吸力历史对非饱和粉土动力变形特性的影响

Effect of suction history on dynamic deformation characteristics of unsaturated silt

以非饱和粉土为研究对象,利用吸力可控的动三轴仪对其进行动力变形试验,得到了在不同净围压和不同吸力路径下非饱和粉土试样的骨架曲线、动弹性模量和阻尼比,研究了先脱湿后吸湿的吸力历史对其动力变形特性的影响。结果表明,在同一净围压和吸力下,非饱和粉土试样经历过先脱湿后吸湿的骨架曲线和动弹性模量比仅经过脱湿的要高,而试样经历过先脱湿后吸湿的阻尼比比仅经过脱湿的要小;此外,随着非饱和粉土试样经历过最大吸力的增大,其骨架曲线和动弹性模量增大,而阻尼比减小。试验结果可用非饱和土的平均骨架应力和弯液面水的表面张力作用来解释,并用两项联合预测非饱和土试样的最大剪切模量。

Dynamic deformations of unsaturated silt have been tested using a suction controllable dynamic triaxial testing apparatus. The skeleton curve, dynamic elastic modulus, damping ratio were obtained at different net confining pressures and suction paths. The effect of drying and wetting cycle on dynamic deformation characteristics of unsaturated silt was studied. Test results show that at the same net confining pressure and suction, the skeleton curve and dynamic elastic modulus of silty specimens subjected to drying and then wetting are higher than that of the specimens subjected to drying path only. but the damping ratio of specimens under drying and then wetting is lower under drying path only. With increasing the maximum suction experienced, the skeleton curve and dynamic elastic modulus of unsaturated silt increase, and oppositely the damping ratio decreases. The test results can be explained by the average skeleton stress and the effect of surface tension of meniscus water, which are together used to predict the maximum shear modulus of unsaturated soil.