【摘要】 为模拟不同排水条件下不同干密度饱和黄土的加载工况,在200 kPa围压下,用GDS三轴仪对不同干密度饱和重塑黄土开展固结排水、部分排(吸)水、固结不排水三轴剪切试验,得到应力-应变关系、超静孔压变化和q-p’有效应力路径,揭示不同干密度饱和黄土试样在不同排水条件下的力学特性.结果表明,同一干密度下,排水条件改变了饱和黄土试样的剪胀、剪缩,进而影响强度的大小和发展方向,随着干密度增加,试样强度增大;超静孔压变化是试样剪胀、剪缩效应与排水条件耦合作用的结果,随着干密度增大,各排水条件下的超静孔压有不同程度的减小;排水条件对q-p’有效应力路径的方向有明显影响,随着干密度增大,各排水条件下的q-p’有效应力均增强.基于试验结果,建立了考虑干密度影响,用于描述饱和黄土试样力学特性的渐近状态方程和变相应力比方程,为进一步构建饱和重塑黄土渐进状态本构关系奠定基础.更多还原

【Abstract】 In order to simulate the loading conditions of saturated loess under different drainage conditions and dry densities, the triaxial shear tests of saturated remolded loess with different dry densities,including consolidation drainage, partial drainage(absorption) and consolidation undrainage, were carried out by GDS stress-strain triaxial apparatus at 200 kPa confining pressure. The mechanical properties of saturated remolded loess samples with different dry densities under different drainage conditions were revealed by the test results of the stress-strain relationship, the variation of excess pore pressure and the q-p’ effective stress path. The results showed that, under the same dry density, the drainage conditions changed the dilatancy and contraction of the saturated loess samples, and then affected the development direction of the strength, and with the increase of dry density, the deviatoric stress became larger; the change of the excess pore pressure was the result of the coupling effect of dilatancy, shrinkage and drainage conditions, and when the dry density increased, the excess pore pressure decreased to different degrees under different drainage conditions. Drainage conditions had an obvious influence on the development direction of q-p’ effective stress path, and with the increase of dry density, the q-p’ effective stress path was enhanced under different drainage conditions. Based on the experimental results, the asymptotic equation of state and the variable stress ratio equation were established to describe the mechanical properties of saturated loess samples with a view to the effect of dry density, thus laying a foundation for the further construction of the asymptotic constitutive relationship of saturated remolded loess.更多还原