轴对称状态下土体剪切带触发形成的分叉理论

Bifurcation of soils at inception of shear band under axisymmetric conditions

室内试验观察到三轴压缩试样在特定的应力状态下有剪切带的出现,但这种轴对称状态的土体失稳现象从理论上一直没有得到严格的验证。鉴于此,本文基于分叉理论对土体轴对称试样失稳问题作了详细的理论解析,证明了剪切带触发形成的必要条件,然后对完全排水条件下密砂三轴压缩试样进行分析,通过与室内试验结果进行对比,验证了本文理论解析的合理性。

This paper presents an interpretation of the bifurcation criteria required for shear band inception in a soil mass subjected to bifurcated deformations in a triaxial compression state,and the results are obtained based on the theory of finite deformations. The criteria are applied to analyze a dense sand specimen in the drained state of triaxial compression. The calculated results in uniform deformation mode are also given. Numerical calculations exhibit a good overall agreement with experimental observations for the inception of the localization and the mechanical response before the onset of bifurcation. 