部分排水条件下饱和砂土的力学特性研究

利用英国GDS公司的STDTTS标准应力路径三轴仪开展了饱和砂土的部分排水试验，从超静孔隙水压力、有效应力路径与渐近状态特性等方面研究了部分排水条件下饱和砂土的力学特性。将渐近状态方程与剪胀方程耦合，并引入描述排水程度的状态参量mtml_15-0208_bak/img_0.png10.015.0，提出了相变应力比方程，将方程引入到土的应力路径本构模型，建立了饱和砂土的渐近状态本构模型。通过部分排水条件下饱和砂土的三轴试验结果，验证了所建模型的合理性。研究结果表明：排水条件控制着土体剪胀特性的发挥程度，进而从两个方面影响土的力学特性，一是荷载条件，即影响土体的有效应力路径，以及加载模式；二是土性条件，即影响土的抗剪强度的发挥程度，形成渐近状态。

Mechanical properties of saturated sand under partial drainage

Partial drainage tests on saturated sand are carried out by means of STDTTS standard stress path triaxial apparatus made by GDS Corporation of UK. By considering the aspects of excess pore water pressure, effective stress paths and asymptotic states, the mechanical properties of saturated sand under partial drainage are studied. By coupling asymptotic equation with dilatancy equation and introducing a status parameter named after ξ that describes the degrees of partial drainage, an equation for phase change stress ratio is presented. By introducing it into the constitutive model for soils considering stress paths, a constitutive model for saturated sand considering asymptotic states is established. The rationality of the model established is verified by the triaxial test results of saturated sand under partial drainage. The results indicate that drainage conditions control the expressing degrees of dilatancy of soils, and then affect the mechanical properties of soils from two aspects. One is the loading conditions that influence the effective stress paths of soils and the patterns of loading. The other is soil property conditions that influence the expressing degrees of the shear strength of soils, which lead to asymptotic states.