高压实膨润土膨胀渗透各向异性研究  

Swelling and Permeability Anisotropy of Highly Compacted Bentonite

作　　者：曹帅 毛耀建 陈宝[1] CAO Shuai;MAO Yaojian;CHEN Bao(College of Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程学院,上海200092

出　　处：《路基工程》2023年第1期7-12,共6页Subgrade Engineering

基　　金：国家自然科学基金项目:在围岩裂缝与缓冲材料交界处地下水对膨润土的侵蚀作用研究(41372270);内蒙古自治区交通运输厅建设科技项目(NJ-2015-13)。

摘　　要：采用自主设计的膨胀渗透各向异性试验系统,对平行压实方向与垂直压实方向的高庙子膨润土试样开展膨胀力试验与饱和渗透试验,研究初始干密度对两个方向的膨胀、渗透各向异性影响规律,并从膨润土的膨胀机理和压实效应分析膨胀力各向异性机理。结果表明:平行压实方向与垂直压实方向膨胀力均随干密度增加而呈指数增长;单向压实的膨润土试样膨胀力具有各向异性特征,膨胀力在垂直压实方向始终小于平行压实方向,膨胀力各向异性系数随干密度增加而降低,且当干密度超过1.5 g/cm^(3)时,膨胀力各向异性系数降低明显;在垂直压实方向上膨润土渗透系数略高于平行压实方向,但两者差异不大,表明单向压实作用对膨润土渗透各向异性特征影响不明显。The swelling and saturated permeability tests of Gaomiaozi bentonite specimens were performed in both parallel and perpendicular compaction directions by using a self-designed anisotropic swelling pressure and permeability test system. The effects of the initial dry density on the anisotropic swelling behavior and hydraulic conductivity in both directions were studied, and the mechanism for swelling pressure anisotropy was analyzed from the perspective of expansion mechanism and compaction effect of bentonite. The results show that: the swelling pressure increases exponentially with the increase of dry density in both compaction directions, parallel and perpendicular. The swelling pressure of unidirectional compacted bentonite samples is anisotropic, and the swelling pressure in the perpendicular compaction direction is always smaller than that in the parallel compaction direction. The anisotropy coefficient of swelling pressure decreases with the increase of dry density, and when the dry density exceeds 1.5 g/cm^(3), the anisotropy coefficient decreases remarkably. The permeability coefficient of bentonite in the perpendicular compaction direction is slightly higher than that in the parallel compaction direction, but the difference is little, which indicates that unidirectional compaction has no remarkable effect on the permeability anisotropy of bentonite.

关 键 词：膨润土 压实效应 膨胀力 渗透系数 各向异性 

分 类 号：TU43[建筑科学—岩土工程]