南京砂的稳态特征研究

以南京砂的固结不排水试验为基础，对其稳态特征进行了研究。结果表明：在低围压下稳态线的曲线表达更符合实际情况，松散南京砂在低围压下广义剪应力终值接近于 0 而表现出不稳定；稳态是土体固有属性，稳态内摩擦角不仅可以通过稳定状态下的关系得到，也可通过同一围压下不同密实度南京砂的有效应力路径末端拟合得到，本研究得到南京砂稳态内摩擦角为 35.2 °；峰值强度高估了流滑中土体的强度，土体实际发挥的是残余强度，研究中建立了南京砂峰值强度和残余强度的关系；脆性指数能较好地反映南京砂应变软化程度和流滑的可能性；孔隙比的微小变化可导致南京砂软化程度的较大变化。

Steady-state properties of Nanjing sand

The CU tests on the reconstituted samples of Nanjing sand are performed and the experimental results are analyzed based on the steady-state theory.The steady-state line under low confining pressure is a curve,which is suitable for the behaviors of loose Nanjing sand in tests.The ultimate deviatoric stress of loose Nanjing sand under lower confining pressure is close to 0 and the behaviors in tests are unsteady.The steady state is the inherent attribute of soils.The steady-state angle of internal friction,35.2°for Nanjing sand,is obtained not only by a fitting curve of,but also by the linear extremity of effective stress paths under different relative densities.The peak strength of sand is overvalued during the flow slide,and there is the residual strength.The relation between the peak strength and the residual strength is obtained.The strength reduction in the strain softening and flow slide of Nanjing sand is expressed in terms of a brittleness index.A smaller change can lead to the larger change of the strain softening of Nanjing sand to great extent.