压实黄土土水特征对其孔隙结构的响应  

Responding of soil-water characteristics of compacted loess soil to its pore structure

作　　者：王宇 李同录[1,2] 雷雨露[1,2] 李燕 WANG Yu;LI Tonglu;LEI Yulu;LI Yan(School of Geological Engineering and Geomatics,Chang'an University,Xi'an,Shaanxi 710061,China;Water Cycle and Geological Environment Observation and Research Station for the Chinese Loess Plateau,Zhengning,Gansu 745399,China)

机构地区：[1]长安大学地质工程与测绘学院,陕西西安710061 [2]黄土高原水循环与地质环境教育部野外科学观测研究站,甘肃正宁745399

出　　处：《岩石力学与工程学报》2022年第6期1246-1255,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41790442,41772278,42072311)。

摘　　要：干密度和制样含水率是影响压实黄土土水特征曲线的2个关键因素。研究旨在从微观角度揭示干密度和制样含水率对压实黄土宏观土水特性影响的机制,为此采集延安新城的填筑黄土,并用静压法制作为2组试样:A组制样含水率为10%,压实为1.40,1.60,1.80 g/cm^(3)三种不同干密度;B组制样含水率分别为10%,16%(最优含水率)、18%,压实到最大干密度1.79 g/cm^(3)。对2组试样分别使用接触式滤纸法测得了全范围的增湿土水特征曲线,使用注胶磨片法获得了扫描电镜平面图像,使用压汞法测得了孔隙分布曲线。试验结果表明,A组不同干密度压实土样的土水特征曲线在残余区基本重合,而在近饱和区和过渡区表现出规律性变化;B组不同制样含水率压实黄土制样的土水特征曲线也在残余区基本重合,且随着制样含水率增加,其空气阻塞值减小、过渡区吸力范围变宽,由单一增湿模式转变为双增湿模式。通过微结构分析发现,2组试样的土水特征本质上受孔隙分布的控制,土水特征曲线与孔隙分布曲线的重合点同拐点存在一一对应关系。中小孔隙的分布范围决定过渡区的吸力范围,优势孔隙大小决定过渡区的增湿速率,优势孔隙数或孔隙分布曲线峰值数(单峰或双峰)决定增湿模式(单一增湿或双增湿),重合的孔隙分布区曲线决定相似的土水特征曲线。Dry density and moulding water content are two key factors affecting the soil-water characteristic curve of compacted loess.This paper aims to study the influence of the dry density and the moulding water content on the macroscopic soil-water characteristics of compacted loess from microscopic perspective.For this purpose,the filled loess of Yan'an was collected,and two sets of samples were made by static pressure method.The moulding water content of group A with different dry densities of 1.40 g/cm^(3),1.60 g/cm^(3) and 1.80 g/cm^(3) is 10%,and the dry density of group B with different moulding water contents of 10%,16%(optimal water content)and 18%is the maximum(equal to 1.79 g/cm^(3)).In the study,the contact filter paper method was used to measure the full range of wetting soil-water characteristic curves,the SEM images were obtained using polished slices of epoxy-filling soil samples,and the pore distribution curves were measured by the mercury intrusion method.The test results show that the soil-water characteristic curves of the soil samples with different dry densities in group A basically overlap in the residual stage but present regular changes in the near saturated stage and the transition stage.The soil-water characteristic curves of group B also basically overlap in the residual stage,but that,with increasing the moulding water content,the air occlusion value decreases and the suction range of the transition zone widens,resulting in a change from a single wetting mode to a dual wetting mode in the transition stage.Through micro-structure analysis,it is found that the soil-water characteristics of the two sets of samples are essentially controlled by the pore size distribution and that there is a corresponding relationship between the coincident point and the intersection point of soil-water characteristic curves and pore distribution curves.The distribution range of the dominant pores determines the suction range of the transition stage,and the size of the dominant pores determines the wetting rate i

关 键 词：土力学 压实黄土 干密度 制样含水率 土水特征 孔隙分布 

分 类 号：TU44[建筑科学—岩土工程]