循环应力作用下饱和软粘土的不固结不排水强度与破坏准则

通过饱和软粘土循环三轴与循环扭剪试验，研究了循环应力作用下饱和软粘土不固结不排水强度的变化。结果表明，当循环破坏次数给定后，饱和软粘土的不固结不排水循环强度取决于试验土样受到的静剪（偏）应力，与其受到的围压力无关；当作用在试样上的静剪应力比（静偏应力比）从0.3变化至0.6时，饱和软粘土循环强度也逐渐增大；进一步依据Mises破坏准则，通过分析循环扭剪试验确定的循环剪切强度与循环三轴试验确定的循环压缩强度之间的关系，阐明了循环荷载作用下饱和软粘土不固结不排水强度满足Mises破坏准则。依据本文研究结论，可以通过特定试验建立描述一般应力状态饱和软粘土单元不固结不排水循环强度的变化关系。

Unconsolidated Undrained Strength and Failure Criterion of the Soft Clay under Cyclic Stresses

The unconsolidated undrained strength of the saturated soft clay was researched by cyclic torsion and cyclic triaxial tests under cyclic stresses. Research results showed following conclusions. The unconsolidated undrained cyclic strength depends on the static shear (deviatoric) stress acting on test specimens and is independent of the confining pressure acting on test specimens for a specified number of cycles to failure. When static shear stress ratio acting on specimens increases from 0.3 to 0.6, cyclic strength of the saturated soft clay also increases. The unconsolidated undrained cyclic strength satisfies Mises failure criterion by analyzing relation between the cyclic shear strength from cyclic torsion shear tests and the cyclic compressive strength from cyclic triaxial tests based Mises failure criterion. The relationship describing unconsolidated undrained cyclic strength of saturated soft clay elements with general stress states can be determined by specified tests based on conclusions in the paper.