摘要
为了探究以羟基铝改性膨胀土(CSS)替代天然非膨胀性黏土(CNS)作为膨胀土包边材料的可行性,开展基本物理力学、化学分析和微观结构试验。试验结果表明:羟基铝通过吸附、离子交换、絮凝团聚作用降低膨胀土的亲水性和分散性;改性后膨胀土的卷曲状薄片结构基本消失,颗粒之间相互团聚呈现粗糙化和致密化,宏观基本物理性质、力学强度以及膨胀性能得到明显改善,塑性指数下降了43.5%,渗透性提高了1~2个数量级,膨胀性降低了37.5%~50%左右。综合来看,CSS的整体性能与CNS基本相当,且CSS含有比CNS更高浓度的K^(+)、Na^(+)、Ca^(2+)等离子成分,具备作为膨胀土包边覆盖层的潜力。研究成果可为后期开展CSS覆盖层技术的应用研究提供参考。
[Objective]Cohesive non-swelling soil(CNS)covering technology,when applied to the in-situ treatment of expansive soil foundations and slopes,frequently necessitates the modification of the expansive soil with traditional additives like lime to prepare suitable CNS materials.Research on the treatment of expansive soil using hydroxy-aluminum remains limited,and its application as an in-situ CNS material has not yet been reported.This study aims to ascertain the viability of using chemically stabilized soil(CSS)with hydroxy-aluminum solution as a CNS cushion layer material through laboratory experiments.[Methods]A series of basic physical-mechanical,chemical,and microstructural tests were carried out.Changes in particle size distribution,Atterberg limits,and compaction indices of soils were analyzed to evaluate the modification effect of hydroxy-aluminum on expansive soil.Subsequently,the permeability,shear strength,and swelling characteristics of the expansive soil(ES),CSS,and CNS were investigated under varying degrees of compaction(85%,90%,95%,100%).Ion concentration analysis of soils and microstructural analyses(XRD,SEM)were also conducted to assess the overall performance of CSS and validate its potential as a CNS cushion layer material.[Results](1)Following the addition of the hydroxy-aluminum solution,flocculation and agglomeration occurred between the hydroxy-aluminum and the clay particles of expansive soil.This process resulted in a reduction in the dispersibility and hydrophilicity of expansive soil,leading to denser particle packing.Consequently,the particle size distribution of expansive soil shifted,with an increase in silt content from 31%to approximately 46%,and a decrease in clay content from 65%to 51%,indicating a trend toward silty soil.(2)Plasticity index exhibited a substantial decrease,with a 43.5%reduction from 38.06 to 21.49.This decline resulted in a transformation of the soil classification from high-liquid-limit clay(CH)to low-liquid-limit clay(CL).These changes demonstrated a marked improvement in the basic physical properties of expansive soil.(3)Under varying degrees of compaction,the CSS exhibited substantial improvements in permeability,shear strength,and swelling characteristics compared to expansive soil.The permeability coefficient increased from 10-8 to 10-9 cm/s to the order of 10^(-7)cm/s,reaching a level comparable to that observed in the CNS.The shear strength parameters were enhanced;notably,at high compaction degree(K=100%),the shear strength of CSS even exceeded that of CNS.The swelling potential of CSS was significantly reduced,with the development of swelling deformation following the same trend as CNS.The swelling percentage decreased from 16%-24%to 8%-15%,representing a reduction of 37.5%-50%,which was slightly higher than CNS but still within the range of non-swelling soil.[Conclusion]Overall,the comprehensive performance of CSS was found to be essentially equivalent to that of CNS.The modification of expansive soil by hydroxy-aluminum solution primarily involved physicochemical reactions,including adsorption,ion exchange,and flocculation-agglomeration.The concentrations of K^(+),Na^(+),Ca^(2+),and Mg^(2+)of CSS all showed a significant increase.The findings suggest that CSS has a better potential for the inhibition of the swelling behavior of expansive soil.The results demonstrate the feasibility of utilizing CSS as a CNS cushion layer material for expansive soil.
作者
佘剑波
李帅
汤友生
鲜少华
卢正
姚海林
周永伟
SHE Jian-bo;LI Shuai;TANG You-sheng;XIAN Shao-hua;LU Zheng;YAO Hai-lin;ZHOU Yong-wei(Hubei Institute of Urban Geological Engineering,Wuhan 430050,China;Hubei Dijian Construction Co.,Ltd.,Wuhan 430050,China;State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China;China United Engineering Corporation Limited,Hangzhou 310052,China;Wuhan Municipal EngineeringDesign&Research Institute Co.,Ltd,Wuhan 430023,China)
出处
《长江科学院院报》
北大核心
2025年第9期131-138,共8页
Journal of Changjiang River Scientific Research Institute
基金
湖北省自然科学基金项目(2025AFD459,2023AFD214)
岩土力学与工程安全全国重点实验室开放基金(SKLGGES-024033)。
关键词
膨胀土
羟基铝
化学改性膨胀土
非膨胀性黏土
包边覆盖技术
expansive soil
hydroxy-aluminum solution
chemically stabilized soil
cohesive non-swelling soil
cushion layer technology
