宁波海相软弱土层人工冻土强度特性试验
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摘要
人工冻土强度特性具有区域性,以宁波轨道交通2号线3种海相典型土质(淤泥质黏土、粉质黏土和粉土)开展冻土单轴抗压和三轴剪切试验研究。结果表明:3种土质在不同温度下试样均为腰鼓形塑性破坏,应力-应变曲线基本呈应变硬化型,但随温度降低有向应变软化转变的趋势;单轴抗压强度和弹性模量均随温度降低而近似线性增大;重塑粉质黏土抗压强度和弹性模量均与应变速率呈幂函数关系增长;各土质最大轴向偏应力随围压的增大而增大,且具有线性关系,-10℃抗剪强度指标(c、φ)均得到大幅提高,黏聚力提高1.23~1.76MPa;宁波地区典型粉质黏土与其他地区类似地层相比,单轴抗压和抗剪强度均较低,而弹性模量偏中等,与上海地区同类土质接近。
The strength of artificial frozen soil has regional characteristics.In this study,the uniaxial compressive strength test and triaxial shear strength test of frozen soils were carried out on three types of typical marine soils(muddy clay,silty clay and silt) in No.2 Line of Ningbo Rail Transit.The results showed that three types of soil samples at different temperatures were all drum-shaped plastic failure,and the stress-strain curves substantially assumed the strain hardening form,but the strain tended to soften with the decrease of the temperature.The uniaxial compressive strength and elastic modulus of each soil were increased linearly with the decreasing temperature,and the uniaxial compressive strength of silty clay was most affected by temperature(the temperature reduced by 1℃,and the strength increased by 0.3 MPa).At the strain rate of 10%/min,the uniaxial compressive strength of remolded silty clay was about8% higher than that of the undisturbed silty clay,and the elastic modulus was about 7% lower than that of the undisturbed silty clay.The compressive strength and elastic modulus of the remolded silty clay all increased with the power function of the strain rate.The maximal axial deviator stresses of the three soils increased linearly with the increase of confining pressure,and the order of maximum axial deviator stresses of different soils was silt > silty clay>muddy clay.The shear strength index(c,φ) at-10℃ was significantly improved compared with the normal temperature in particular,and the cohesion increased by nearly 1.23-1.76 MPa.The typical silty clay in Ningbo was compared with those of similar stratum in other areas(Nanjing City and Shanghai City).The uniaxial compressive strength and shear strength were relatively low,while the elastic modulus was moderate,which was close to those of Shanghai.
The strength of artificial frozen soil has regional characteristics.In this study,the uniaxial compressive strength test and triaxial shear strength test of frozen soils were carried out on three types of typical marine soils(muddy clay,silty clay and silt) in No.2 Line of Ningbo Rail Transit.The results showed that three types of soil samples at different temperatures were all drum-shaped plastic failure,and the stress-strain curves substantially assumed the strain hardening form,but the strain tended to soften with the decrease of the temperature.The uniaxial compressive strength and elastic modulus of each soil were increased linearly with the decreasing temperature,and the uniaxial compressive strength of silty clay was most affected by temperature(the temperature reduced by 1℃,and the strength increased by 0.3 MPa).At the strain rate of 10%/min,the uniaxial compressive strength of remolded silty clay was about8% higher than that of the undisturbed silty clay,and the elastic modulus was about 7% lower than that of the undisturbed silty clay.The compressive strength and elastic modulus of the remolded silty clay all increased with the power function of the strain rate.The maximal axial deviator stresses of the three soils increased linearly with the increase of confining pressure,and the order of maximum axial deviator stresses of different soils was silt > silty clay>muddy clay.The shear strength index(c,φ) at-10℃ was significantly improved compared with the normal temperature in particular,and the cohesion increased by nearly 1.23-1.76 MPa.The typical silty clay in Ningbo was compared with those of similar stratum in other areas(Nanjing City and Shanghai City).The uniaxial compressive strength and shear strength were relatively low,while the elastic modulus was moderate,which was close to those of Shanghai.
引文
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[2]李洪升,杨海天,常成,等.冻土抗压强度对应变速率敏感性分析[J].冰川冻土,1995,17(1):40-48.LI H S,YANG H T,CHANG C,et al.The strain rate sensitivity analysis of compression strength of frozen soil[J].Journal of Glaciology and Geocryology,1995,17(1):40-48.
[3]陈有亮,常乐群,徐珊,等.上海冻结软土的单轴抗压强度试验[J].上海大学学报(自然科学版),2009,15(3):310-315.CHEN Y L,CHANG L Q,XU S,et al.Experimental study on uniaxial compressive strength of Shanghai's frozen soils[J].Journal of Shanghai University(Natural Science Edition),2009,15(3):310-315.
[4]肖海斌.人工冻土单轴抗压强度与温度和含水率的关系[J].岩土工程界,2008,11(4):62-63,76.
[5]蔡正银,吴志强,黄英豪,等.含水率和含盐量对冻土无侧限抗压强度影响的试验研究[J].岩土工程学报,2014,36(9):1580-1586.CAI Z Y,WU Z Q,HUANG Y H,et al.Influence of water and salt contents on strength of frozen soils[J].Chinese Journal of Geotechnical Engineering,2014,36(9):1580-1586.
[6]HASS H,JAGOW-KLAFF R,WERNECKE R.Influence of salinity on the strength of various frozen soils[C]//13th International Conference on Cold Regions Engineering.Orono:American Society of Civil Engineers,2006.
[7]杨平.原状土与冻融土物理力学性能差异性研究[J].南京林业大学学报(自然科学版),2001,25(2):68-70.YANG P.Study on the difference of physical and mechanical properties between original and thawing soil[J].Journal of Nanjing Forestry University(Natural Sciences Edition),2001,25(2):68-70.
[8]贺俊,杨平,何文龙.苏州地铁典型土层冻土力学特性研究[J].水文地质工程地质,2010,37(5):72-76.HE J,YANG P,HE W L.Mechanical behavior research of typical frozen soil clay in Suzhou subway[J].Hydrogeology and Engineering Geology,2010,37(5):72-76.
[9]孙谷雨,杨平,刘贯荣.南京地区冻结粉质黏土邓肯-张模型参数试验研究[J].岩石力学与工程学报,2014,33(S1):2989-2995.SUN G Y,YANG P,LIU G R.Experimental test on constitutive relationship of Nanjing frozen silty clay considering Duncan-Chang model[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(S1):2989-2995.
[10]孙星亮,汪稔,胡明鉴,等.低围压下冻结粉质粘土的三轴强度及变形分析[J].岩土力学,2005,26(10):1623-1627.SUN X L,WANG R,HU M J,et al.Triaxial strength and deformation properties of frozen silty clay under low confining pressure[J].Rock and Soil Mechanics,2005,26(10):1623-1627.
[11]牛亚强,赖远明,王旭,等.冻结粉质黏土三轴抗压强度和变形特性试验研究[J].冰川冻土,2016,38(2):424-430.NIU Y Q,LAI Y M,WANG X,et al.Experimental study on triaxial compressive strength and deformation behaviors of frozen silty clay[J].Journal of Glaciology and Geocryology,2016,38(2):424-430.
[12]马巍,吴紫汪,盛煜.围压对冻土强度特性的影响[J].岩土工程学报,1995,17(5):7-11.MA W,WU Z W,SHENG Y.Effect of confining pressure on strength behavior of frozen soil[J].Chinese Journal of Geotechnical Engineering,1995,17(5):7-11.
[13]贺俊.苏州地铁典型土层冻土物理力学特性研究[D].南京:南京林业大学,2010.HE J.Study on physical and mechanical properties of frozen soil in Suzhou subway[D].Nanjing:Nanjing Forestry University,2010.
[14]牛江宇,靳鹏伟,李栋伟,等.冻结盐渍砂土单轴强度特性研究[J].冰川冻土,2015,37(2):428-433.NIU J Y,JIN P W,LI D W,et al.Study of the uniaxial compressive strength of frozen saline sandy soil[J].Journal of Glaciology and Geocryology,2015,37(2):428-433.
[15]杨平,张婷.城市地下工程人工冻结法理论与实践[M].北京:科学出版社,2015:39-80.
[2]李洪升,杨海天,常成,等.冻土抗压强度对应变速率敏感性分析[J].冰川冻土,1995,17(1):40-48.LI H S,YANG H T,CHANG C,et al.The strain rate sensitivity analysis of compression strength of frozen soil[J].Journal of Glaciology and Geocryology,1995,17(1):40-48.
[3]陈有亮,常乐群,徐珊,等.上海冻结软土的单轴抗压强度试验[J].上海大学学报(自然科学版),2009,15(3):310-315.CHEN Y L,CHANG L Q,XU S,et al.Experimental study on uniaxial compressive strength of Shanghai's frozen soils[J].Journal of Shanghai University(Natural Science Edition),2009,15(3):310-315.
[4]肖海斌.人工冻土单轴抗压强度与温度和含水率的关系[J].岩土工程界,2008,11(4):62-63,76.
[5]蔡正银,吴志强,黄英豪,等.含水率和含盐量对冻土无侧限抗压强度影响的试验研究[J].岩土工程学报,2014,36(9):1580-1586.CAI Z Y,WU Z Q,HUANG Y H,et al.Influence of water and salt contents on strength of frozen soils[J].Chinese Journal of Geotechnical Engineering,2014,36(9):1580-1586.
[6]HASS H,JAGOW-KLAFF R,WERNECKE R.Influence of salinity on the strength of various frozen soils[C]//13th International Conference on Cold Regions Engineering.Orono:American Society of Civil Engineers,2006.
[7]杨平.原状土与冻融土物理力学性能差异性研究[J].南京林业大学学报(自然科学版),2001,25(2):68-70.YANG P.Study on the difference of physical and mechanical properties between original and thawing soil[J].Journal of Nanjing Forestry University(Natural Sciences Edition),2001,25(2):68-70.
[8]贺俊,杨平,何文龙.苏州地铁典型土层冻土力学特性研究[J].水文地质工程地质,2010,37(5):72-76.HE J,YANG P,HE W L.Mechanical behavior research of typical frozen soil clay in Suzhou subway[J].Hydrogeology and Engineering Geology,2010,37(5):72-76.
[9]孙谷雨,杨平,刘贯荣.南京地区冻结粉质黏土邓肯-张模型参数试验研究[J].岩石力学与工程学报,2014,33(S1):2989-2995.SUN G Y,YANG P,LIU G R.Experimental test on constitutive relationship of Nanjing frozen silty clay considering Duncan-Chang model[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(S1):2989-2995.
[10]孙星亮,汪稔,胡明鉴,等.低围压下冻结粉质粘土的三轴强度及变形分析[J].岩土力学,2005,26(10):1623-1627.SUN X L,WANG R,HU M J,et al.Triaxial strength and deformation properties of frozen silty clay under low confining pressure[J].Rock and Soil Mechanics,2005,26(10):1623-1627.
[11]牛亚强,赖远明,王旭,等.冻结粉质黏土三轴抗压强度和变形特性试验研究[J].冰川冻土,2016,38(2):424-430.NIU Y Q,LAI Y M,WANG X,et al.Experimental study on triaxial compressive strength and deformation behaviors of frozen silty clay[J].Journal of Glaciology and Geocryology,2016,38(2):424-430.
[12]马巍,吴紫汪,盛煜.围压对冻土强度特性的影响[J].岩土工程学报,1995,17(5):7-11.MA W,WU Z W,SHENG Y.Effect of confining pressure on strength behavior of frozen soil[J].Chinese Journal of Geotechnical Engineering,1995,17(5):7-11.
[13]贺俊.苏州地铁典型土层冻土物理力学特性研究[D].南京:南京林业大学,2010.HE J.Study on physical and mechanical properties of frozen soil in Suzhou subway[D].Nanjing:Nanjing Forestry University,2010.
[14]牛江宇,靳鹏伟,李栋伟,等.冻结盐渍砂土单轴强度特性研究[J].冰川冻土,2015,37(2):428-433.NIU J Y,JIN P W,LI D W,et al.Study of the uniaxial compressive strength of frozen saline sandy soil[J].Journal of Glaciology and Geocryology,2015,37(2):428-433.
[15]杨平,张婷.城市地下工程人工冻结法理论与实践[M].北京:科学出版社,2015:39-80.