库岸滑坡黏性土与河水物理化学作用试验研究

Physical and Chemical Reaction Between River Water and Clayey Soil from Reservoir Landslide

水库水位周期性升降加剧了河水与库岸滑坡堆积物松散土体之间的水土作用,对库岸表层岩土的工程性质会产生显著影响。从水土作用的角度研究河水对库岸黏性土工程性质的影响,通过X射线衍射试验、Zeta电位试验、可交换阳离子试验、固结快剪试验、电镜扫描试验等,对滑坡黏性土与河水作用前后的组分、微结构和抗剪强度进行了对比试验。结果表明:在黏性土与河水作用过程中,由于水化作用和离子吸附作用的共同影响,土颗粒表面Zeta电位降低;由于土颗粒对2价阳离子的吸附作用,结合水膜会变薄,重塑土的微结构和抗剪强度都有一定变化,河水处理后的黏性土在直剪试验中还因土颗粒结构的变化导致剪胀效应。由此揭示水土间物理化学作用在河水淹没范围内对细粒土工程性质影响的作用机理。

Water level fluctuation in reservoir intensifies the water-soil interaction between river water and loose soil of landslide deposit,and thereby profoundly affecting the engineering properties of surface rock-soil.The impact of river water on the engineering property of clayey soil at the reservoir bank is studied from the perspective of water-soil interaction.Contrast tests including X-ray diffraction,Zeta electric potential,exchangeable cation types,shear test for consolidated samples,and SEM are performed to study the change of components,microstructure and shear strength of clayey soil from landslide before and after the interaction.It is concluded that Zeta electric potential at the surface of soil particle decreases under the combined effect of hydration and cation absorption.The thickness of absorbed water of soil grains decreases,and the microstructure and shear strength of remoulded soil are somewhat varied as the cations absorb divalent cations to soil grains.Moreover,dilatancy effect is generated due to the change of soil particle structure in the shear test of water-treated clayey soil.The mechanism of water-soil interaction affecting on the engineering properties of fine-grained soil is finally revealed.