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残余强度或稳态强度的确定是砂土液化研究中的重要课题。饱和砂土有３种典型的不排水剪切特征：稳态性状、准稳态性状、和加工硬化性状。在三轴不排水剪切中，大部分松砂表现出准稳态性状。新近的研究表明，“准稳态性状”不是砂土的固有性状，而是三轴试验中的边界条件所导致。本文通过试验研究发现，饱和砂土在三轴不排水剪切中通常表现出４个明显不同的阶段：初始阶段、坍塌阶段、临界状态应力阶段、和后破坏阶段。稳态强度只有在坍塌阶段中才会较好地表现出来。文中还对变形稳态的定义作了修正和补充，并根据修正的变形稳态定义给出了Ｕｎｉｍｉｎ砂的稳态强度及其它的一些试验性质。
Determination of residual strength or steady-state strength is an important issue in the research of sand liquefaction. There are three typical undrained shear characteristics of saturated sand: steady state, quasi-steady state, and work hardening. In triaxial undrained shear, most of the loose sand exhibits quasi-steady state properties. Recent studies have shown that “quasi-steady-state traits” are not intrinsic properties of sand but rather due to boundary conditions in triaxial tests. Through the experimental study, we find that saturated sand generally shows four distinct stages in undrained triaxial shear: initial stage, collapse stage, critical stress stage and post-failure stage. Steady state strength will only be better demonstrated during the collapse phase. The definition of deformation steady state is also amended and supplemented. According to the modified steady state definition, the steady state strength of Unimin sand and some other experimental properties are given.