不同固结条件下改良弱膨胀土微观分析  

Microscopic analysis of improved weak expansive soil under different consolidation conditions

作　　者：王欢[1] 曹素娟 李宝宝 WANG Huan;CAO Sujuan;LI Baobao(School of Civil and Architectural Engineering,Henan University,Kaifeng 475004,Henan,China)

机构地区：[1]河南大学土木建筑学院,河南开封475004

出　　处：《建筑科学与工程学报》2023年第4期163-170,共8页Journal of Architecture and Civil Engineering

基　　金：河南省高等学校重点科研项目(18A580002);开封市科技发展计划项目(1801004);甘肃省交通运输厅科研项目(2013-07)。

摘　　要：为研究黄泛区粉土质砂改良新乡地区弱膨胀土的改良效果,利用固结试验以及环境扫描电子显微镜试验分析了膨胀土及粉土质砂改良膨胀土的固结压缩特性及微观结构特性,对不同固结压力下的膨胀土、改良膨胀土微观结构进行定性分析,通过IPP和MATLAB软件对土体孔隙分形变化特征做定量分析。结果表明:土体的压缩特性主要与土体内部颗粒间排列形式、紧密程度及孔隙的分布等有关,随着固结压力的逐级增大,两种土样的孔隙比、压缩系数均呈现逐渐减小的趋势,且同一固结压力下改良膨胀土的孔隙比小于膨胀土,压缩系数大于膨胀土,表明改良膨胀土的结构压缩性优于膨胀土;对不同试验条件下的微观结构进行对比分析发现,两种土样孔隙分布具有明显的分形特性,在一定范围内,随着固结压力的逐级增大,膨胀土、改良膨胀土的孔隙分形维数逐渐增大,且改良膨胀土的分形维数大于膨胀土,但变化范围小于膨胀土,说明改良膨胀土内部孔隙结构分布复杂、结构更稳定,黄泛区粉土质砂可以显著改善新乡地区弱膨胀土的固结压缩特性。In order to study the improvement effect of silty sand on weak expansive soil in Xinxiang area,the consolidation compression characteristics and microstructure characteristics of expansive soil and silty sand modified expansive soil were analyzed by consolidation test and environmental scanning electron microscope test.The microstructure of expansive soil and modified soil under different consolidation pressures was qualitatively analyzed.The fractal variation characteristics of soil pores were quantitatively analyzed by IPP and MATLAB software.The results show that the compression characteristics of soil are mainly related to the arrangement form,compactness and pore distribution of particles in the soil.With the gradual increase of consolidation pressure,the void ratio and compression coefficient of the two kinds of soil samples show a decreasing trend,and the void ratio of the improved expansive soil is less than that of the expansive soil under the same consolidation pressure,while the compression coefficient is greater than that of the expansive soil,which indicates that the structural compressibility of the improved expansive soil is better than that of the expansive soil.Through the comparative analysis of the microstructure under different test conditions,it is found that the pore distribution of two kinds of soil samples has obvious fractal characteristics.Within a certain range,with the gradual increase of consolidation pressure,the pore fractal dimension of expansive soil and improved expansive soil increases gradually,the fractal dimension of improved expansive soil is greater than that of expansive soil,but the variation range is less than that of expansive soil,which indicates that the pore structure distribution of improved expansive soil is complex and the structure is more stable.The silt sand in the Yellow River flooding area can significantly improve the consolidation and compression characteristics of weak expansive soil in Xinxiang area.

关 键 词：改良膨胀土 粉土质砂 微观特性 分形维数 

分 类 号：TU443[建筑科学—岩土工程]