饱和砂土稳态性状的三轴试验研究

完全饱和松砂在不排水试验中达到液化后发生稳态变形,大多数松砂在三轴不排水试验中表现出准稳态性状,而不是达到唯一最终稳态.当前研究结果认为砂在稳态变形中的应力状态仅仅取决于孔隙比.本文通过一系列三轴不排水试验来测定饱和松砂、中密砂和密砂的稳态,一种先进的计算机控制三轴测试系统(MTS)应用于本项研究中.试验结果表明:准稳态不仅取决于孔隙比,还与围压有关.文中详细讨论了孔隙比和围压对准稳态的影响关系以及土样出现稳态和准稳态时的应变大小.另外,文中提出一个可供讨论的问题:一些密砂试验中常不出现临时稳态,其原因是试验中剪切应力带发生并扩展导致了土样局部颗粒破碎从而影响了试验结果.

Study of the Steady State Behavior for Saturated Sand in Triaxial Test

The steady state deformation occurs during undrained tests on fully saturated, loose sands after liquefaction has been achieved. Most loose sands exhibit the quasi steady state (QSS) behavior under undrained triaxial loading,in which no unique ultimate steady state is reached. The results of the present study indicate that the stress state of sand at a steady state deformation is determined by the void ratio alone. A series of experiments was carried out to measure the steady state for loose, medium dense and dense saturated sand in undrained triaxial tests. An advanced computer controlled triaxial testing system (MTS) was applied to this study. The test results show that the quasi steady state is governed by the confining stress and the void ratio. The relationship among these factors is discussed, as well as the strain quality while the steady state or quasi steady state occurs. For dense samples, no temporary steady state often appears in some tests, so a discussed problem is put forward that the reason is that the shear stress zone occurring and extending results in the soil particles breakage; thus it influences test results..