摘要
研究土体压缩过程孔隙的分形特性时,常常对试验测量范围内所有孔隙进行整体分析。然而,研究发现大小孔隙分形行为存在较大差别,特别对压缩的响应也显著不同。为阐述黏性土压缩过程大小孔隙的不同响应及分形特征,并对其变化规律进行刻画,以不同干密度的武汉黏性土为研究对象,利用压汞法获取土体孔隙分布数据,基于分形理论拟合分析其分维数。研究发现:孔隙孔径-体积分布图中,均存在特殊的临界孔径现象,临界孔径前后的孔隙分布规律及其对压缩变形的响应显著不同,将大于临界孔径的孔隙定义为大孔隙,小于临界孔径的孔隙定义为小孔隙;小孔隙分布具有天然较强的分形特征,且基本不随干密度的变化而变化,称之为固有分形特征;大孔隙分布远离固有分形特征,分形行为较弱;随着干密度的不断增大,大孔隙的分形特征逐渐增强,且不断逼近小孔隙的固有分形特征。因此,小孔隙的固有分形特征可作为黏性土压缩的基准指标,压缩是迫使大孔隙不断调整趋于更强分形分布且逐步向基准指标靠拢的过程。
The holistic analysis of all the pores within the range of experimental measurements is often performed when studying the fractal characteristic of soil pores under compression. However, this studies show that the fractal behavior of large pores has great difference with that of small pores, especially their response to compression. To illuminate the different fractal characteristics, the different responses of large and small pores under compression, and describe their variation laws, the pore-size distribution data of Wuhan clay with different dry density are obtained by mercury intrusion method. Afterward, these pore-size distribution data are analyzed and fitted to obtain the fractal dimensions based on fractal theory. The result shows that, there is a special critical pore-size in the pore volume and pore-size distribution curve. The distribution laws of pores larger and smaller than critical pore-size, as well as their responses to compression deformation, are significant different. The pores larger than the critical pore-size are defined as large pores and those smaller than the critical pore-size are defined as small pores. The distribution of small pores has stronger natural fractal characteristic, and does not vary with the dry density, which is referred to as intrinsic fractal characteristic. The distribution of large pores is far from the intrinsic fractal characteristic, which indicates that its fractal behavior is weaker than that of small pores. With the increasing of dry density, the fractal characteristic of large pores is gradually enhanced to continually approach the intrinsic fractal characteristic of small pores. Therefore, the intrinsic fractal characteristic of small pores can be used as a compacted reference indicator of clay, and the essence of compression process is that the large pores adjust to a stronger fractal distribution under compression and gradually approach the reference indicator.
作者
陶高梁
朱学良
胡其志
庄心善
何俊
陈银
TAO Gao-liang;ZHU Xue-liang;HU Qi-zhi;ZHUANG Xin-shan;HE Jun;CHEN Yin(School of Civil Engineering,Architecture and Enviroment,Hubei University & Technology,Wuhan,Hubei 430068,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第1期81-90,共10页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.51409097
No.51408201
No.41772332)
湖北省自然科学基金项目(No.2015CFB297
No.2014CFB591)
湖北省教育厅科研计划项目(No.D20161405)~~
关键词
压汞法
分形理论
临界孔径
固有分形特征
mercury intrusion method
fractal theory
critical pore-size
intrinsic fractal characteristic
