循环荷载作用下软黏土不排水累积变形特性

Reliability analysis of high level backfill based on chaotic optimization

在原状样与重塑样循环三轴试验的基础上,研究了软黏土在无静偏应力和有静偏应力循环荷载作用下的不排水瞬态累积变形特性,提出了考虑循环应力、循环振次、超固结比及静偏应力影响因素的土体应变本构模型。结果表明:软黏土变形规律受固结应力水平和土结构破坏影响甚大,当固结压力大于土体结构屈服应力时,其变形规律将趋近于重塑样;在循环荷载作用下,土样变形存在转折点,标志着土结构的破坏,本构模型宜按试样破坏前、后分段描述。

A series of undrained cyclic triaxial tests were performed on soft clays including undisturbed and remolded samples. The transient cumulative strains under the cyclic loading with or without the initial static deviatoric stress were analyzed, and a constitutive strain model considering the cyclic stress, cycle number, OCR and initial static deviatoric stress was proposed. It was shown that the deformation of soft clay was seriously influenced by the confining pressure and the failure of soil structure. When the confining pressure was larger than the yielding pressure of the undisturbed clay, the deformation characteristics would be close to those of the remolded clay. For these two kinds of samples, there existed a turning point on strain curves under the cyclic loading, indicating failure of soil structure, and the deformation of soil before and after this structure failure should be described separately.