黏粒含量对粉质黏土土水特性影响的试验研究
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摘要
粉质黏土分布广泛,其土水特性受黏粒含量影响显著。为揭示黏粒含量对粉质黏土土水特性的影响规律,采用离心机对不同黏粒含量粉质黏土进行脱水条件下土水特性测试试验。首先,制备六组干密度相同的不同黏粒含量粉质黏土试样,并通过密度计与筛分联合测定法获得试样颗粒级配曲线和黏粒含量。然后,通过调节离心机转速得到不同基质吸力对应的土样总质量与含水量,并基于Van-Genuchten模型拟合土样土-水特征曲线,进而分析黏粒含量对土-水特征曲线的影响。研究结果表明:(1)不同黏粒含量粉质黏土的体积含水率均随基质吸力增加逐渐减小且变化趋势基本一致:当基质吸力小于20 k Pa时,含水率接近饱和含水率,大于20 k Pa后含水率随基质吸力增加快速减小;(2)黏粒含量越高,粉质黏土持水能力越强,土体含水率越大,含水率受黏粒含量增加影响的程度呈现先增大后减小的趋势;(3)相同基质吸力条件下,黏粒含量越高,土体含水率越大,在基质吸力大于80 k Pa后不同黏粒含量土样的含水率相差越来越小;(4)残余含水率偏高,吸附的水分仍达到其饱和状态含水量的40%左右。这为进一步进行非饱和粉质黏土软基的水力特性评估提供了技术支持。
Silty clay is very common in geotechnical engineering and its soil water characteristics are affected by clay contents. To disclose the impacts of clay content on soil-water characteristics of silty clay,centrifuge tests for soil-water characteristics with silty clay samples of different clay contents were performed. Firstly,six silty clay samples with different clay contents and the same dry density were prepared and their particle size distributions and clay contents are determined with the densimeter method and the sieving method. Then,the corresponding soil moistures and weights of different matrix suctions are obtained by adjusting the speed of a centrifuge,and soil-water characteristic curves of six samples are fitted on Van-Genuchten model. The results show as follows.(1)The volumetric moisture contents of the clay with different clay contents decrease with the increase of matrix suction and their trends are the same: the volumetric moisture content varies little when the matric suction is less than 20 k Pa,which is close to the saturated water content,but decreases rapidly with the increase of matrix suction when the matrix suction is greater than 20 k Pa.(2)The higher the content of clay particles,the stronger the water retention capacity and saturated moisture content of silty clay,the greater its water content,as the clay content increases,the influence of clay content on moisture content first increases and then diminishes.(3)The large clay content corresponds to large water content of volume in the case of same soil suction,the volumetric moisture contents of silty clay with different clay contents vary smaller and smaller after the matrix suction is more than 80 k Pa.(4)The residual moisture content of silty clay is relatively higher,the residual moisture absorbed still reaches 40% of its saturated state. This provides a technical supporting for further evaluation of hydraulic and mechanical characteristics of unsaturated silty clay ground.
Silty clay is very common in geotechnical engineering and its soil water characteristics are affected by clay contents. To disclose the impacts of clay content on soil-water characteristics of silty clay,centrifuge tests for soil-water characteristics with silty clay samples of different clay contents were performed. Firstly,six silty clay samples with different clay contents and the same dry density were prepared and their particle size distributions and clay contents are determined with the densimeter method and the sieving method. Then,the corresponding soil moistures and weights of different matrix suctions are obtained by adjusting the speed of a centrifuge,and soil-water characteristic curves of six samples are fitted on Van-Genuchten model. The results show as follows.(1)The volumetric moisture contents of the clay with different clay contents decrease with the increase of matrix suction and their trends are the same: the volumetric moisture content varies little when the matric suction is less than 20 k Pa,which is close to the saturated water content,but decreases rapidly with the increase of matrix suction when the matrix suction is greater than 20 k Pa.(2)The higher the content of clay particles,the stronger the water retention capacity and saturated moisture content of silty clay,the greater its water content,as the clay content increases,the influence of clay content on moisture content first increases and then diminishes.(3)The large clay content corresponds to large water content of volume in the case of same soil suction,the volumetric moisture contents of silty clay with different clay contents vary smaller and smaller after the matrix suction is more than 80 k Pa.(4)The residual moisture content of silty clay is relatively higher,the residual moisture absorbed still reaches 40% of its saturated state. This provides a technical supporting for further evaluation of hydraulic and mechanical characteristics of unsaturated silty clay ground.
引文
1 Fredlund D G,Rahardjo H.Soil mechanics for unsaturated soils.Saskatoon:John Wiley and Sons INC,1993
2 Ning Lu,Willam J Likos.非饱和土土力学.北京:高等教育出版社,2012Ning Lu,Willam J Likos.Soil mechanics for unsaturated soils.Beijing:Higher Education Press,2012
3 梁文鹏,吴家琦,谭晔,等.基于土水特征曲线的非饱和土强度预测.科学技术与工程,2018;18(4):333—338Liang Wenpeng,Wu Jiaqi,Tan Ye,et al.Shear strength prediction of unsaturated soil based on soil-water characteristic curve.Science Technology and Engineering,2018;18(4):333—338
4 赵天宇,王锦芳.考虑密度与干湿循环影响的黄土土-水特征曲线.中南大学学报(自然科学版),2012;43(6):2445—2453Zhao Tianyu,Wang Jinfang.Soil-water characteristic curve for unsaturated loess soil considering density and wetting-drying cycle effects.Journal of Central South University(Natural Science Edition),2012;43 (6):2445—2453
5 王铁行,卢靖,岳彩坤,等.考虑温度和密度影响的非饱和黄土土-水特征曲线研究.岩土力学,2008;29(1):1—5Wang Tiehang,Lu Jing,Yue Caikun,et al.Soil-water characteristic curve for unsaturated loess considering temperature and density effect.Rock and Soil Mechanics,2008;29(1):1—5
6 伊盼盼,牛圣宽,韦昌富.干密度和初始含水率对非饱和重塑粉土土-水特征曲线的影响.水文地质工程地质,2012;39(1):42 —46Yi Panpan,Niu Shengkuan,Wei Changfu.Effect of dry density and initial moisture content on soil-water characteristic curve of remolded unsaturated silt.Hydrogeology and Engineerring Geology,2012;39(1):42—46
7 王协群,邹维列,骆以道,等.压实度与级配对路基重塑黏土土-水特征曲线的影响.岩土力学,2011;32(增刊1):181—184Wang Xiequn,Zou Weilie,Luo Yidao,et al.Influence of compaction degree and gradation on SWCC of compacted clay soil.Rock and Soil Mechanics,2011;32(S1):181—184
8 Brooks R H,Corey A T.Properties of porous media affecting fluid flow.Journal of the Irrigation and Drainage Engineering,1966;92(2):61—88
9 李宇晗.含水率及黏粒含量对非饱和土强度影响试验研究.南昌:华东交通大学,2014Li Yuhan.Experimental study of the moisture content and clay content on the strength of unsaturated soil.Nanchang:East China Jiaotong University,2014
10 陶高梁,张季如,庄新善,等.描述黏粒含量对土-水特征曲线影响规律的分形模型.水利学报,2014;45(4):490—496Tao Gaoliang,Zhang Jiru,Zhuang Xinshan,et al.A fractal model describing the relation between clay content and soil-water characteristic curve.Journal of Hydraulic Engineering,2014;45(4):490—496
11 李永乐,刘汉东,刘海宁,等.黄河大堤非饱和土土-水特性试验研究.岩土力学,2005;26(3):347—350Li Yongle,Liu Handong,Liu Haining,et al.Test and study on soil water curve of unsaturated soil of Yellow River dyke.Rock and Soil Mechanics,2005;26(3):347—350
12 胡孝彭,赵仲辉,倪晓雯.应力状态对土-水特征曲线的影响规律.河海大学学报(自然科学版),2013;41(2):150—155Hu Xiaopeng,Zhao Zhonghui,Ni Xiaowen.Influence of stress state on soil-water characteristic curve.Journal of Hohai University(Natural Science Edition),2013;41(2):150—155
13 左昌群,刘代国,丁少林,等.基于颗粒分形滑坡土体土水特征曲线评价及预测.科学技术与工程,2014;14(32):276—281Zuo Changqun,Liu Daiguo,Ding Shaolin,et al.Prediction and evaluation on soil water retention curve of landslide soil based on fractal of particles.Science Technology and Engineering,2014;14(32):276—281
14 汪为巍,易远,陆海军,等.南阳膨胀土土水特征曲线试验研究.科学技术与工程,2016;16(18):78—82Wang Weiwei,Yi Yuan,Lu Haijun,et al.The study of Nanyang expansive soil water characteristic curve.Science Technology and Engineering,2016;16(18):78—82
15 胡孝彭,赵仲辉.基于离心机法研究固化淤泥的土水特征曲线.水利与建筑工程学报,2014;12(2):5—8,57Hu Xiaopeng,Zhao Zhonghui.Study on Soil-water characteristic curve of solidified dredged material based on centrifuge method.Journal of Water Resources and Architectural Engineering,2014;12(2):5—8,57
16 Baker R,Frydman S.Unsaturated soil mechanics:Critical review of physical foundations.Engineering Geology,2009;106(1—2):26 —39
17 Van Genuchten M T.A closed-form equation for predicting the hydraulic conductivity of unsaturated soils.Soil Sciences Society of America Journal,1980;44(5):892—898
18 兰天.黏粒含量对粉质黏土岸坡渗流与稳定特性影响研究.长沙:长沙理工大学,2016Lan Tian.Study on impacts of clay content on bank slope sepage and stability characteristics of silty clay.Changsha:Changsha University of Science and Technology,2016
19 张晓腊,张睿敏,崔德山,等.基质吸力与黏粒含量对砂土抗剪强度的影响.科学技术与工程,2017;17(34):97—103Zhang Xiaola,Zhang Ruimin,Cui Deshan,et al.Influence of matrix suction and clay content on shear strength of clay sand.Science Technology and Engineering,2017;17(34):97—103
2 Ning Lu,Willam J Likos.非饱和土土力学.北京:高等教育出版社,2012Ning Lu,Willam J Likos.Soil mechanics for unsaturated soils.Beijing:Higher Education Press,2012
3 梁文鹏,吴家琦,谭晔,等.基于土水特征曲线的非饱和土强度预测.科学技术与工程,2018;18(4):333—338Liang Wenpeng,Wu Jiaqi,Tan Ye,et al.Shear strength prediction of unsaturated soil based on soil-water characteristic curve.Science Technology and Engineering,2018;18(4):333—338
4 赵天宇,王锦芳.考虑密度与干湿循环影响的黄土土-水特征曲线.中南大学学报(自然科学版),2012;43(6):2445—2453Zhao Tianyu,Wang Jinfang.Soil-water characteristic curve for unsaturated loess soil considering density and wetting-drying cycle effects.Journal of Central South University(Natural Science Edition),2012;43 (6):2445—2453
5 王铁行,卢靖,岳彩坤,等.考虑温度和密度影响的非饱和黄土土-水特征曲线研究.岩土力学,2008;29(1):1—5Wang Tiehang,Lu Jing,Yue Caikun,et al.Soil-water characteristic curve for unsaturated loess considering temperature and density effect.Rock and Soil Mechanics,2008;29(1):1—5
6 伊盼盼,牛圣宽,韦昌富.干密度和初始含水率对非饱和重塑粉土土-水特征曲线的影响.水文地质工程地质,2012;39(1):42 —46Yi Panpan,Niu Shengkuan,Wei Changfu.Effect of dry density and initial moisture content on soil-water characteristic curve of remolded unsaturated silt.Hydrogeology and Engineerring Geology,2012;39(1):42—46
7 王协群,邹维列,骆以道,等.压实度与级配对路基重塑黏土土-水特征曲线的影响.岩土力学,2011;32(增刊1):181—184Wang Xiequn,Zou Weilie,Luo Yidao,et al.Influence of compaction degree and gradation on SWCC of compacted clay soil.Rock and Soil Mechanics,2011;32(S1):181—184
8 Brooks R H,Corey A T.Properties of porous media affecting fluid flow.Journal of the Irrigation and Drainage Engineering,1966;92(2):61—88
9 李宇晗.含水率及黏粒含量对非饱和土强度影响试验研究.南昌:华东交通大学,2014Li Yuhan.Experimental study of the moisture content and clay content on the strength of unsaturated soil.Nanchang:East China Jiaotong University,2014
10 陶高梁,张季如,庄新善,等.描述黏粒含量对土-水特征曲线影响规律的分形模型.水利学报,2014;45(4):490—496Tao Gaoliang,Zhang Jiru,Zhuang Xinshan,et al.A fractal model describing the relation between clay content and soil-water characteristic curve.Journal of Hydraulic Engineering,2014;45(4):490—496
11 李永乐,刘汉东,刘海宁,等.黄河大堤非饱和土土-水特性试验研究.岩土力学,2005;26(3):347—350Li Yongle,Liu Handong,Liu Haining,et al.Test and study on soil water curve of unsaturated soil of Yellow River dyke.Rock and Soil Mechanics,2005;26(3):347—350
12 胡孝彭,赵仲辉,倪晓雯.应力状态对土-水特征曲线的影响规律.河海大学学报(自然科学版),2013;41(2):150—155Hu Xiaopeng,Zhao Zhonghui,Ni Xiaowen.Influence of stress state on soil-water characteristic curve.Journal of Hohai University(Natural Science Edition),2013;41(2):150—155
13 左昌群,刘代国,丁少林,等.基于颗粒分形滑坡土体土水特征曲线评价及预测.科学技术与工程,2014;14(32):276—281Zuo Changqun,Liu Daiguo,Ding Shaolin,et al.Prediction and evaluation on soil water retention curve of landslide soil based on fractal of particles.Science Technology and Engineering,2014;14(32):276—281
14 汪为巍,易远,陆海军,等.南阳膨胀土土水特征曲线试验研究.科学技术与工程,2016;16(18):78—82Wang Weiwei,Yi Yuan,Lu Haijun,et al.The study of Nanyang expansive soil water characteristic curve.Science Technology and Engineering,2016;16(18):78—82
15 胡孝彭,赵仲辉.基于离心机法研究固化淤泥的土水特征曲线.水利与建筑工程学报,2014;12(2):5—8,57Hu Xiaopeng,Zhao Zhonghui.Study on Soil-water characteristic curve of solidified dredged material based on centrifuge method.Journal of Water Resources and Architectural Engineering,2014;12(2):5—8,57
16 Baker R,Frydman S.Unsaturated soil mechanics:Critical review of physical foundations.Engineering Geology,2009;106(1—2):26 —39
17 Van Genuchten M T.A closed-form equation for predicting the hydraulic conductivity of unsaturated soils.Soil Sciences Society of America Journal,1980;44(5):892—898
18 兰天.黏粒含量对粉质黏土岸坡渗流与稳定特性影响研究.长沙:长沙理工大学,2016Lan Tian.Study on impacts of clay content on bank slope sepage and stability characteristics of silty clay.Changsha:Changsha University of Science and Technology,2016
19 张晓腊,张睿敏,崔德山,等.基质吸力与黏粒含量对砂土抗剪强度的影响.科学技术与工程,2017;17(34):97—103Zhang Xiaola,Zhang Ruimin,Cui Deshan,et al.Influence of matrix suction and clay content on shear strength of clay sand.Science Technology and Engineering,2017;17(34):97—103