基于土电阻率的黄土高填方地基细观变形机制

MESOSCOPIC DEFORMATION MECHANISM OF LOESS HIGH-FILL FOUNDATION BASED ON SOIL ELECTRICAL RESISTIVITY

为揭示黄土高填方地基产生变形的细观机制,以吕梁机场试验段为背景,基于土电阻率原理,研发土电阻率–固结联合测定仪,通过原位监测、现场取样和大量室内试验得到不同初始饱和度的Q3黄土在恒定荷载下的电阻率动态变化规律,提出以最优含水率为界限的Q3黄土"电阻率–应变曲线"模型,得到Q3黄土在恒定荷载下的水分迁移规律和结构变化特征。研究结果表明:高填方顶面工后总变形包括两大部分,即地基土及填方表面以下一定深度内填筑体的排水固结变形和深部超固结土的蠕变变形;初步揭示土体产生变形的细观演化规律,同时也为黄土高填方土体的本构模型建立和数值分析中模型的合理选取提供科学依据。

In order to reveal the mesoscopic deformation mechanism of loess high-fill foundation of Luliang airport,the soil electrical resistivity-consolidation combination measuring instrument are developed based on the principle of soil electrical resistivity.The dynamic variation law of the electrical resistivity of Q3 loess are obtained through in-situ monitoring,field sampling and laboratory test under different initial saturations and constant load.The electrical resistivity-strain curve model of Q3 loess to the limits of optimum moisture content is proposed;and its moisture migration and structural changing characteristics under constant load are also obtained.The study results show that the post-construction deformation of the loess high-fill foundation top surface is composed of the consolidation deformation of initial foundation and the fill bellow the surface to a certain depth and the long-term creep deformation of deep overconsolidated soil.The mesoscopic deformation mechanism of soil is revealed initially;and the study provides scientific basis for the establishment of loess high-fill soil constitutive model and reasonable selection of the numerical analysis model.