吹填人工岛地基钙质粉土夹层的渗透特性研究
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摘要
南海吹填钙质土地基中含有多层粒径小于0.075 mm的细颗粒钙质粉土夹层,这些粉土夹层的渗透性对人工岛地下淡水的形成具有重要影响。通过室内变水头试验研究了钙质粉土渗透系数与干密度、初始含水率之间的相关性,论证了Samarasinghe与Mesri公式在计算钙质粉土渗透系数上的可靠性;通过静态氮吸附试验对渗透试验前、后钙质粉土的孔径变化特征进行了分析。研究结果表明:钙质粉土的渗透系数在初始含水率相同时随着干密度的增大而减小,在干密度相同时随着初始含水率的增大而增大,且在饱和时渗透系数达到最大;Samarasinghe与Mesri公式对钙质粉土渗透系数的计算具有较高精度;钙质粉土为大孔材料,渗流作用下使更多的微孔和介孔转变为大孔,孔隙类型以一端开口的均匀圆筒形孔为主。研究成果可为南海的人工吹填岛地下水渗流场的计算分析提供科学依据。
The silty calcareous soil subgrade in the South China Sea contains fine particle calcareous silt interlayers with a particle size less than 0.075 mm. The permeability of these calcareous silt layers has an important effect on the development of underground fresh water in the islands. This study investigated correlations among the permeability coefficient, dry density and initial water content of calcareous silt through variable-head permeability tests in laboratory. The results demonstrate the reliability of Samarasinghe and Mesri formulas in calculating the permeability coefficient of calcareous silt. The variation of pore size of calcareous silty soil before and after infiltration test was analyzed by static nitrogen adsorption test. The results show that the permeability coefficient of calcareous silt decreases with the increase of the dry density, and increases with the increase of the initial water content. When the dry density is the same, and the permeability coefficient reaches the maximum at saturation. The Samarasinghe and Mesri formulae have high accuracy in calculating the permeability coefficient of calcareous silt. Seepage generates more micropores and transforms mesopores into macropores. The soil mainly shows pores with a uniform cylindrical hole with an opening at one end. This study provides a scientific reference for the calculation and analysis of groundwater seepage field in artificial reclamation island.
The silty calcareous soil subgrade in the South China Sea contains fine particle calcareous silt interlayers with a particle size less than 0.075 mm. The permeability of these calcareous silt layers has an important effect on the development of underground fresh water in the islands. This study investigated correlations among the permeability coefficient, dry density and initial water content of calcareous silt through variable-head permeability tests in laboratory. The results demonstrate the reliability of Samarasinghe and Mesri formulas in calculating the permeability coefficient of calcareous silt. The variation of pore size of calcareous silty soil before and after infiltration test was analyzed by static nitrogen adsorption test. The results show that the permeability coefficient of calcareous silt decreases with the increase of the dry density, and increases with the increase of the initial water content. When the dry density is the same, and the permeability coefficient reaches the maximum at saturation. The Samarasinghe and Mesri formulae have high accuracy in calculating the permeability coefficient of calcareous silt. Seepage generates more micropores and transforms mesopores into macropores. The soil mainly shows pores with a uniform cylindrical hole with an opening at one end. This study provides a scientific reference for the calculation and analysis of groundwater seepage field in artificial reclamation island.
引文
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[20]林海飞,程博,李树刚,等.新疆阜康矿区煤层孔隙结构特征的氮吸附实验研究[J].西安科技大学学报,2015,35(6):721-726.LIN Hai-fei,CHEN Bo,LI Shu-gang,et al.Nitrogen adsorption experimental study on pore structure characteristics of coal seams in Xinjiang Fukang mining area[J].Journal of Xi’an University of Science and Technology,2015,35(6):721-726.
[2]孙吉主,汪稔.钙质砂的颗粒破碎和剪胀特性的围压效应[J].岩石力学与工程学报,2004,23(4):641-644.SUN Ji-zhu,WANG Ren.Influence of confining pressure on particle breakage and shear expansion of calcareous sand[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(4):641-644.
[3]孙宗勋,黄鼎成.珊瑚礁工程地质研究进展[J].地球科学发展,1999,14(6):577-581.SUN Zong-xun,HUANG Ding-cheng.Research progresses on coral reef engineering geology[J].Advance in Earth Sciences,1999,14(6):577-581.
[4]钱琨,王新志,陈剑文,等.南海岛礁吹填钙质砂渗透特性试验研究[J].岩土力学,2017,38(6):1-8.QIAN Kun,WANG Xin-zhi,CHEN Jian-wen,et al.Experimental study on permeability of calcareous sand for islands in the South China Sea[J].Rock and Soil Mechanics,2017,38(6):1-8.
[5]莫洪韵.岛礁钙质砂、岩混合料工程力学性能研究.硕士学位论文[D].南京:东南大学,2015.MO Hong-yun.Research on the mechanics characteristics of calcareous sand-limestone mixture[D].Nanjing:School of Transportation of Southeast University,2015.
[6]叶正强,李爱群,杨国华.等.黏性土的渗透规律研究[J].东南大学学报,1999,29(5):121-125.YE Zheng-qiang,LI Ai-qun,YANG Guo-hua,et al.Study of permeability for cohesive soil[J].Journal of Southeast University,1999,29(5):121-125.
[7]陈勇,单红仙,贾永刚.黄河沉积粉土渗透系数变化研究[J].海洋湖沼通报,2005,(4):15-22.CHEN Yong,SHAN Hong-xian,JIA Yong-gang.A study on the variation in the seepage coefficient of yellow river silt[J].Transactions of Oceanology and Limnology,2005,(4):15-22.
[8]SAMARASINGHE A M,HUANG Y H.Permeability and consolidation of normally consolidated soils[J].Journal of the Geotechnical Engineering Division,ASCE,1982,108(NGT6):835-850.
[9]TAYLOR D W.Fundamentals of soil mechanics[M].New York:John Wiley&Sons.,1948.
[10]MESRI G,ROKHSAR A.Consolidation of normally consolidated clay[J].Journal of the Soil Mechanics and Foundations Division,ASCE,1974,100(GT8):889-903.
[11]MESRI G,OLSON R E.Mechanisms controlling the permeability of clays[J].Clay and Clay Mineral,1971.19(3):151-158.
[12]谢康和,郑辉,LEO C J.软黏土一维非线性大应变固结解析理论[J].岩土工程学报,2002,24(6):680-684.XIE Kang-he,ZHENG Hui,LEO C J.An analytical theory for one dimensional nonlinear large strain consolidation of soft clay[J].Chinese Journal of Geotechnical Engineering,2002,24(6):680-684.
[13]谢康和,齐添,胡安峰,等.基于GDS的黏土非线性渗透特性试验研究[J].岩土力学,2008,29(2):420-424.XIE Kang-he,QI Tian,HU An-feng,et al.Experimental study on nonlinear permeability characteristics of Xiaoshan clay[J].Rock and Soil Mechanics,2008,29(2):420-424.
[14]高凌霞,栾茂田,杨庆,等.饱和重塑黏土渗透性试验研究[J].岩土力学,2008,29(8):2267-2270.GAO Ling-xia,LUAN Mao-tian,YANG Qing,et al.Experimental study of permeability of unsaturated remoulded clays[J].Rock and Soil Mechanics,2008,29(8):2267-2270.
[15]刘维正,石名磊,缪林昌.天然沉积饱和黏土渗透系数试验研究与预测模型[J].岩土力学,2013,34(9):2501-2507.LIU Wei-zheng,SHI Ming-lei,MIAO Lin-chang.Experimental study of permeability coefficient of natural saturated clay and its prediction model[J].Rock and Soil Mechanics,2013,34(9):2501-2507.
[16]赵彦旭,张虎元,吕擎峰,等.压实黄土非饱和渗透系数试验研究[J].岩土力学,2010,31(6):1809-1812.ZHAO Yan-xu,ZHANG Hu-yuan,LU Qing-feng,et al.Experimental study of unsaturated permeability coefficient of compacted loess[J].Rock and Soil Mechanics,2010,31(6):1809-1812.
[17]南京水利科学研究院.SL237-1999土工试验规程[S].北京:中国水利水电出版社,1999.Nanjing Hydraulic Research Institute.SL 237-1999 Test methods of soils[S].Beijing:China Water&Power Press,1999.
[18]严继民,张启元.吸附与凝聚固体的表面与孔[M].北京:科学出版社,1979.YAN Ji-min,ZHANG Qi-yuan.Adsorption and coagulation-surface and pore of solid[M].Beijing:Science Press,1979.
[19]陈萍,唐修义.低温氮吸附法与煤中微孔隙特征的研究[J].煤炭学报,2001,26(5):552-556.CHEN Ping,TANG Xiu-yi.The research on the adsorption of nitrogen in low temperature and micro-pore properties in coal[J].Journal of China Coal Society,2001,26(5):552-556.
[20]林海飞,程博,李树刚,等.新疆阜康矿区煤层孔隙结构特征的氮吸附实验研究[J].西安科技大学学报,2015,35(6):721-726.LIN Hai-fei,CHEN Bo,LI Shu-gang,et al.Nitrogen adsorption experimental study on pore structure characteristics of coal seams in Xinjiang Fukang mining area[J].Journal of Xi’an University of Science and Technology,2015,35(6):721-726.