不同应力分量耦合模式下天津滨海饱和黏性土变形特性研究

Deformation Behavior of Tianjin Binhai Saturated Clay under a Coupling Mode of Different Stress Components

摘要:

地基土单元体在地震荷载作用下将产生主应力轴连续旋转，不同的应力耦合模式对土的强度、孔压以及变形等特性影响显著。利用GCTS空心圆柱扭剪仪，对天津滨海软土场地饱和黏性土进行K₀固结下的不同应力耦合模式的循环剪切试验。着重对比相同应力路径下竖向和扭剪双向耦合加载模式，内外围压和扭剪的三向耦合加载模式以内外围压、竖向和扭剪的四向耦合加载模式条件下饱和黏性土的变形特性、循环软化特性。试验结果表明：在相同的动强度下，四向耦合应力模式更容易破坏且变形特性以及软化特性较双向、三向耦合下发展更加迅速；剪应力分量对试样软化变形特性的影响更加显著。

Abstract:

Continuous rotation of the principal stress axis of a foundation soil element will occur under the action of seismic load, and different stress coupling modes have shown significant effect on the strength, pore pressure, and deformation of soil. In this paper, the cyclic shear tests on saturated clay in Tianjin coastal site under K₀ consolidation and different stress coupling modes are carried out using the hollow cylinder torsional shear apparatus GCTS. Deformation behavior and cyclic softening characteristics of saturated clay under bi-directional, three-directional, and four-directional coupled loading modes with the same stress paths are compared. The experimental results showed that, under the same dynamic strength, saturated clay is more easily destroyed under a four-directional coupled stress mode, and the deformation and softening characteristics under this mode develop more rapidly than under bi-directional and three-directional coupled loading modes under the same dynamic strength. The effect of the shear stress component on the softening deformation characteristics of samples is more significant.