Post Peak Behavior of Granular Soils and its Effect on Un- drained Steady State Strength

土体峰后响应决定了土体在中高应变作用下的行为；这种情况发生在地震引起的流动破坏中，例如边坡不稳定或承载能力破坏。地震引起的水流破坏的例子有1971年圣费尔南多下游大坝的破坏，1965年和1985年智利尾矿坝的破坏，以及1964年日本新泻的承载能力破坏。本研究计划的目的是为土壤峰后响应的性质提供实验证据，并将这些结果转化为可管理的理论框架。不排水稳态强度作为土体稳态变形极限抗剪力的概念为评估液化和流滑潜力提供了一个框架。在用于确定这种关系的实验室测试中，必须发展均匀的应变；因此，在伺服控制、重型仪器控制的平面应变压缩和标准三轴装置上，对饱和砂土的剪切试样进行了变形均匀性的实验研究。

The post-peak response of soils governs the behavior of soil masses subjected to moderate to high levels of strain; this occurs during earthquake-induced flow failures, such as slope instabilities or bearing capacity failure. Examples of earthquake-induced flow failures are the failure of the Lower San Fernando dam in 1971, failure of tailings dams in Chile in 1965 and 1985, and the bearing capacity failures in Niigata, Japan, in 1964. The objective of this research program is to provide experimental evidence of the nature of the post-peak response of soils and to cast these results into a manageable theoretical framework. The concept of an undrained steady- state strength as a limiting shearing resistance for a soil undergoing steady-state deformations provides a framework for evaluating liquefaction and flow slide potential. It is imperative that uniform strains develop in laboratory tests used to define this relationship; thus the uniformity of deformation is being examined experimentally by shearing specimens of saturated sands in both servo-controlled, heavily-instrumented plane strain compression and a standard triaxial device.