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基于二阶功准则及变形分叉理论,建立了分散性失稳和应变局部化失稳的理论判别准则,对K0固结不排水加载条件下饱和砂土的失稳特性进行了理论研究。分析结果表明,三轴应力状态下,土体表现为分散性失稳模式,应变局部化则不会发生。在试样初始状态较密实的状态下,由于相变作用,土体能够保持稳定,直至达到塑性极限破坏。在平面应变状态下,分散性失稳和应变局部化均可能发生,且分散性失稳先于应变局部化失稳出现。非共轴塑性流动法则的引入对分散性失稳预测结果无影响,然而对应变局部化的预测结果影响较大,且只有在引入了非共轴流动法则的条件下,应变局部化的理论预测结果才能与试验结果一致。
Based on the second-order work principle and deformation bifurcation theory, the theoretical criteria for the dispersion instability and strain instability are established, and the instability characteristics of saturated sand under K0 consolidation and undrained loading conditions are theoretically studied. The analysis results show that under triaxial stress state, the soil behaves as a dispersion instability mode, and strain localization does not occur. In the initial state of the sample is more dense state, due to the phase change, soil can remain stable until the plastic limit damage. In the plane strain state, the dispersion instability and strain localization may occur, and the dispersion instability occurs earlier than the strain localization instability. The introduction of non-coaxial plastic flow law has no effect on the prediction of dispersive instability. However, the prediction of strain localization has a great effect. And only when the non-coaxial flow law is introduced, the theoretical prediction of strain localization The results can be consistent with the test results.