摘要
孔隙溶液浓度及组份改变会影响膨胀土颗粒间作用力,改变微观孔隙结构,从而影响土体的物理力学特性。为此,以宁明膨胀土为研究对象,采用不同浓度NaCl溶液制备泥浆预固结重塑样开展一维压缩试验和压汞试验,研究化学作用对重塑天然膨胀土的压缩性和微观孔隙结构的影响规律。结果表明:随着渗透吸力增加,颗粒间水化能力降低,物理化学力使土颗粒由分散状态转变为集聚体状态,形成了集聚体内孔和集聚体间孔,土体表现出双峰孔隙分布特征。预固结样(压力为20 kPa)的初始孔隙比随渗透吸力增加而减小,进而导致固结屈服应力增加;但是渗透吸力对压缩性影响不大,压缩指数和回弹指数基本不变。此外,利用固结系数计算了土体的渗透系数,随着竖向压力增加渗透系数降低;当竖向压力小于200 kPa时,随着渗透吸力增加,渗透系数先增加后减小,但是竖向压力超过200 kPa后,渗透系数变化不大。分析发现,渗透吸力增加导致大孔隙增加,渗透系数增加,但同时密实度增加会导致渗透系数降低,低竖向压力下渗透性受密实度和微观孔隙结构变化耦合作用控制。
Pore water chemistry will change the intergranular force and directly affect the microstructure, the physical mechanical properties are further affected for clays. To investigate the effect of pore solution on the compressive properties and microstructure of remolded nature clay, one-dimensional compression test and mercury intrusion porosimetry(MIP) were carried out on the Ningming expansive soil which saturated with the NaCl solutions. The results show that with the increase of osmotic suction, the particles change from uniform dispersion to flocculation structure and forming intra-aggregate pore and inter-aggregate pore. Thus, the salt content specimens exhibit a double pore-size distribution. The initial void ratio of pre-consolidated sample(20 kPa) decreased with the increase of osmotic suction, leading to the increase of consolidation yield stress. However, the osmotic suction had little effect on the compression and swelling index. The permeability decreased with the increase of vertical pressure. When the vertical pressure is lower than 200 kPa, the permeability increased first and then decreased with increasing osmotic suction, but as vertical pressure is greater than 200 kPa, the effect of osmotic suction on permeability was negligible. It is found that the permeability under low pressure is controlled by the coupling effect of microstructure and density. The increase of osmotic suction leads to the increase of macropore and permeability, while permeability is decreased with the increase of density.
作者
梁维云
韦昌富
颜荣涛
杨德欢
LIANG Wei-yun;WEI Chang-fu;YAN Rong-tao;YANG De-huan(Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering,Guilin University of Technology,Guilin,Guangxi 541004,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第12期4759-4766,共8页
Rock and Soil Mechanics
基金
国家自然科学基金（No.41572293,No.11562007,No.11372078)
广西自然科学基金（No.2017GXNSFAA198215）~~
关键词
膨胀土
NACL溶液
微观孔隙结构
一维压缩试验
expensive soil
NaCl solutions
microstructure
one-dimensional compression test
