钙质结核含量对钙质结核土压缩性缩尺效应影响研究

Influences of calcareous nodule content on scale effects of compressibility of cohesive soil containing calcareous nodules

钙质结核土的大尺寸试样和缩尺试样在压缩性等物理力学性质上存在缩尺效应,其主要受土体中钙质结核含量和级配组成的影响。然而,现有研究关注更多的是土体的级配组成对缩尺效应的影响,而忽略了钙质结核含量的影响效果。为此探讨了钙质结核含量对钙质结核土压缩性缩尺效应的影响行为,并揭示了其作用机理。研究结果表明:土体压缩性缩尺效应与钙质结核含量之间呈现阶梯曲线的关系,主要归因于在相同的钙质结核含量下,缩尺试样中的钙质结核更容易形成骨架效应。基于此,提出了一种考虑钙质结核骨架效应的土样屈服应力和压缩指数的计算模型,以减少试样的缩尺效应的影响。该计算模型可为利用缩尺试样压缩试验结果来获得大尺寸样压缩性参数提供新途径,经验证,计算结果可靠。

The samples of cohesive soil containing calcareous nodules(CSCN)with large and corresponding scale sizes have scale effects on the physical and mechanical properties such as compressibility,which are mainly affected by the calcareous nodule content(CNC)and the gradation composition.However,the current researches pay more attention to the influences of the gradation composition on the scale effects,while ignoring those of the CNC.The influences of the CNC on the scale effects of compressibility of the CSCN are discussed,and the relevant mechanism is revealed.The results show that the correlation between the scale effects of compressibility and the CNC is a step curve,which is mainly due to the fact that the calcareous nodules in the samples with the scale size are easier to form the skeleton effects under the same CNC.Based on this,considering the skeleton effects of calcareous nodules,a model for calculating the yield stress and compression index of samples is proposed to reduce the scale effects of samples.The proposed model may provide a new approach to obtain the compressibility parameters of samples with a large size by using the compression test results of samples with the corresponding scale size,which is reliable.