饱和粉土静态液化性能试验研究

EXPERIMENT ON STATIC LIQUEFACTION CHARACTERISTICS OF SATURATED SILT SOIL

通过固结不排水三轴压缩试验,分析了围压、固结比和干密度等因素对饱和粉土静态液化特性的影响。试验结果表明,在干密度较小时,饱和粉土的偏应力-应变曲线呈现明显的硬变软化型,随轴向应变增大超静孔隙水压力增加、有效应力减小而发生静态液化,当干密度达到1.58 g·cm-3时,饱和粉土的偏应力-应变曲线表现出硬变硬化现象,超静孔隙水压力为负值或接近0,饱和粉土不再发生静态液化,即饱和粉土存在静态液化的干密度临界值;其他条件不变,随着围压、固结比或干密度的增大,偏应力峰值和残余强度均增大,静态液化势降低;根据有效应力路径建立了流滑面以作为饱和粉土稳定区与非稳定区的分界面。

Through consolidated undrained triaxial compression test, the influence of confining pressure,consolidation ratio and dry density on the static liquefaction characteristics of saturated silt soil are analyzed. The test results show that when the dry density is lower,the deviatoric stress-strain curves of saturated silt soil exhibit obvious strain softening characteristics. With the increase of axial strain,the excess pore water pressure increases and the effective stress decreases,which results in static liquefaction. When the dry density reaches to 1. 58 g·cm-3,the deviatoric stress-strain curves of saturated silt soil exhibit strain hardening characteristics,and the excess pore water pressure is negative or close to zero. So there is a critical value of dry density of static liquefaction. As other conditions are constant,with the increase of confining pressure,consolidation ratio or dry density,the peak value of deviatoric stress and the residual strength increase and the static liquefaction potential decreases. According to the effective stress path,the flow liquefaction is established as the interface of the stable zone and the unstable zone of saturated silt soil.