不同干密度重塑黄土的毛细上升速率和最大高度
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摘要
黄土的毛细上升现象会导致路基土干湿状态发生变化,使路基的强度降低或失稳,因此深入研究不同干密度重塑黄土的毛细上升速率与最大高度,得到改进的预测毛细上升速率的经验公式及不同干密度的重塑黄土毛细水的上升高度规律及区间,对减轻路基地质的灾害具有重要意义。试验使用竖管法测得了3组不同干密度的重塑黄土最大毛细上升高度。基于Green-Ampt非饱和入渗原理,改进了预测毛细上升速率的Terzaghi公式,使其预测效果明显改善。在此基础上,利用实测黄土毛细上升数据论证了Terzaghi公式和Lu公式对不同干密度重塑黄土毛细上升速率估算的适用性。结果表明,黄土干密度在1.59~1.77 g/cm~3区间时,改进的Terzaghi公式预测值更为准确,而当干密度继续增加,达到1.83 g/cm3时,Lu公式更为适用。另外,用15组数据对毛细最大上升高度与干密度之间的关系进行了分析,结果表明,毛细最大上升高度与干密度之间非线性关系,而是呈现近似抛物线的函数关系,基于这种关系将重塑黄土划分出优势干密度区间和劣势干密度区间,以更好地表征黄土毛细上升性能。
The phenomenon of capillary rise of loess can lead to the change of dry and wet states of subgrade soil,weaken or destabilize the strength of roadbed. Therefore,this is of great significance to alleviate the geological disasters in the roadbed by further studying the capillary rise rate and the maximum height of the remolded loess with different dry densities to get an improved empirical formula for predicting the capillary rise rate and the rule of the rising height of remodeled loess capillary water with different dry densities. Three sets of maximum capillary rise height of remolded loess with different dry densities are measured by using vertical tube method. Based on the Green-Ampt unsaturated infiltration principle,the Terzaghi formula for predicting the capillary rise rate is improved,which improved the prediction result. On this basis,the applicability of the Terzaghi formula and the Lu formula to estimate the capillary rise rate of remolded loess with different dry densities is demonstrated by using the measured data of capillary rise experiment. The result shows that the modified Terzaghi formula is more accurate when the dry density is in the range of 1. 59-1. 77 g/cm~3,while the Lu formula is more applicable when the dry density continues to increase to 1. 83 g/cm~3. In addition,the relationship between maximum capillary rise height and dry density is analyzed with 15 sets of data. The result shows that the maximum capillary rise height and the dry density shows an approximate parabolic function rather than a linear relationship,and based on that,the dominant dry density interval and the inferior dry density interval of remodeled loess are divided to better characterize the capillary rise property of loess.
The phenomenon of capillary rise of loess can lead to the change of dry and wet states of subgrade soil,weaken or destabilize the strength of roadbed. Therefore,this is of great significance to alleviate the geological disasters in the roadbed by further studying the capillary rise rate and the maximum height of the remolded loess with different dry densities to get an improved empirical formula for predicting the capillary rise rate and the rule of the rising height of remodeled loess capillary water with different dry densities. Three sets of maximum capillary rise height of remolded loess with different dry densities are measured by using vertical tube method. Based on the Green-Ampt unsaturated infiltration principle,the Terzaghi formula for predicting the capillary rise rate is improved,which improved the prediction result. On this basis,the applicability of the Terzaghi formula and the Lu formula to estimate the capillary rise rate of remolded loess with different dry densities is demonstrated by using the measured data of capillary rise experiment. The result shows that the modified Terzaghi formula is more accurate when the dry density is in the range of 1. 59-1. 77 g/cm~3,while the Lu formula is more applicable when the dry density continues to increase to 1. 83 g/cm~3. In addition,the relationship between maximum capillary rise height and dry density is analyzed with 15 sets of data. The result shows that the maximum capillary rise height and the dry density shows an approximate parabolic function rather than a linear relationship,and based on that,the dominant dry density interval and the inferior dry density interval of remodeled loess are divided to better characterize the capillary rise property of loess.
引文
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[16]李锐,赵文光,陈善雄.基于GEO-SLOPE的膨胀土路基毛细水上升分析[J].华中科技大学学报:城市科学版,2006,23(增1):36-39.LI Rui,ZHAO Wen-guang,CHEN Shan-xiong.Capillary Water Upward Movement Analysis of Expansive Soil Roadbed Based on GEO-SLOPE[J].Journal of Huazhong University of Science and Technology:Urban Science Edition,2006,23(S1):36-39.
[17]周奇,陈太红,朱振南,等.黄土路基毛细上升规律试验模拟研究[J].烟台大学学报:自然科学与工程版,2015,28(1):54-60.ZHOU Qi,CHEN Tai-hong,ZHU Zhen-nan,et al.Numerical and Experimental Study on Capillary Rise of Phreatic Water in Loess Roadbed[J].Journal of Yantai University:Natural Science and Engineering Edition,2015,28(1):54-60.
[18]李先瑞,李晓媛,王圣麟.改性黄土垂直方向毛细水上升作用研究[J].建筑技术,2015,15(28):191-195.LI Xian-rui,LI Xiao-yuan,WANG Sheng-lin.Capillary Water Migration Effects of Modified Loess in Vertical Direction[J].Science Technology and Engineering,2015,15(28):191-195.
[19]王圣麟.改性黄土中毛细水上升作用研究[D].兰州:兰州大学,2015.WANG Sheng-lin.Moisture Migration Effects of Modified Loess in Vertical Direction[D].Lanzhou:Lanzhou University,2015.
[20]王素琴,陈晋中,刘松玉.粉质土毛细水上升高度及含水率分布的试验研究[J].路基工程,2015(5):81-83.WANG Su-qin,CHEN Jin-zhong,LIU Song-yu.On the Capillary Water Rising Height and the Moisture Content Distribution in the Silty Soil[J].Subgrade Engineering,2015(5):81-83.
[2]许淑珍.非饱和压实黄土毛细作用的试验研究[D].太原:太原理工大学,2016.XU Shu-zhen.Experimental Study on Capillary Effect in Unsaturated Compaction Loess[D].Taiyuan:Taiyuan University of Technology,2016.
[3]赵明华,刘小平,陈安.非饱和土路基毛细作用分析[J].公路交通科技,2008,25(8):26-30.ZHAO Ming-hua,LIU Xiao-ping,CHEN An.Analysis of Capillary Effect in Unsaturated Roadbed[J].Journal of Highway and Transportation Research and Development,2008,25(8):26-30.
[4]李锐.毛细水对膨胀土路基的影响研究及其处置对策[D].武汉:华中科技大学,2006.LI Rui.Study on Capillary Water’s Influence on Expansive Soil Subgrade and Its Treatment Measures[D].Wuhan:Huazhong University of Science and Technology,2006.
[5]刘巍然.压实黄土中含水量的分布及水分迁移规律研究[D].西安:长安大学,2004.LIU Wei-ran.Study on Water Content Distribution and Moisture Transfer Law of Compacted Loess[D].Xi’an:Chang’an University,2004.
[6]刘杰,姚海林,卢正.非饱和土路基毛细作用的数值与解析方法研究[J].岩土力学,2013,34(增2):421-427.LIU Jie,YAO Hai-lin,LU Zheng.Study of Analytic and Numerical Methods for Capillary Action of Unsaturated Soil Subgrade[J].Rock and Soil Mechanics,2013,34(S2):421-427.
[7]朱登元,管延华.毛细水作用对粉土路基稳定性的影响[J].山东大学学报:工学版,2012,42(1):93-98.ZHU Deng-yuan,GUAN Yan-hua.The Influence of Capillary Water Action on the Embankment Stability of a Silt Embankment[J].Journal of Shandong University:Engineering Science Edition,2012,42(1):93-98.
[8]贝尔J,李竞生,陈崇希.多孔介质流体动力学[M].北京:中国建筑工业出版社,1983.BEAR J,LI Jing-sheng,CHEN Chong-xi.Dynamics of Fluids in Porous Media[M].Beijing:China Architecture&Building Press,1983.
[9]TERZAGHI K.Theoretical Soil Mechanices[M].New York:Willey,1943.
[10]LU N,WILLIAM J,LIKOS.Unsaturated Soil Mechanics[M].New York:Wiley,2004.
[11]米海存,何红曼,段吉波.风干砂毛细上升实验研究[J].节水灌溉,2014(6):26-28.MI Hai-cun,HE Hong-man,DUAN Ji-bo.Experimental Study on Aeolian Sand Capillary Rise[J].Water Saving Irrigation,2014(6):26-28.
[12]李萍,李同录,侯晓坤,等.黄土中毛细上升速率的现场测试[J].河海大学学报:自然科学版,2014,42(6):504-507.LI Ping,LI Tong-lu,HOU Xiao-kun,et al.Field Experiment on Rate of Capillary Rise in Loess[J].Journal of Hohai University:Natural Science Edition,2014,42(6):504-507.
[13]胡欣.湿陷性黄土路基水分场及其变形特性数值分析[D].重庆:重庆交通大学,2016.HU Xin.Numerical Analysis on Moisture Field and Deformation Characteristics of Collapsible Loess Subgrade[D].Chongqing:Chongqing Jiaotong University,2016.
[14]雷志栋.土壤水动力学[M].北京:清华大学出版社,1988.LEI Zhi-dong.Soil Water Dynamics[M].Beijing:Tsinghua University Press,1988.
[15]BOUWER H.Rapid Field Measurement of Air Entry Value And Hydraulic Conductivity of Soil as Significant Parameters in Flow System Analysis[J].Water Resources Research,1966,2(4):729-738.
[16]李锐,赵文光,陈善雄.基于GEO-SLOPE的膨胀土路基毛细水上升分析[J].华中科技大学学报:城市科学版,2006,23(增1):36-39.LI Rui,ZHAO Wen-guang,CHEN Shan-xiong.Capillary Water Upward Movement Analysis of Expansive Soil Roadbed Based on GEO-SLOPE[J].Journal of Huazhong University of Science and Technology:Urban Science Edition,2006,23(S1):36-39.
[17]周奇,陈太红,朱振南,等.黄土路基毛细上升规律试验模拟研究[J].烟台大学学报:自然科学与工程版,2015,28(1):54-60.ZHOU Qi,CHEN Tai-hong,ZHU Zhen-nan,et al.Numerical and Experimental Study on Capillary Rise of Phreatic Water in Loess Roadbed[J].Journal of Yantai University:Natural Science and Engineering Edition,2015,28(1):54-60.
[18]李先瑞,李晓媛,王圣麟.改性黄土垂直方向毛细水上升作用研究[J].建筑技术,2015,15(28):191-195.LI Xian-rui,LI Xiao-yuan,WANG Sheng-lin.Capillary Water Migration Effects of Modified Loess in Vertical Direction[J].Science Technology and Engineering,2015,15(28):191-195.
[19]王圣麟.改性黄土中毛细水上升作用研究[D].兰州:兰州大学,2015.WANG Sheng-lin.Moisture Migration Effects of Modified Loess in Vertical Direction[D].Lanzhou:Lanzhou University,2015.
[20]王素琴,陈晋中,刘松玉.粉质土毛细水上升高度及含水率分布的试验研究[J].路基工程,2015(5):81-83.WANG Su-qin,CHEN Jin-zhong,LIU Song-yu.On the Capillary Water Rising Height and the Moisture Content Distribution in the Silty Soil[J].Subgrade Engineering,2015(5):81-83.