吸力控制下非饱和粉土的动力变形特性

Dynamic deformation characteristics of unsaturated silt under suction control

利用美国GCTS公司生产的吸力可控USTX-2000全自动非饱和土/饱和土动三轴仪,在控制吸力条件下对非饱和粉土的动力变形特性进行试验研究.开展循环荷载下的动力变形试验,得到了非饱和粉土试样的动应力应变骨架曲线、动弹性模量和阻尼比.试验结果表明:在动荷载作用下,吸力控制下的非饱和粉土动应力应变关系骨架曲线呈双曲线形,且吸力越大,骨架曲线越高;非饱和粉土的动弹性模量随吸力的增大而增大,但没有净围压增大效果显著;非饱和粉土的阻尼比随吸力的增大而减小,但减小幅度没有净围压增大那样显著;非饱和粉土的动应力应变关系骨架曲线、动弹性模量以及阻尼比随吸力的变化规律可用非饱和土的平均骨架应力值的变化解释.

By using a suction-controllable dynamic triaxii testing system USTX-2000 for the unsaturated and saturated soils developed by GCTS Company, the dynamic de- formation characteristics of unsaturated silt have been studied with suctions being con- trolled. Test results of dynamic deformation characteristics are obtained including the skeleton curve of dynamic stress-strain relation, dynamic modulus, and damping ratio. The following results are obtained. Skeleton curves of unsaturated silt under suction control are hyperbolic under dynamic loading, and the larger the suction, the higher the skeleton curves. The dynamic modulus of unsaturated silt increases with the increasing suction, and the effect of suction on dynamic modulus is less than that of the confining pressure. The damping ratio of unsaturated silt decreases with the increasing suction, and the effect of suction on the damping ratio is less than that of the confining pressure. Changes in the skeleton curves of dynamic stress-strain relation, dynamic modulus and damping ratio with the suction can be explained by the change in the average skeleton stress.