木工程学报,2011,44(12):79-84.AI Zhi-yong,DONG Zhou,CHENG Yi-chong,et al.Analysis of three-dimensional Biot’s consolidation of layered soils with anisotropic permeability[J].China Civil Engineering Journal,2011,44(12):79-84.
[11]O’KELLY B C.Compression and consolidation anisotropy of some soft soils[J].Geotechnical and Geological Engineering,2006,24:1715-1728.
[12]WONG L S.Laboratory evaluation of horizontal coefficient of consolidation ch of fibrous peat soil[D].Malaysia:University of Malaya,2005.
[13]宋云奇,武朝军,叶冠林.上海浅部黏土渗透系数及其各向异性[J].岩土力学,2018,39(6):2139-2144.SONG Yun-qi,WU Chao-jun,YE Guan-lin.Permeability and anisotropy of upper Shanghai clays[J].Rock and Soil Mechanics,2018,39(6):2139-2144.
[14]SEAH T H,JUIRNARONGRIT T.Constant rate of strain consolidation with radial drainage[J].Geotechnical Testing Journal,2003,26(4):1-12.
[15]YUNE C Y,CHUNG C K.Consolidation test at constant rate of strain for radial drainage[J].Geotechnical Testing Journal,2005,28(1):71-78.
[16]LEROUEIL S.Tenth Canadian Geotechnical Colloquium:Recent developments in consolidation of natural clays[J].Canadian Geotechnical Journal,1988,25(1):85-107.
[17]加瑞,雷华阳.有明黏土固结特性的应变率效应和应变率取值研究[J].岩土工程学报,2017,39(增刊2):198-202.JIA Rui,LEI Hua-yang.Effect of strain rate on consolidation behavior of Ariake clay and selection of the suitable strain rate[J].Chinese Journal of Geotechnical Engineering,2017,39(Suppl.2):198-202.
[18]HINO T,IGAYA Y,SHIMOYAMA S,et al.Introduction of problem soil of Kyushu/Okinawa(1)-Ariake clay[J].Japanese Geotechnical Society,2010,58(6):6-9.
[19]MAYNE P E,KULHAWY F H.K0-OCR relationships in soil[J].Journal of the Geotechnical Engineering Division,1982,108(6):851-872.
[20]WHEELER S J,N??T?NEN A,KARSTUNEN M,et al.An anisotropic elastoplastic model for soft clays[J].Canadian Geotechnical Journal,2003,40(2):403-418.