循环荷载下偏压固结饱和粉土刚度软化规律研究

Research on Stiffness Softening Rules of Saturated Anisotropic Consolidated Silty Soil under Cyclic Loading

以研究饱和粉土在循环荷载下长期变形和刚度软化为目的,通过GDS动三轴试验仪开展了一系列不同动应力比和不同固结应力影响下的偏压固结试验,分析了饱和粉土的动应力~应变曲线的变化趋势,揭示了累积孔压、累积应变与循环次数的关系。试验结果表明:刚度软化、累积应变、累积孔压均与动应力比、固结应力、循环次数有关,随着循环次数、动应力比、固结应力的增加,刚度软化加剧,累积孔压、累积应变增大。建立了刚度软化模型,通过对试验数据进行拟合分析发现,软化系数与累积孔压、累积应变呈指数关系,且累积孔压的关系更加显著。该模型参数少,易获取,易嵌入本构模型中,应用方便。

In order to study the long-term deformation and stiffness softening of saturated silty soil under cyclic loading,a series of anisotropic consolidated silty soil tests under different dynamic stress ratios and different consolidation stresses are carried out by GDS dynamic triaxial apparatus.The trend of dynamic stress-strain curve of saturated silt is analyzed,and the relationship between cumulative pore pressure,cumulative strain and cycle number is revealed.The experimental results show that stiffness softening,cumulative strain and cumulative pore pressure are all related to dynamic stress ratio,consolidation stress and cycle number.With the increase of cycle number,when dynamic stress ratio and consolidation stress are higher,the stiffness softening of silt will be more dramatically,and the cumulative pore pressure as well as cumulative strain will increase faster.A stiffness softening model is established.Through fitting and analyzing the test data,it is found that the softening coefficient is exponentially related to cumulative pore pressure and cumulative strain,and the cumulative pore pressure is more significant.Having fewer parameters,this stiffness softening model for saturated silty soil is easy be embedded in the constitutive model,and easy to be applied.