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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.“,”Steady state strength is an important parameter in evaluating the stability of sand deposits against flow liquefaction. Most loose sands exhibit the quasi-steady state (QSS) behavior under undrained triaxial loading, in which no unique ultimate steady state is reached. Stress-controlled triaxial tests were carried out on Unimin sand to study the steady state strength in the QSS behavior. The test results indicate that there are usually four distinct deformation stages in undrained tests on loose sand: initial stage, collapse stage, critical stress stage and post failure stage.The strain rate approximately remains constant in each deformation stage. The steady state, in which pore pressure, deviator stress, effective stress and strain rate remain constant, occurs in the collapse stage. The conventional definition of the steady state of deformation is not completely valid for the QSS behavior, and a modified definition is suggested.