重塑高岭土渗透各向异性影响因素
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摘要
为了研究软土渗透各向异性,以重塑高岭土为研究对象,利用三轴渗流仪对重塑高岭土展开一系列渗流试验,研究电解质类型、浓度及固结压力对软黏土渗透各向异性的影响,并从微观角度解释其作用机理。研究发现:1)高岭土颗粒为扁平状结构,在一维固结下颗粒趋向于垂直于主应力方向排列,重塑高岭土竖向剖面孔隙面积大于水平向剖面孔隙面积,这2个因素共同导致渗透各向异性比(水平渗透系数与垂直渗透系数之比)大于1;2)渗透各向异性比随固结压力增大而减小,主要是因为竖向剖面大孔隙较多,压力作用下竖向剖面孔隙面积减小幅度大于水平剖面孔隙面积减小幅度;3)马来西亚高岭土在高纯水下为絮凝状结构,在盐溶液下为散凝状结构,在高纯水下土体竖向剖面大孔隙较多,而在盐溶液下竖向剖面孔隙和水平向剖面孔隙较为接近,导致在高纯水下测得的渗透各向异性比在盐溶液下的测量结果大;4)在本试验条件下,电解质类型、浓度对马来西亚高岭土渗透各向异性比的影响均较小。
A series of experiments were conducted by triaxial permeameter to analysis the permeability anisotropy of soft soil. The effects of electrolyte type, ionic molar concentration and consolidation pressure on permeability anisotropy and the corresponding microscopic mechanisms were investigated, with remolded kaolin as the research object. Results showed that under one-dimensional consolidation, kaolin particles, most having flat structure, tended to orientate perpendicularly to the direction of the major principal stress and the pore area of remolded kaolin in vertical profile was much larger than that in horizontal profile. As a result, permeability anisotropy ratio (ratio of horizontal to vertical permeability coefficients) was greater than one. Permeability anisotropy ratio decreased with the increase of consolidation pressure, of which the main reason was that the amount of large pores, which had higher compressibility, in vertical profile was larger than that in horizontal profile. Malaysia kaolin has flocculated structure if prepared in ultrapure water, while has dispersed structure in saline solution. The measured permeability anisotropy ratio in ultrapure water was larger than that in saline solution, which was the consequence of more large pores in vertical profile than that in horizontal profile in ultrapure water. The vertical and horizontal profiles had similar amounts of large pores in saline solution. Test results also revealed that the electrolyte type and ionic molar concentration had little effect on the permeability anisotropy ratio of Malaysia kaolin.
A series of experiments were conducted by triaxial permeameter to analysis the permeability anisotropy of soft soil. The effects of electrolyte type, ionic molar concentration and consolidation pressure on permeability anisotropy and the corresponding microscopic mechanisms were investigated, with remolded kaolin as the research object. Results showed that under one-dimensional consolidation, kaolin particles, most having flat structure, tended to orientate perpendicularly to the direction of the major principal stress and the pore area of remolded kaolin in vertical profile was much larger than that in horizontal profile. As a result, permeability anisotropy ratio (ratio of horizontal to vertical permeability coefficients) was greater than one. Permeability anisotropy ratio decreased with the increase of consolidation pressure, of which the main reason was that the amount of large pores, which had higher compressibility, in vertical profile was larger than that in horizontal profile. Malaysia kaolin has flocculated structure if prepared in ultrapure water, while has dispersed structure in saline solution. The measured permeability anisotropy ratio in ultrapure water was larger than that in saline solution, which was the consequence of more large pores in vertical profile than that in horizontal profile in ultrapure water. The vertical and horizontal profiles had similar amounts of large pores in saline solution. Test results also revealed that the electrolyte type and ionic molar concentration had little effect on the permeability anisotropy ratio of Malaysia kaolin.
引文
[1]刘正义.软黏土屈服特性及各向异性屈服面方程研究[D].杭州:浙江大学,2014:6-9.LIU Zheng-yi.Study on yielding characteristics and anisotropic yield surface equation of soft clay[D].Hangzhou:Zhejiang University,2014:6-9.
[2]柯瀚,吴小雯,张俊,等.基于优势流及各向异性随上覆压力变化的填埋体饱和渗流模型[J].岩土工程学报,2016,38(11):957-1964.KE Han,WU Xiao-wen,ZHANG Jun,et al.Modeling saturated permeability of municipal solid waste based on compression change of its preferential flow and anisotropy[J].Chinese Journal of Geotechnical Engineering,2016,38(11):957-1964.
[3]ZHANG D M,MA L X,ZHANG J,et al.Ground and tunnel responses induced by partial leakage in saturated clay with anisotropic permeability[J].Engineering Geology,2015,189:104-115.
[4]LEROUEIL S,BOUCLIN G,TAVENAS F,et al.Permeability anisotropy of natural clays as a function of strain[J].Canadian Geotechnical Journal,1990,27(5):568-579.
[5]TAVENAS F,JEAN P,LEBLOND P,et al.The permeability of natural soft clays.part II:permeability characteristics[J].Canadian Geotechnical Journal,1983,20(4):645-660.
[6]ADAMS A L,GERMAINE J T,FLEMINGS P B,et al.Stress induced permeability anisotropy of Resedimented Boston Blue Clay[J].Water Resources Research,2013,49(10):6561-6571.
[7]ADAMS A L,TAYLOR J,NORDQUIST,et al.Permeability anisotropy and resistivity anisotropy of mechanically compressed mud rocks[J].Canadian Geotechnical Journal,2016,53(9):1474-1482.
[8]REN X W,SANTAMARINA J C.The hydraulic conductivity of sediments:a pore size perspective[J].Engineering Geology,2018,233:48-54.
[9]CHAPUIS R P.Predicting the saturated hydraulic conductivity of soils:a review[J].Bulletin of Engineering Geology and the Environment,2012,71(3):401-434.
[10]曾玲玲,洪振舜,陈福全.压缩过程中重塑黏土渗透系数的变化规律[J].岩土力学,2012,33(5):1286-1292.ZENG Ling-ling,HONG Zhen-shun,CHEN Fu-quan.A law of change in permeability coefficient during compression of remolded clays[J].Rock and Soil Mechanics,2012,33(5):1286-1292.
[11]邓永锋,刘松玉,章定文,等.几种孔隙比与渗透系数关系的对比[J].西北地震工程学报,2011,33(增1):64-66.DENG Yong-feng,LIU Song-yu,ZHANG Ding-wen,et al.Comparison among some relationships between permeability and void ratio[J].Northwestern Seismologi Journal,2011,33(Suppl.1):64-66.
[12]HORPIBULSUK S,YANGSUKKASEAM N,CHINKULKIJNIWAT A,et al.Compressibility and permeability of Bangkok clay compared with kaolinite and bentonite[J].Applied Clay Science,2011,52(1/2):150-159.
[13]SPAGNOLI G,RUBINOS D,STANJEK H,et al.Undrained shear strength of clays as modified by pHvariations[J].Bulletin of Engineering Geology and the Environment,2012,71(1):135-148.
[14]王宝峰.孔隙溶液环境对黏土力学特性影响的试验研究[D].杭州:浙江大学,2017:19-31.WANG Bao-feng.Experimental study on the effect of pore fluid properties on the clay mechanical characteristics[D].Hangzhou:Zhejiang University,2017:19-31.
[15]ZAKERI A,CLUKEY E C,KEBADZE E B,et al.Fatigue analysis of offshore well conductors.part I:study overview and evaluation of series 1 centrifuge tests in normally consolidated to lightly overconsolidated kaolin clay[J].Applied Ocean Research,2016,57:78-95.
[16]HODDER M S,CASSIDY M J.A plasticity model for predicting the vertical and lateral behaviour of pipelines in clay soils[J].Geotechnique,2010,60(4):247-263.
[17]ASTM.Standard test methods for measurement of hydraulic conductivity of saturated porous materials using a flexible wall permeameter:D5084-03[S].West Conshohocken:ASTM,2003:1-12.
[18]REN X,ZHAO Y,DENG Q,et al.A relation of hydraulic conductivity-void ratio for soils based on Kozeny-carman equation[J].Engineering Geology,2016,213:89-97.
[19]BENHUR M,YOLCU G,UYSAL H,et al.Soil structure changes:aggregate size and soil texture effects on hydraulic conductivity under different saline and sodic conditions[J].Australian Journal of Soil Research,2015,47(7):688-696.
[20]PILLAI R J,ROBINSON R G,BOOMINATHAN A.Effect of microfabric on undrained static and cyclic behavior of kaolin clay[J].Journal of Geotechnical and Geoenvironmental Engineering,2011,137(4):421-429.
[21]WAHID A S,GAJO A,MAGGIO R.Chemomechanical effects in kaolinite.partⅡ:exposed samples chemical and phase analyses[J].Géotechnique,2011,61(6):449-457.
[22]MAGGIO R D,GAJO A,WAHID A S.Chemomechanical effects in kaolinite.partⅠ:prepared samples[J].Géotechnique,2011,61(6):439-447.
[23]LIN H,PENUMADU D.Experimental investigation on principal stress rotation in kaolin clay[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(5):633-642.
[24]KENNEY T C.Permeability ratio of repeatedly layered soils[J].Géotechnique,1963,13(4):325-333.
[25]WANG Y H,SIU W K.Structure characteristics and mechanical properties of kaolinite soils.I.surface charges and structural characterizations[J].Canadian Geotechnical Journal,2006,43:601-617.
[26]曹洋.波浪作用下原状软粘土动力特性与微观结构关系试验研究[D].杭州:浙江大学,2013:22-28.CAO Yang.Experimental study on the relationship of dynamic characteristics and microstructure of intact soft under wave loading[D].Hangzhou:Zhejiang University,2013:22-28.
[27]冯晓腊,沈孝宇.饱和粘性土的渗透固结特性及其微观机制的研究[J].水文地质工程地质,1991(1):6-12.FENG Xiao-la,SHEN Xiao-yu.Permeability consolidation characteristics of saturated cohesive soil and its micro-mechanics[J].Hydrogeology and Engineering Geology,1991(1):6-12.
[28]陈宝,朱嵘,常防震.不同压应力作用下黏土体积变形的微观特征[J].岩土力学,2011(增1):95-99.CHEN Bao,ZHU Rong,CHANG Fang-zhen.Microstructural characteristics of volumetric deformation of clay under different compression stresses[J].Rock and Soil Mechanics,2011,32(Suppl.1):95-99.
[29]SCHMITZ R M,SCHROEDER C,CHARLIER R.Chemo-mechanical interactions in clay:a correlation between clay mineralogy and Atterberg limits[J].Applied Clay Science,2004,26(1-4):351-358.
[30]MORENO-MAROTO J M,ALONSO-AZCáRATE J.An accurate,quick and simple method to determine the plastic limit and consistency changes in all types of clay and soil:the thread bending test[J].Applied Clay Science,2015,114:497-508.
[2]柯瀚,吴小雯,张俊,等.基于优势流及各向异性随上覆压力变化的填埋体饱和渗流模型[J].岩土工程学报,2016,38(11):957-1964.KE Han,WU Xiao-wen,ZHANG Jun,et al.Modeling saturated permeability of municipal solid waste based on compression change of its preferential flow and anisotropy[J].Chinese Journal of Geotechnical Engineering,2016,38(11):957-1964.
[3]ZHANG D M,MA L X,ZHANG J,et al.Ground and tunnel responses induced by partial leakage in saturated clay with anisotropic permeability[J].Engineering Geology,2015,189:104-115.
[4]LEROUEIL S,BOUCLIN G,TAVENAS F,et al.Permeability anisotropy of natural clays as a function of strain[J].Canadian Geotechnical Journal,1990,27(5):568-579.
[5]TAVENAS F,JEAN P,LEBLOND P,et al.The permeability of natural soft clays.part II:permeability characteristics[J].Canadian Geotechnical Journal,1983,20(4):645-660.
[6]ADAMS A L,GERMAINE J T,FLEMINGS P B,et al.Stress induced permeability anisotropy of Resedimented Boston Blue Clay[J].Water Resources Research,2013,49(10):6561-6571.
[7]ADAMS A L,TAYLOR J,NORDQUIST,et al.Permeability anisotropy and resistivity anisotropy of mechanically compressed mud rocks[J].Canadian Geotechnical Journal,2016,53(9):1474-1482.
[8]REN X W,SANTAMARINA J C.The hydraulic conductivity of sediments:a pore size perspective[J].Engineering Geology,2018,233:48-54.
[9]CHAPUIS R P.Predicting the saturated hydraulic conductivity of soils:a review[J].Bulletin of Engineering Geology and the Environment,2012,71(3):401-434.
[10]曾玲玲,洪振舜,陈福全.压缩过程中重塑黏土渗透系数的变化规律[J].岩土力学,2012,33(5):1286-1292.ZENG Ling-ling,HONG Zhen-shun,CHEN Fu-quan.A law of change in permeability coefficient during compression of remolded clays[J].Rock and Soil Mechanics,2012,33(5):1286-1292.
[11]邓永锋,刘松玉,章定文,等.几种孔隙比与渗透系数关系的对比[J].西北地震工程学报,2011,33(增1):64-66.DENG Yong-feng,LIU Song-yu,ZHANG Ding-wen,et al.Comparison among some relationships between permeability and void ratio[J].Northwestern Seismologi Journal,2011,33(Suppl.1):64-66.
[12]HORPIBULSUK S,YANGSUKKASEAM N,CHINKULKIJNIWAT A,et al.Compressibility and permeability of Bangkok clay compared with kaolinite and bentonite[J].Applied Clay Science,2011,52(1/2):150-159.
[13]SPAGNOLI G,RUBINOS D,STANJEK H,et al.Undrained shear strength of clays as modified by pHvariations[J].Bulletin of Engineering Geology and the Environment,2012,71(1):135-148.
[14]王宝峰.孔隙溶液环境对黏土力学特性影响的试验研究[D].杭州:浙江大学,2017:19-31.WANG Bao-feng.Experimental study on the effect of pore fluid properties on the clay mechanical characteristics[D].Hangzhou:Zhejiang University,2017:19-31.
[15]ZAKERI A,CLUKEY E C,KEBADZE E B,et al.Fatigue analysis of offshore well conductors.part I:study overview and evaluation of series 1 centrifuge tests in normally consolidated to lightly overconsolidated kaolin clay[J].Applied Ocean Research,2016,57:78-95.
[16]HODDER M S,CASSIDY M J.A plasticity model for predicting the vertical and lateral behaviour of pipelines in clay soils[J].Geotechnique,2010,60(4):247-263.
[17]ASTM.Standard test methods for measurement of hydraulic conductivity of saturated porous materials using a flexible wall permeameter:D5084-03[S].West Conshohocken:ASTM,2003:1-12.
[18]REN X,ZHAO Y,DENG Q,et al.A relation of hydraulic conductivity-void ratio for soils based on Kozeny-carman equation[J].Engineering Geology,2016,213:89-97.
[19]BENHUR M,YOLCU G,UYSAL H,et al.Soil structure changes:aggregate size and soil texture effects on hydraulic conductivity under different saline and sodic conditions[J].Australian Journal of Soil Research,2015,47(7):688-696.
[20]PILLAI R J,ROBINSON R G,BOOMINATHAN A.Effect of microfabric on undrained static and cyclic behavior of kaolin clay[J].Journal of Geotechnical and Geoenvironmental Engineering,2011,137(4):421-429.
[21]WAHID A S,GAJO A,MAGGIO R.Chemomechanical effects in kaolinite.partⅡ:exposed samples chemical and phase analyses[J].Géotechnique,2011,61(6):449-457.
[22]MAGGIO R D,GAJO A,WAHID A S.Chemomechanical effects in kaolinite.partⅠ:prepared samples[J].Géotechnique,2011,61(6):439-447.
[23]LIN H,PENUMADU D.Experimental investigation on principal stress rotation in kaolin clay[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(5):633-642.
[24]KENNEY T C.Permeability ratio of repeatedly layered soils[J].Géotechnique,1963,13(4):325-333.
[25]WANG Y H,SIU W K.Structure characteristics and mechanical properties of kaolinite soils.I.surface charges and structural characterizations[J].Canadian Geotechnical Journal,2006,43:601-617.
[26]曹洋.波浪作用下原状软粘土动力特性与微观结构关系试验研究[D].杭州:浙江大学,2013:22-28.CAO Yang.Experimental study on the relationship of dynamic characteristics and microstructure of intact soft under wave loading[D].Hangzhou:Zhejiang University,2013:22-28.
[27]冯晓腊,沈孝宇.饱和粘性土的渗透固结特性及其微观机制的研究[J].水文地质工程地质,1991(1):6-12.FENG Xiao-la,SHEN Xiao-yu.Permeability consolidation characteristics of saturated cohesive soil and its micro-mechanics[J].Hydrogeology and Engineering Geology,1991(1):6-12.
[28]陈宝,朱嵘,常防震.不同压应力作用下黏土体积变形的微观特征[J].岩土力学,2011(增1):95-99.CHEN Bao,ZHU Rong,CHANG Fang-zhen.Microstructural characteristics of volumetric deformation of clay under different compression stresses[J].Rock and Soil Mechanics,2011,32(Suppl.1):95-99.
[29]SCHMITZ R M,SCHROEDER C,CHARLIER R.Chemo-mechanical interactions in clay:a correlation between clay mineralogy and Atterberg limits[J].Applied Clay Science,2004,26(1-4):351-358.
[30]MORENO-MAROTO J M,ALONSO-AZCáRATE J.An accurate,quick and simple method to determine the plastic limit and consistency changes in all types of clay and soil:the thread bending test[J].Applied Clay Science,2015,114:497-508.