结构性软黏土损伤变量与扰动度的相关性研究

取样与施工过程会对天然沉积结构性软黏土产生扰动,使土体的工程性质发生演化,一些学者分别以扰动度和损伤变量两个特征参数对该问题进行了较为深入的研究,但扰动度与描述土体应力状态的损伤变量之间的相关性目前仍未明晰。为此,以连云港天然沉积结构性软黏土进行不同应力路径下快速加载试验模拟土体应力损伤,对损伤后土体进行固结试验和无侧限抗压强度试验,结合张孟喜提出的损伤变量以及两种常用的扰动度(变形和强度)的定义,评价了损伤后土体的损伤变量和扰动度,探讨二者间关系。结果表明,损伤后土体压缩曲线屈服前的斜率并未产生明显改变,即损伤变量与按变形定义的扰动度间关系不明显;而损伤变量与以强度定义的扰动度之间存在线性递增关系,说明了当土体沿着某一路径加载时,越接近破坏线,其损伤程度越高,土体的强度也随之降低。

A study of the correlation between the damage variable and disturbance degree of structural soft clay

Natural sedimentary clay can be disturbed in sampling and construction processes, resulting in the evolution of soil behavior. Although the disturbance degree and damage variable have been attracting many researchers’ attentions, but the relationship between them is still not clear. Here, the relationship between damage variable described by stress state and the disturbance degree represented by strength or deformation is discussed based on the experimental results. A marine clay, a typical quaternary sediments widely deposited in the Lianyungang coastal area, was selected and sampled with thin-walled tube method. The soil samples, trimmed into an appropriate size of 100 mm in length and 100 mm in diameter, were loaded quickly under different stress paths using GDS triaxial apparatus to simulate the damage process, and the consolidation and unconfined compression tests were conducted to investigate the disturbance degrees defined by the deformation and strength respectively. The relationships between damage variables controlled by the different stress paths and the disturbance degrees are developed. It is found that effect of the damage process on the compression curve is insignificant, and the unconfined compression strength decreases practically linearly with damage variables. These results imply that as stress path approaches to the failure line, the disturbance degree increases and the strength of soil decreases.