岩土材料受力从弹性进入塑性，最终发展到破坏，材料的屈服与破坏不同，屈服表示材料从弹性进入塑性状态，破坏表示从塑性发展到工程失稳。对于理想弹塑性材料，应力表述的判据难以区分屈服与破坏，为此提出采用极限应变作为岩土材料的破坏判据。本文给出了岩土材料动力极限应变的求解模型与方法，并以动力极限应变作为破坏准则，它既可以表述动力作用下材料的点破坏或开裂破坏，当点破坏贯通形成破坏面时，还可以表述材料整体破坏。通过地震作用下动力边坡工程算例，得到边坡滑体起裂的位置、演化过程和起裂极限荷载；当边坡中极限应变区贯通时得到边坡整体破坏极限荷载，并与数值极限分析中（超载法、强度折减法）采用位移不收敛破坏准则的计算结果比较，基本一致，验证了极限应变法在动力分析中的可行性。
Abstract
When bearing external load, geotechnical material will turn from elastic state to plastic state, eventually to destruction state. There is something different between yield situation and failure situation for geotechnical material. The yield situation represents that materials turn elastic state into a plastic state. However, in failure situation, geotechnical materials would get instability. For ideal elastic-plastic materials, stress criterion is difficult to distinguish between the yield and failure, so the limit strain is proposed as a damage criterion for geotechnical material. The solution model and method for the dynamic limit strain are put forward, and the dynamic limit strain is used as a failure criterion, which could express integral damage or local failure of materials under dynamic action. When the local failure surface gets connected, overall destruction would appear. Based on a slope project under earthquake action, the position of initial crack and evolutionary process of the crack at the slope as well as the limit load were got. The limit load calculated by limit strain criterion was in accordance with the results computed by the numerical limit analysis with displacement unconverged criterion (overload method and strength reduction method ), which shows the feasibility of the limit strain criterion in the dynamic analysis.
关键词
屈服 /
破坏 /
极限应变 /
破坏判据 /
地震作用
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Key words
yield /
failure /
limit strain /
failure criterion /
earthquake action
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